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src/HOL/List.thy

author | wenzelm |

Fri, 16 Apr 2010 21:28:09 +0200 | |

changeset 36176 | 3fe7e97ccca8 |

parent 36154 | 11c6106d7787 |

child 36199 | 4d220994f30b |

permissions | -rw-r--r-- |

replaced generic 'hide' command by more conventional 'hide_class', 'hide_type', 'hide_const', 'hide_fact' -- frees some popular keywords;

(* Title: HOL/List.thy Author: Tobias Nipkow *) header {* The datatype of finite lists *} theory List imports Plain Presburger Sledgehammer Recdef uses ("Tools/list_code.ML") begin datatype 'a list = Nil ("[]") | Cons 'a "'a list" (infixr "#" 65) syntax -- {* list Enumeration *} "_list" :: "args => 'a list" ("[(_)]") translations "[x, xs]" == "x#[xs]" "[x]" == "x#[]" subsection {* Basic list processing functions *} primrec hd :: "'a list \<Rightarrow> 'a" where "hd (x # xs) = x" primrec tl :: "'a list \<Rightarrow> 'a list" where "tl [] = []" | "tl (x # xs) = xs" primrec last :: "'a list \<Rightarrow> 'a" where "last (x # xs) = (if xs = [] then x else last xs)" primrec butlast :: "'a list \<Rightarrow> 'a list" where "butlast []= []" | "butlast (x # xs) = (if xs = [] then [] else x # butlast xs)" primrec set :: "'a list \<Rightarrow> 'a set" where "set [] = {}" | "set (x # xs) = insert x (set xs)" primrec map :: "('a \<Rightarrow> 'b) \<Rightarrow> 'a list \<Rightarrow> 'b list" where "map f [] = []" | "map f (x # xs) = f x # map f xs" primrec append :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" (infixr "@" 65) where append_Nil:"[] @ ys = ys" | append_Cons: "(x#xs) @ ys = x # xs @ ys" primrec rev :: "'a list \<Rightarrow> 'a list" where "rev [] = []" | "rev (x # xs) = rev xs @ [x]" primrec filter:: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a list" where "filter P [] = []" | "filter P (x # xs) = (if P x then x # filter P xs else filter P xs)" syntax -- {* Special syntax for filter *} "_filter" :: "[pttrn, 'a list, bool] => 'a list" ("(1[_<-_./ _])") translations "[x<-xs . P]"== "CONST filter (%x. P) xs" syntax (xsymbols) "_filter" :: "[pttrn, 'a list, bool] => 'a list"("(1[_\<leftarrow>_ ./ _])") syntax (HTML output) "_filter" :: "[pttrn, 'a list, bool] => 'a list"("(1[_\<leftarrow>_ ./ _])") primrec foldl :: "('b \<Rightarrow> 'a \<Rightarrow> 'b) \<Rightarrow> 'b \<Rightarrow> 'a list \<Rightarrow> 'b" where foldl_Nil: "foldl f a [] = a" | foldl_Cons: "foldl f a (x # xs) = foldl f (f a x) xs" primrec foldr :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'a list \<Rightarrow> 'b \<Rightarrow> 'b" where "foldr f [] a = a" | "foldr f (x # xs) a = f x (foldr f xs a)" primrec concat:: "'a list list \<Rightarrow> 'a list" where "concat [] = []" | "concat (x # xs) = x @ concat xs" primrec (in monoid_add) listsum :: "'a list \<Rightarrow> 'a" where "listsum [] = 0" | "listsum (x # xs) = x + listsum xs" primrec drop:: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where drop_Nil: "drop n [] = []" | drop_Cons: "drop n (x # xs) = (case n of 0 \<Rightarrow> x # xs | Suc m \<Rightarrow> drop m xs)" -- {*Warning: simpset does not contain this definition, but separate theorems for @{text "n = 0"} and @{text "n = Suc k"} *} primrec take:: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where take_Nil:"take n [] = []" | take_Cons: "take n (x # xs) = (case n of 0 \<Rightarrow> [] | Suc m \<Rightarrow> x # take m xs)" -- {*Warning: simpset does not contain this definition, but separate theorems for @{text "n = 0"} and @{text "n = Suc k"} *} primrec nth :: "'a list => nat => 'a" (infixl "!" 100) where nth_Cons: "(x # xs) ! n = (case n of 0 \<Rightarrow> x | Suc k \<Rightarrow> xs ! k)" -- {*Warning: simpset does not contain this definition, but separate theorems for @{text "n = 0"} and @{text "n = Suc k"} *} primrec list_update :: "'a list \<Rightarrow> nat \<Rightarrow> 'a \<Rightarrow> 'a list" where "list_update [] i v = []" | "list_update (x # xs) i v = (case i of 0 \<Rightarrow> v # xs | Suc j \<Rightarrow> x # list_update xs j v)" nonterminals lupdbinds lupdbind syntax "_lupdbind":: "['a, 'a] => lupdbind" ("(2_ :=/ _)") "" :: "lupdbind => lupdbinds" ("_") "_lupdbinds" :: "[lupdbind, lupdbinds] => lupdbinds" ("_,/ _") "_LUpdate" :: "['a, lupdbinds] => 'a" ("_/[(_)]" [900,0] 900) translations "_LUpdate xs (_lupdbinds b bs)" == "_LUpdate (_LUpdate xs b) bs" "xs[i:=x]" == "CONST list_update xs i x" primrec takeWhile :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a list" where "takeWhile P [] = []" | "takeWhile P (x # xs) = (if P x then x # takeWhile P xs else [])" primrec dropWhile :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a list" where "dropWhile P [] = []" | "dropWhile P (x # xs) = (if P x then dropWhile P xs else x # xs)" primrec zip :: "'a list \<Rightarrow> 'b list \<Rightarrow> ('a \<times> 'b) list" where "zip xs [] = []" | zip_Cons: "zip xs (y # ys) = (case xs of [] => [] | z # zs => (z, y) # zip zs ys)" -- {*Warning: simpset does not contain this definition, but separate theorems for @{text "xs = []"} and @{text "xs = z # zs"} *} primrec upt :: "nat \<Rightarrow> nat \<Rightarrow> nat list" ("(1[_..</_'])") where upt_0: "[i..<0] = []" | upt_Suc: "[i..<(Suc j)] = (if i <= j then [i..<j] @ [j] else [])" primrec distinct :: "'a list \<Rightarrow> bool" where "distinct [] \<longleftrightarrow> True" | "distinct (x # xs) \<longleftrightarrow> x \<notin> set xs \<and> distinct xs" primrec remdups :: "'a list \<Rightarrow> 'a list" where "remdups [] = []" | "remdups (x # xs) = (if x \<in> set xs then remdups xs else x # remdups xs)" definition insert :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where "insert x xs = (if x \<in> set xs then xs else x # xs)" hide_const (open) insert hide_fact (open) insert_def primrec remove1 :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where "remove1 x [] = []" | "remove1 x (y # xs) = (if x = y then xs else y # remove1 x xs)" primrec removeAll :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where "removeAll x [] = []" | "removeAll x (y # xs) = (if x = y then removeAll x xs else y # removeAll x xs)" primrec replicate :: "nat \<Rightarrow> 'a \<Rightarrow> 'a list" where replicate_0: "replicate 0 x = []" | replicate_Suc: "replicate (Suc n) x = x # replicate n x" text {* Function @{text size} is overloaded for all datatypes. Users may refer to the list version as @{text length}. *} abbreviation length :: "'a list \<Rightarrow> nat" where "length \<equiv> size" definition rotate1 :: "'a list \<Rightarrow> 'a list" where "rotate1 xs = (case xs of [] \<Rightarrow> [] | x#xs \<Rightarrow> xs @ [x])" definition rotate :: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where "rotate n = rotate1 ^^ n" definition list_all2 :: "('a => 'b => bool) => 'a list => 'b list => bool" where [code del]: "list_all2 P xs ys = (length xs = length ys \<and> (\<forall>(x, y) \<in> set (zip xs ys). P x y))" definition sublist :: "'a list => nat set => 'a list" where "sublist xs A = map fst (filter (\<lambda>p. snd p \<in> A) (zip xs [0..<size xs]))" primrec splice :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" where "splice [] ys = ys" | "splice (x # xs) ys = (if ys = [] then x # xs else x # hd ys # splice xs (tl ys))" -- {*Warning: simpset does not contain the second eqn but a derived one. *} text{* \begin{figure}[htbp] \fbox{ \begin{tabular}{l} @{lemma "[a,b]@[c,d] = [a,b,c,d]" by simp}\\ @{lemma "length [a,b,c] = 3" by simp}\\ @{lemma "set [a,b,c] = {a,b,c}" by simp}\\ @{lemma "map f [a,b,c] = [f a, f b, f c]" by simp}\\ @{lemma "rev [a,b,c] = [c,b,a]" by simp}\\ @{lemma "hd [a,b,c,d] = a" by simp}\\ @{lemma "tl [a,b,c,d] = [b,c,d]" by simp}\\ @{lemma "last [a,b,c,d] = d" by simp}\\ @{lemma "butlast [a,b,c,d] = [a,b,c]" by simp}\\ @{lemma[source] "filter (\<lambda>n::nat. n<2) [0,2,1] = [0,1]" by simp}\\ @{lemma "concat [[a,b],[c,d,e],[],[f]] = [a,b,c,d,e,f]" by simp}\\ @{lemma "foldl f x [a,b,c] = f (f (f x a) b) c" by simp}\\ @{lemma "foldr f [a,b,c] x = f a (f b (f c x))" by simp}\\ @{lemma "zip [a,b,c] [x,y,z] = [(a,x),(b,y),(c,z)]" by simp}\\ @{lemma "zip [a,b] [x,y,z] = [(a,x),(b,y)]" by simp}\\ @{lemma "splice [a,b,c] [x,y,z] = [a,x,b,y,c,z]" by simp}\\ @{lemma "splice [a,b,c,d] [x,y] = [a,x,b,y,c,d]" by simp}\\ @{lemma "take 2 [a,b,c,d] = [a,b]" by simp}\\ @{lemma "take 6 [a,b,c,d] = [a,b,c,d]" by simp}\\ @{lemma "drop 2 [a,b,c,d] = [c,d]" by simp}\\ @{lemma "drop 6 [a,b,c,d] = []" by simp}\\ @{lemma "takeWhile (%n::nat. n<3) [1,2,3,0] = [1,2]" by simp}\\ @{lemma "dropWhile (%n::nat. n<3) [1,2,3,0] = [3,0]" by simp}\\ @{lemma "distinct [2,0,1::nat]" by simp}\\ @{lemma "remdups [2,0,2,1::nat,2] = [0,1,2]" by simp}\\ @{lemma "List.insert 2 [0::nat,1,2] = [0,1,2]" by (simp add: List.insert_def)}\\ @{lemma "List.insert 3 [0::nat,1,2] = [3,0,1,2]" by (simp add: List.insert_def)}\\ @{lemma "remove1 2 [2,0,2,1::nat,2] = [0,2,1,2]" by simp}\\ @{lemma "removeAll 2 [2,0,2,1::nat,2] = [0,1]" by simp}\\ @{lemma "nth [a,b,c,d] 2 = c" by simp}\\ @{lemma "[a,b,c,d][2 := x] = [a,b,x,d]" by simp}\\ @{lemma "sublist [a,b,c,d,e] {0,2,3} = [a,c,d]" by (simp add:sublist_def)}\\ @{lemma "rotate1 [a,b,c,d] = [b,c,d,a]" by (simp add:rotate1_def)}\\ @{lemma "rotate 3 [a,b,c,d] = [d,a,b,c]" by (simp add:rotate1_def rotate_def nat_number')}\\ @{lemma "replicate 4 a = [a,a,a,a]" by (simp add:nat_number')}\\ @{lemma "[2..<5] = [2,3,4]" by (simp add:nat_number')}\\ @{lemma "listsum [1,2,3::nat] = 6" by simp} \end{tabular}} \caption{Characteristic examples} \label{fig:Characteristic} \end{figure} Figure~\ref{fig:Characteristic} shows characteristic examples that should give an intuitive understanding of the above functions. *} text{* The following simple sort functions are intended for proofs, not for efficient implementations. *} context linorder begin fun sorted :: "'a list \<Rightarrow> bool" where "sorted [] \<longleftrightarrow> True" | "sorted [x] \<longleftrightarrow> True" | "sorted (x#y#zs) \<longleftrightarrow> x <= y \<and> sorted (y#zs)" primrec insort_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b \<Rightarrow> 'b list \<Rightarrow> 'b list" where "insort_key f x [] = [x]" | "insort_key f x (y#ys) = (if f x \<le> f y then (x#y#ys) else y#(insort_key f x ys))" definition sort_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b list \<Rightarrow> 'b list" where "sort_key f xs = foldr (insort_key f) xs []" abbreviation "sort \<equiv> sort_key (\<lambda>x. x)" abbreviation "insort \<equiv> insort_key (\<lambda>x. x)" definition insort_insert :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where "insort_insert x xs = (if x \<in> set xs then xs else insort x xs)" end subsubsection {* List comprehension *} text{* Input syntax for Haskell-like list comprehension notation. Typical example: @{text"[(x,y). x \<leftarrow> xs, y \<leftarrow> ys, x \<noteq> y]"}, the list of all pairs of distinct elements from @{text xs} and @{text ys}. The syntax is as in Haskell, except that @{text"|"} becomes a dot (like in Isabelle's set comprehension): @{text"[e. x \<leftarrow> xs, \<dots>]"} rather than \verb![e| x <- xs, ...]!. The qualifiers after the dot are \begin{description} \item[generators] @{text"p \<leftarrow> xs"}, where @{text p} is a pattern and @{text xs} an expression of list type, or \item[guards] @{text"b"}, where @{text b} is a boolean expression. %\item[local bindings] @ {text"let x = e"}. \end{description} Just like in Haskell, list comprehension is just a shorthand. To avoid misunderstandings, the translation into desugared form is not reversed upon output. Note that the translation of @{text"[e. x \<leftarrow> xs]"} is optmized to @{term"map (%x. e) xs"}. It is easy to write short list comprehensions which stand for complex expressions. During proofs, they may become unreadable (and mangled). In such cases it can be advisable to introduce separate definitions for the list comprehensions in question. *} (* Proper theorem proving support would be nice. For example, if @{text"set[f x y. x \<leftarrow> xs, y \<leftarrow> ys, P x y]"} produced something like @{term"{z. EX x: set xs. EX y:set ys. P x y \<and> z = f x y}"}. *) nonterminals lc_qual lc_quals syntax "_listcompr" :: "'a \<Rightarrow> lc_qual \<Rightarrow> lc_quals \<Rightarrow> 'a list" ("[_ . __") "_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ <- _") "_lc_test" :: "bool \<Rightarrow> lc_qual" ("_") (*"_lc_let" :: "letbinds => lc_qual" ("let _")*) "_lc_end" :: "lc_quals" ("]") "_lc_quals" :: "lc_qual \<Rightarrow> lc_quals \<Rightarrow> lc_quals" (", __") "_lc_abs" :: "'a => 'b list => 'b list" (* These are easier than ML code but cannot express the optimized translation of [e. p<-xs] translations "[e. p<-xs]" => "concat(map (_lc_abs p [e]) xs)" "_listcompr e (_lc_gen p xs) (_lc_quals Q Qs)" => "concat (map (_lc_abs p (_listcompr e Q Qs)) xs)" "[e. P]" => "if P then [e] else []" "_listcompr e (_lc_test P) (_lc_quals Q Qs)" => "if P then (_listcompr e Q Qs) else []" "_listcompr e (_lc_let b) (_lc_quals Q Qs)" => "_Let b (_listcompr e Q Qs)" *) syntax (xsymbols) "_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ \<leftarrow> _") syntax (HTML output) "_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ \<leftarrow> _") parse_translation (advanced) {* let val NilC = Syntax.const @{const_syntax Nil}; val ConsC = Syntax.const @{const_syntax Cons}; val mapC = Syntax.const @{const_syntax map}; val concatC = Syntax.const @{const_syntax concat}; val IfC = Syntax.const @{const_syntax If}; fun singl x = ConsC $ x $ NilC; fun pat_tr ctxt p e opti = (* %x. case x of p => e | _ => [] *) let val x = Free (Name.variant (fold Term.add_free_names [p, e] []) "x", dummyT); val e = if opti then singl e else e; val case1 = Syntax.const @{syntax_const "_case1"} $ p $ e; val case2 = Syntax.const @{syntax_const "_case1"} $ Syntax.const @{const_syntax dummy_pattern} $ NilC; val cs = Syntax.const @{syntax_const "_case2"} $ case1 $ case2; val ft = Datatype_Case.case_tr false Datatype.info_of_constr ctxt [x, cs]; in lambda x ft end; fun abs_tr ctxt (p as Free (s, T)) e opti = let val thy = ProofContext.theory_of ctxt; val s' = Sign.intern_const thy s; in if Sign.declared_const thy s' then (pat_tr ctxt p e opti, false) else (lambda p e, true) end | abs_tr ctxt p e opti = (pat_tr ctxt p e opti, false); fun lc_tr ctxt [e, Const (@{syntax_const "_lc_test"}, _) $ b, qs] = let val res = (case qs of Const (@{syntax_const "_lc_end"}, _) => singl e | Const (@{syntax_const "_lc_quals"}, _) $ q $ qs => lc_tr ctxt [e, q, qs]); in IfC $ b $ res $ NilC end | lc_tr ctxt [e, Const (@{syntax_const "_lc_gen"}, _) $ p $ es, Const(@{syntax_const "_lc_end"}, _)] = (case abs_tr ctxt p e true of (f, true) => mapC $ f $ es | (f, false) => concatC $ (mapC $ f $ es)) | lc_tr ctxt [e, Const (@{syntax_const "_lc_gen"}, _) $ p $ es, Const (@{syntax_const "_lc_quals"}, _) $ q $ qs] = let val e' = lc_tr ctxt [e, q, qs]; in concatC $ (mapC $ (fst (abs_tr ctxt p e' false)) $ es) end; in [(@{syntax_const "_listcompr"}, lc_tr)] end *} term "[(x,y,z). b]" term "[(x,y,z). x\<leftarrow>xs]" term "[e x y. x\<leftarrow>xs, y\<leftarrow>ys]" term "[(x,y,z). x<a, x>b]" term "[(x,y,z). x\<leftarrow>xs, x>b]" term "[(x,y,z). x<a, x\<leftarrow>xs]" term "[(x,y). Cons True x \<leftarrow> xs]" term "[(x,y,z). Cons x [] \<leftarrow> xs]" term "[(x,y,z). x<a, x>b, x=d]" term "[(x,y,z). x<a, x>b, y\<leftarrow>ys]" term "[(x,y,z). x<a, x\<leftarrow>xs,y>b]" term "[(x,y,z). x<a, x\<leftarrow>xs, y\<leftarrow>ys]" term "[(x,y,z). x\<leftarrow>xs, x>b, y<a]" term "[(x,y,z). x\<leftarrow>xs, x>b, y\<leftarrow>ys]" term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,y>x]" term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,z\<leftarrow>zs]" (* term "[(x,y). x\<leftarrow>xs, let xx = x+x, y\<leftarrow>ys, y \<noteq> xx]" *) subsubsection {* @{const Nil} and @{const Cons} *} lemma not_Cons_self [simp]: "xs \<noteq> x # xs" by (induct xs) auto lemmas not_Cons_self2 [simp] = not_Cons_self [symmetric] lemma neq_Nil_conv: "(xs \<noteq> []) = (\<exists>y ys. xs = y # ys)" by (induct xs) auto lemma length_induct: "(\<And>xs. \<forall>ys. length ys < length xs \<longrightarrow> P ys \<Longrightarrow> P xs) \<Longrightarrow> P xs" by (rule measure_induct [of length]) iprover subsubsection {* @{const length} *} text {* Needs to come before @{text "@"} because of theorem @{text append_eq_append_conv}. *} lemma length_append [simp]: "length (xs @ ys) = length xs + length ys" by (induct xs) auto lemma length_map [simp]: "length (map f xs) = length xs" by (induct xs) auto lemma length_rev [simp]: "length (rev xs) = length xs" by (induct xs) auto lemma length_tl [simp]: "length (tl xs) = length xs - 1" by (cases xs) auto lemma length_0_conv [iff]: "(length xs = 0) = (xs = [])" by (induct xs) auto lemma length_greater_0_conv [iff]: "(0 < length xs) = (xs \<noteq> [])" by (induct xs) auto lemma length_pos_if_in_set: "x : set xs \<Longrightarrow> length xs > 0" by auto lemma length_Suc_conv: "(length xs = Suc n) = (\<exists>y ys. xs = y # ys \<and> length ys = n)" by (induct xs) auto lemma Suc_length_conv: "(Suc n = length xs) = (\<exists>y ys. xs = y # ys \<and> length ys = n)" apply (induct xs, simp, simp) apply blast done lemma impossible_Cons: "length xs <= length ys ==> xs = x # ys = False" by (induct xs) auto lemma list_induct2 [consumes 1, case_names Nil Cons]: "length xs = length ys \<Longrightarrow> P [] [] \<Longrightarrow> (\<And>x xs y ys. length xs = length ys \<Longrightarrow> P xs ys \<Longrightarrow> P (x#xs) (y#ys)) \<Longrightarrow> P xs ys" proof (induct xs arbitrary: ys) case Nil then show ?case by simp next case (Cons x xs ys) then show ?case by (cases ys) simp_all qed lemma list_induct3 [consumes 2, case_names Nil Cons]: "length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> P [] [] [] \<Longrightarrow> (\<And>x xs y ys z zs. length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> P xs ys zs \<Longrightarrow> P (x#xs) (y#ys) (z#zs)) \<Longrightarrow> P xs ys zs" proof (induct xs arbitrary: ys zs) case Nil then show ?case by simp next case (Cons x xs ys zs) then show ?case by (cases ys, simp_all) (cases zs, simp_all) qed lemma list_induct4 [consumes 3, case_names Nil Cons]: "length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> length zs = length ws \<Longrightarrow> P [] [] [] [] \<Longrightarrow> (\<And>x xs y ys z zs w ws. length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> length zs = length ws \<Longrightarrow> P xs ys zs ws \<Longrightarrow> P (x#xs) (y#ys) (z#zs) (w#ws)) \<Longrightarrow> P xs ys zs ws" proof (induct xs arbitrary: ys zs ws) case Nil then show ?case by simp next case (Cons x xs ys zs ws) then show ?case by ((cases ys, simp_all), (cases zs,simp_all)) (cases ws, simp_all) qed lemma list_induct2': "\<lbrakk> P [] []; \<And>x xs. P (x#xs) []; \<And>y ys. P [] (y#ys); \<And>x xs y ys. P xs ys \<Longrightarrow> P (x#xs) (y#ys) \<rbrakk> \<Longrightarrow> P xs ys" by (induct xs arbitrary: ys) (case_tac x, auto)+ lemma neq_if_length_neq: "length xs \<noteq> length ys \<Longrightarrow> (xs = ys) == False" by (rule Eq_FalseI) auto simproc_setup list_neq ("(xs::'a list) = ys") = {* (* Reduces xs=ys to False if xs and ys cannot be of the same length. This is the case if the atomic sublists of one are a submultiset of those of the other list and there are fewer Cons's in one than the other. *) let fun len (Const(@{const_name Nil},_)) acc = acc | len (Const(@{const_name Cons},_) $ _ $ xs) (ts,n) = len xs (ts,n+1) | len (Const(@{const_name append},_) $ xs $ ys) acc = len xs (len ys acc) | len (Const(@{const_name rev},_) $ xs) acc = len xs acc | len (Const(@{const_name map},_) $ _ $ xs) acc = len xs acc | len t (ts,n) = (t::ts,n); fun list_neq _ ss ct = let val (Const(_,eqT) $ lhs $ rhs) = Thm.term_of ct; val (ls,m) = len lhs ([],0) and (rs,n) = len rhs ([],0); fun prove_neq() = let val Type(_,listT::_) = eqT; val size = HOLogic.size_const listT; val eq_len = HOLogic.mk_eq (size $ lhs, size $ rhs); val neq_len = HOLogic.mk_Trueprop (HOLogic.Not $ eq_len); val thm = Goal.prove (Simplifier.the_context ss) [] [] neq_len (K (simp_tac (Simplifier.inherit_context ss @{simpset}) 1)); in SOME (thm RS @{thm neq_if_length_neq}) end in if m < n andalso submultiset (op aconv) (ls,rs) orelse n < m andalso submultiset (op aconv) (rs,ls) then prove_neq() else NONE end; in list_neq end; *} subsubsection {* @{text "@"} -- append *} lemma append_assoc [simp]: "(xs @ ys) @ zs = xs @ (ys @ zs)" by (induct xs) auto lemma append_Nil2 [simp]: "xs @ [] = xs" by (induct xs) auto lemma append_is_Nil_conv [iff]: "(xs @ ys = []) = (xs = [] \<and> ys = [])" by (induct xs) auto lemma Nil_is_append_conv [iff]: "([] = xs @ ys) = (xs = [] \<and> ys = [])" by (induct xs) auto lemma append_self_conv [iff]: "(xs @ ys = xs) = (ys = [])" by (induct xs) auto lemma self_append_conv [iff]: "(xs = xs @ ys) = (ys = [])" by (induct xs) auto lemma append_eq_append_conv [simp, no_atp]: "length xs = length ys \<or> length us = length vs ==> (xs@us = ys@vs) = (xs=ys \<and> us=vs)" apply (induct xs arbitrary: ys) apply (case_tac ys, simp, force) apply (case_tac ys, force, simp) done lemma append_eq_append_conv2: "(xs @ ys = zs @ ts) = (EX us. xs = zs @ us & us @ ys = ts | xs @ us = zs & ys = us@ ts)" apply (induct xs arbitrary: ys zs ts) apply fastsimp apply(case_tac zs) apply simp apply fastsimp done lemma same_append_eq [iff, induct_simp]: "(xs @ ys = xs @ zs) = (ys = zs)" by simp lemma append1_eq_conv [iff]: "(xs @ [x] = ys @ [y]) = (xs = ys \<and> x = y)" by simp lemma append_same_eq [iff, induct_simp]: "(ys @ xs = zs @ xs) = (ys = zs)" by simp lemma append_self_conv2 [iff]: "(xs @ ys = ys) = (xs = [])" using append_same_eq [of _ _ "[]"] by auto lemma self_append_conv2 [iff]: "(ys = xs @ ys) = (xs = [])" using append_same_eq [of "[]"] by auto lemma hd_Cons_tl [simp,no_atp]: "xs \<noteq> [] ==> hd xs # tl xs = xs" by (induct xs) auto lemma hd_append: "hd (xs @ ys) = (if xs = [] then hd ys else hd xs)" by (induct xs) auto lemma hd_append2 [simp]: "xs \<noteq> [] ==> hd (xs @ ys) = hd xs" by (simp add: hd_append split: list.split) lemma tl_append: "tl (xs @ ys) = (case xs of [] => tl ys | z#zs => zs @ ys)" by (simp split: list.split) lemma tl_append2 [simp]: "xs \<noteq> [] ==> tl (xs @ ys) = tl xs @ ys" by (simp add: tl_append split: list.split) lemma Cons_eq_append_conv: "x#xs = ys@zs = (ys = [] & x#xs = zs | (EX ys'. x#ys' = ys & xs = ys'@zs))" by(cases ys) auto lemma append_eq_Cons_conv: "(ys@zs = x#xs) = (ys = [] & zs = x#xs | (EX ys'. ys = x#ys' & ys'@zs = xs))" by(cases ys) auto text {* Trivial rules for solving @{text "@"}-equations automatically. *} lemma eq_Nil_appendI: "xs = ys ==> xs = [] @ ys" by simp lemma Cons_eq_appendI: "[| x # xs1 = ys; xs = xs1 @ zs |] ==> x # xs = ys @ zs" by (drule sym) simp lemma append_eq_appendI: "[| xs @ xs1 = zs; ys = xs1 @ us |] ==> xs @ ys = zs @ us" by (drule sym) simp text {* Simplification procedure for all list equalities. Currently only tries to rearrange @{text "@"} to see if - both lists end in a singleton list, - or both lists end in the same list. *} ML {* local fun last (cons as Const(@{const_name Cons},_) $ _ $ xs) = (case xs of Const(@{const_name Nil},_) => cons | _ => last xs) | last (Const(@{const_name append},_) $ _ $ ys) = last ys | last t = t; fun list1 (Const(@{const_name Cons},_) $ _ $ Const(@{const_name Nil},_)) = true | list1 _ = false; fun butlast ((cons as Const(@{const_name Cons},_) $ x) $ xs) = (case xs of Const(@{const_name Nil},_) => xs | _ => cons $ butlast xs) | butlast ((app as Const(@{const_name append},_) $ xs) $ ys) = app $ butlast ys | butlast xs = Const(@{const_name Nil},fastype_of xs); val rearr_ss = HOL_basic_ss addsimps [@{thm append_assoc}, @{thm append_Nil}, @{thm append_Cons}]; fun list_eq ss (F as (eq as Const(_,eqT)) $ lhs $ rhs) = let val lastl = last lhs and lastr = last rhs; fun rearr conv = let val lhs1 = butlast lhs and rhs1 = butlast rhs; val Type(_,listT::_) = eqT val appT = [listT,listT] ---> listT val app = Const(@{const_name append},appT) val F2 = eq $ (app$lhs1$lastl) $ (app$rhs1$lastr) val eq = HOLogic.mk_Trueprop (HOLogic.mk_eq (F,F2)); val thm = Goal.prove (Simplifier.the_context ss) [] [] eq (K (simp_tac (Simplifier.inherit_context ss rearr_ss) 1)); in SOME ((conv RS (thm RS trans)) RS eq_reflection) end; in if list1 lastl andalso list1 lastr then rearr @{thm append1_eq_conv} else if lastl aconv lastr then rearr @{thm append_same_eq} else NONE end; in val list_eq_simproc = Simplifier.simproc @{theory} "list_eq" ["(xs::'a list) = ys"] (K list_eq); end; Addsimprocs [list_eq_simproc]; *} subsubsection {* @{text map} *} lemma map_ext: "(!!x. x : set xs --> f x = g x) ==> map f xs = map g xs" by (induct xs) simp_all lemma map_ident [simp]: "map (\<lambda>x. x) = (\<lambda>xs. xs)" by (rule ext, induct_tac xs) auto lemma map_append [simp]: "map f (xs @ ys) = map f xs @ map f ys" by (induct xs) auto lemma map_map [simp]: "map f (map g xs) = map (f \<circ> g) xs" by (induct xs) auto lemma map_comp_map[simp]: "((map f) o (map g)) = map(f o g)" apply(rule ext) apply(simp) done lemma rev_map: "rev (map f xs) = map f (rev xs)" by (induct xs) auto lemma map_eq_conv[simp]: "(map f xs = map g xs) = (!x : set xs. f x = g x)" by (induct xs) auto lemma map_cong [fundef_cong, recdef_cong]: "xs = ys ==> (!!x. x : set ys ==> f x = g x) ==> map f xs = map g ys" -- {* a congruence rule for @{text map} *} by simp lemma map_is_Nil_conv [iff]: "(map f xs = []) = (xs = [])" by (cases xs) auto lemma Nil_is_map_conv [iff]: "([] = map f xs) = (xs = [])" by (cases xs) auto lemma map_eq_Cons_conv: "(map f xs = y#ys) = (\<exists>z zs. xs = z#zs \<and> f z = y \<and> map f zs = ys)" by (cases xs) auto lemma Cons_eq_map_conv: "(x#xs = map f ys) = (\<exists>z zs. ys = z#zs \<and> x = f z \<and> xs = map f zs)" by (cases ys) auto lemmas map_eq_Cons_D = map_eq_Cons_conv [THEN iffD1] lemmas Cons_eq_map_D = Cons_eq_map_conv [THEN iffD1] declare map_eq_Cons_D [dest!] Cons_eq_map_D [dest!] lemma ex_map_conv: "(EX xs. ys = map f xs) = (ALL y : set ys. EX x. y = f x)" by(induct ys, auto simp add: Cons_eq_map_conv) lemma map_eq_imp_length_eq: assumes "map f xs = map g ys" shows "length xs = length ys" using assms proof (induct ys arbitrary: xs) case Nil then show ?case by simp next case (Cons y ys) then obtain z zs where xs: "xs = z # zs" by auto from Cons xs have "map f zs = map g ys" by simp moreover with Cons have "length zs = length ys" by blast with xs show ?case by simp qed lemma map_inj_on: "[| map f xs = map f ys; inj_on f (set xs Un set ys) |] ==> xs = ys" apply(frule map_eq_imp_length_eq) apply(rotate_tac -1) apply(induct rule:list_induct2) apply simp apply(simp) apply (blast intro:sym) done lemma inj_on_map_eq_map: "inj_on f (set xs Un set ys) \<Longrightarrow> (map f xs = map f ys) = (xs = ys)" by(blast dest:map_inj_on) lemma map_injective: "map f xs = map f ys ==> inj f ==> xs = ys" by (induct ys arbitrary: xs) (auto dest!:injD) lemma inj_map_eq_map[simp]: "inj f \<Longrightarrow> (map f xs = map f ys) = (xs = ys)" by(blast dest:map_injective) lemma inj_mapI: "inj f ==> inj (map f)" by (iprover dest: map_injective injD intro: inj_onI) lemma inj_mapD: "inj (map f) ==> inj f" apply (unfold inj_on_def, clarify) apply (erule_tac x = "[x]" in ballE) apply (erule_tac x = "[y]" in ballE, simp, blast) apply blast done lemma inj_map[iff]: "inj (map f) = inj f" by (blast dest: inj_mapD intro: inj_mapI) lemma inj_on_mapI: "inj_on f (\<Union>(set ` A)) \<Longrightarrow> inj_on (map f) A" apply(rule inj_onI) apply(erule map_inj_on) apply(blast intro:inj_onI dest:inj_onD) done lemma map_idI: "(\<And>x. x \<in> set xs \<Longrightarrow> f x = x) \<Longrightarrow> map f xs = xs" by (induct xs, auto) lemma map_fun_upd [simp]: "y \<notin> set xs \<Longrightarrow> map (f(y:=v)) xs = map f xs" by (induct xs) auto lemma map_fst_zip[simp]: "length xs = length ys \<Longrightarrow> map fst (zip xs ys) = xs" by (induct rule:list_induct2, simp_all) lemma map_snd_zip[simp]: "length xs = length ys \<Longrightarrow> map snd (zip xs ys) = ys" by (induct rule:list_induct2, simp_all) subsubsection {* @{text rev} *} lemma rev_append [simp]: "rev (xs @ ys) = rev ys @ rev xs" by (induct xs) auto lemma rev_rev_ident [simp]: "rev (rev xs) = xs" by (induct xs) auto lemma rev_swap: "(rev xs = ys) = (xs = rev ys)" by auto lemma rev_is_Nil_conv [iff]: "(rev xs = []) = (xs = [])" by (induct xs) auto lemma Nil_is_rev_conv [iff]: "([] = rev xs) = (xs = [])" by (induct xs) auto lemma rev_singleton_conv [simp]: "(rev xs = [x]) = (xs = [x])" by (cases xs) auto lemma singleton_rev_conv [simp]: "([x] = rev xs) = (xs = [x])" by (cases xs) auto lemma rev_is_rev_conv [iff]: "(rev xs = rev ys) = (xs = ys)" apply (induct xs arbitrary: ys, force) apply (case_tac ys, simp, force) done lemma inj_on_rev[iff]: "inj_on rev A" by(simp add:inj_on_def) lemma rev_induct [case_names Nil snoc]: "[| P []; !!x xs. P xs ==> P (xs @ [x]) |] ==> P xs" apply(simplesubst rev_rev_ident[symmetric]) apply(rule_tac list = "rev xs" in list.induct, simp_all) done lemma rev_exhaust [case_names Nil snoc]: "(xs = [] ==> P) ==>(!!ys y. xs = ys @ [y] ==> P) ==> P" by (induct xs rule: rev_induct) auto lemmas rev_cases = rev_exhaust lemma rev_eq_Cons_iff[iff]: "(rev xs = y#ys) = (xs = rev ys @ [y])" by(rule rev_cases[of xs]) auto subsubsection {* @{text set} *} lemma finite_set [iff]: "finite (set xs)" by (induct xs) auto lemma set_append [simp]: "set (xs @ ys) = (set xs \<union> set ys)" by (induct xs) auto lemma hd_in_set[simp]: "xs \<noteq> [] \<Longrightarrow> hd xs : set xs" by(cases xs) auto lemma set_subset_Cons: "set xs \<subseteq> set (x # xs)" by auto lemma set_ConsD: "y \<in> set (x # xs) \<Longrightarrow> y=x \<or> y \<in> set xs" by auto lemma set_empty [iff]: "(set xs = {}) = (xs = [])" by (induct xs) auto lemma set_empty2[iff]: "({} = set xs) = (xs = [])" by(induct xs) auto lemma set_rev [simp]: "set (rev xs) = set xs" by (induct xs) auto lemma set_map [simp]: "set (map f xs) = f`(set xs)" by (induct xs) auto lemma set_filter [simp]: "set (filter P xs) = {x. x : set xs \<and> P x}" by (induct xs) auto lemma set_upt [simp]: "set[i..<j] = {i..<j}" by (induct j) (simp_all add: atLeastLessThanSuc) lemma split_list: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs" proof (induct xs) case Nil thus ?case by simp next case Cons thus ?case by (auto intro: Cons_eq_appendI) qed lemma in_set_conv_decomp: "x \<in> set xs \<longleftrightarrow> (\<exists>ys zs. xs = ys @ x # zs)" by (auto elim: split_list) lemma split_list_first: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys" proof (induct xs) case Nil thus ?case by simp next case (Cons a xs) show ?case proof cases assume "x = a" thus ?case using Cons by fastsimp next assume "x \<noteq> a" thus ?case using Cons by(fastsimp intro!: Cons_eq_appendI) qed qed lemma in_set_conv_decomp_first: "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys)" by (auto dest!: split_list_first) lemma split_list_last: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set zs" proof (induct xs rule:rev_induct) case Nil thus ?case by simp next case (snoc a xs) show ?case proof cases assume "x = a" thus ?case using snoc by simp (metis ex_in_conv set_empty2) next assume "x \<noteq> a" thus ?case using snoc by fastsimp qed qed lemma in_set_conv_decomp_last: "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set zs)" by (auto dest!: split_list_last) lemma split_list_prop: "\<exists>x \<in> set xs. P x \<Longrightarrow> \<exists>ys x zs. xs = ys @ x # zs & P x" proof (induct xs) case Nil thus ?case by simp next case Cons thus ?case by(simp add:Bex_def)(metis append_Cons append.simps(1)) qed lemma split_list_propE: assumes "\<exists>x \<in> set xs. P x" obtains ys x zs where "xs = ys @ x # zs" and "P x" using split_list_prop [OF assms] by blast lemma split_list_first_prop: "\<exists>x \<in> set xs. P x \<Longrightarrow> \<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>y \<in> set ys. \<not> P y)" proof (induct xs) case Nil thus ?case by simp next case (Cons x xs) show ?case proof cases assume "P x" thus ?thesis by simp (metis Un_upper1 contra_subsetD in_set_conv_decomp_first self_append_conv2 set_append) next assume "\<not> P x" hence "\<exists>x\<in>set xs. P x" using Cons(2) by simp thus ?thesis using `\<not> P x` Cons(1) by (metis append_Cons set_ConsD) qed qed lemma split_list_first_propE: assumes "\<exists>x \<in> set xs. P x" obtains ys x zs where "xs = ys @ x # zs" and "P x" and "\<forall>y \<in> set ys. \<not> P y" using split_list_first_prop [OF assms] by blast lemma split_list_first_prop_iff: "(\<exists>x \<in> set xs. P x) \<longleftrightarrow> (\<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>y \<in> set ys. \<not> P y))" by (rule, erule split_list_first_prop) auto lemma split_list_last_prop: "\<exists>x \<in> set xs. P x \<Longrightarrow> \<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>z \<in> set zs. \<not> P z)" proof(induct xs rule:rev_induct) case Nil thus ?case by simp next case (snoc x xs) show ?case proof cases assume "P x" thus ?thesis by (metis emptyE set_empty) next assume "\<not> P x" hence "\<exists>x\<in>set xs. P x" using snoc(2) by simp thus ?thesis using `\<not> P x` snoc(1) by fastsimp qed qed lemma split_list_last_propE: assumes "\<exists>x \<in> set xs. P x" obtains ys x zs where "xs = ys @ x # zs" and "P x" and "\<forall>z \<in> set zs. \<not> P z" using split_list_last_prop [OF assms] by blast lemma split_list_last_prop_iff: "(\<exists>x \<in> set xs. P x) \<longleftrightarrow> (\<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>z \<in> set zs. \<not> P z))" by (metis split_list_last_prop [where P=P] in_set_conv_decomp) lemma finite_list: "finite A ==> EX xs. set xs = A" by (erule finite_induct) (auto simp add: set.simps(2) [symmetric] simp del: set.simps(2)) lemma card_length: "card (set xs) \<le> length xs" by (induct xs) (auto simp add: card_insert_if) lemma set_minus_filter_out: "set xs - {y} = set (filter (\<lambda>x. \<not> (x = y)) xs)" by (induct xs) auto subsubsection {* @{text filter} *} lemma filter_append [simp]: "filter P (xs @ ys) = filter P xs @ filter P ys" by (induct xs) auto lemma rev_filter: "rev (filter P xs) = filter P (rev xs)" by (induct xs) simp_all lemma filter_filter [simp]: "filter P (filter Q xs) = filter (\<lambda>x. Q x \<and> P x) xs" by (induct xs) auto lemma length_filter_le [simp]: "length (filter P xs) \<le> length xs" by (induct xs) (auto simp add: le_SucI) lemma sum_length_filter_compl: "length(filter P xs) + length(filter (%x. ~P x) xs) = length xs" by(induct xs) simp_all lemma filter_True [simp]: "\<forall>x \<in> set xs. P x ==> filter P xs = xs" by (induct xs) auto lemma filter_False [simp]: "\<forall>x \<in> set xs. \<not> P x ==> filter P xs = []" by (induct xs) auto lemma filter_empty_conv: "(filter P xs = []) = (\<forall>x\<in>set xs. \<not> P x)" by (induct xs) simp_all lemma filter_id_conv: "(filter P xs = xs) = (\<forall>x\<in>set xs. P x)" apply (induct xs) apply auto apply(cut_tac P=P and xs=xs in length_filter_le) apply simp done lemma filter_map: "filter P (map f xs) = map f (filter (P o f) xs)" by (induct xs) simp_all lemma length_filter_map[simp]: "length (filter P (map f xs)) = length(filter (P o f) xs)" by (simp add:filter_map) lemma filter_is_subset [simp]: "set (filter P xs) \<le> set xs" by auto lemma length_filter_less: "\<lbrakk> x : set xs; ~ P x \<rbrakk> \<Longrightarrow> length(filter P xs) < length xs" proof (induct xs) case Nil thus ?case by simp next case (Cons x xs) thus ?case apply (auto split:split_if_asm) using length_filter_le[of P xs] apply arith done qed lemma length_filter_conv_card: "length(filter p xs) = card{i. i < length xs & p(xs!i)}" proof (induct xs) case Nil thus ?case by simp next case (Cons x xs) let ?S = "{i. i < length xs & p(xs!i)}" have fin: "finite ?S" by(fast intro: bounded_nat_set_is_finite) show ?case (is "?l = card ?S'") proof (cases) assume "p x" hence eq: "?S' = insert 0 (Suc ` ?S)" by(auto simp: image_def split:nat.split dest:gr0_implies_Suc) have "length (filter p (x # xs)) = Suc(card ?S)" using Cons `p x` by simp also have "\<dots> = Suc(card(Suc ` ?S))" using fin by (simp add: card_image inj_Suc) also have "\<dots> = card ?S'" using eq fin by (simp add:card_insert_if) (simp add:image_def) finally show ?thesis . next assume "\<not> p x" hence eq: "?S' = Suc ` ?S" by(auto simp add: image_def split:nat.split elim:lessE) have "length (filter p (x # xs)) = card ?S" using Cons `\<not> p x` by simp also have "\<dots> = card(Suc ` ?S)" using fin by (simp add: card_image inj_Suc) also have "\<dots> = card ?S'" using eq fin by (simp add:card_insert_if) finally show ?thesis . qed qed lemma Cons_eq_filterD: "x#xs = filter P ys \<Longrightarrow> \<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs" (is "_ \<Longrightarrow> \<exists>us vs. ?P ys us vs") proof(induct ys) case Nil thus ?case by simp next case (Cons y ys) show ?case (is "\<exists>x. ?Q x") proof cases assume Py: "P y" show ?thesis proof cases assume "x = y" with Py Cons.prems have "?Q []" by simp then show ?thesis .. next assume "x \<noteq> y" with Py Cons.prems show ?thesis by simp qed next assume "\<not> P y" with Cons obtain us vs where "?P (y#ys) (y#us) vs" by fastsimp then have "?Q (y#us)" by simp then show ?thesis .. qed qed lemma filter_eq_ConsD: "filter P ys = x#xs \<Longrightarrow> \<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs" by(rule Cons_eq_filterD) simp lemma filter_eq_Cons_iff: "(filter P ys = x#xs) = (\<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs)" by(auto dest:filter_eq_ConsD) lemma Cons_eq_filter_iff: "(x#xs = filter P ys) = (\<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs)" by(auto dest:Cons_eq_filterD) lemma filter_cong[fundef_cong, recdef_cong]: "xs = ys \<Longrightarrow> (\<And>x. x \<in> set ys \<Longrightarrow> P x = Q x) \<Longrightarrow> filter P xs = filter Q ys" apply simp apply(erule thin_rl) by (induct ys) simp_all subsubsection {* List partitioning *} primrec partition :: "('a \<Rightarrow> bool) \<Rightarrow>'a list \<Rightarrow> 'a list \<times> 'a list" where "partition P [] = ([], [])" | "partition P (x # xs) = (let (yes, no) = partition P xs in if P x then (x # yes, no) else (yes, x # no))" lemma partition_filter1: "fst (partition P xs) = filter P xs" by (induct xs) (auto simp add: Let_def split_def) lemma partition_filter2: "snd (partition P xs) = filter (Not o P) xs" by (induct xs) (auto simp add: Let_def split_def) lemma partition_P: assumes "partition P xs = (yes, no)" shows "(\<forall>p \<in> set yes. P p) \<and> (\<forall>p \<in> set no. \<not> P p)" proof - from assms have "yes = fst (partition P xs)" and "no = snd (partition P xs)" by simp_all then show ?thesis by (simp_all add: partition_filter1 partition_filter2) qed lemma partition_set: assumes "partition P xs = (yes, no)" shows "set yes \<union> set no = set xs" proof - from assms have "yes = fst (partition P xs)" and "no = snd (partition P xs)" by simp_all then show ?thesis by (auto simp add: partition_filter1 partition_filter2) qed lemma partition_filter_conv[simp]: "partition f xs = (filter f xs,filter (Not o f) xs)" unfolding partition_filter2[symmetric] unfolding partition_filter1[symmetric] by simp declare partition.simps[simp del] subsubsection {* @{text concat} *} lemma concat_append [simp]: "concat (xs @ ys) = concat xs @ concat ys" by (induct xs) auto lemma concat_eq_Nil_conv [simp]: "(concat xss = []) = (\<forall>xs \<in> set xss. xs = [])" by (induct xss) auto lemma Nil_eq_concat_conv [simp]: "([] = concat xss) = (\<forall>xs \<in> set xss. xs = [])" by (induct xss) auto lemma set_concat [simp]: "set (concat xs) = (UN x:set xs. set x)" by (induct xs) auto lemma concat_map_singleton[simp]: "concat(map (%x. [f x]) xs) = map f xs" by (induct xs) auto lemma map_concat: "map f (concat xs) = concat (map (map f) xs)" by (induct xs) auto lemma filter_concat: "filter p (concat xs) = concat (map (filter p) xs)" by (induct xs) auto lemma rev_concat: "rev (concat xs) = concat (map rev (rev xs))" by (induct xs) auto subsubsection {* @{text nth} *} lemma nth_Cons_0 [simp, code]: "(x # xs)!0 = x" by auto lemma nth_Cons_Suc [simp, code]: "(x # xs)!(Suc n) = xs!n" by auto declare nth.simps [simp del] lemma nth_append: "(xs @ ys)!n = (if n < length xs then xs!n else ys!(n - length xs))" apply (induct xs arbitrary: n, simp) apply (case_tac n, auto) done lemma nth_append_length [simp]: "(xs @ x # ys) ! length xs = x" by (induct xs) auto lemma nth_append_length_plus[simp]: "(xs @ ys) ! (length xs + n) = ys ! n" by (induct xs) auto lemma nth_map [simp]: "n < length xs ==> (map f xs)!n = f(xs!n)" apply (induct xs arbitrary: n, simp) apply (case_tac n, auto) done lemma hd_conv_nth: "xs \<noteq> [] \<Longrightarrow> hd xs = xs!0" by(cases xs) simp_all lemma list_eq_iff_nth_eq: "(xs = ys) = (length xs = length ys \<and> (ALL i<length xs. xs!i = ys!i))" apply(induct xs arbitrary: ys) apply force apply(case_tac ys) apply simp apply(simp add:nth_Cons split:nat.split)apply blast done lemma set_conv_nth: "set xs = {xs!i | i. i < length xs}" apply (induct xs, simp, simp) apply safe apply (metis nat_case_0 nth.simps zero_less_Suc) apply (metis less_Suc_eq_0_disj nth_Cons_Suc) apply (case_tac i, simp) apply (metis diff_Suc_Suc nat_case_Suc nth.simps zero_less_diff) done lemma in_set_conv_nth: "(x \<in> set xs) = (\<exists>i < length xs. xs!i = x)" by(auto simp:set_conv_nth) lemma list_ball_nth: "[| n < length xs; !x : set xs. P x|] ==> P(xs!n)" by (auto simp add: set_conv_nth) lemma nth_mem [simp]: "n < length xs ==> xs!n : set xs" by (auto simp add: set_conv_nth) lemma all_nth_imp_all_set: "[| !i < length xs. P(xs!i); x : set xs|] ==> P x" by (auto simp add: set_conv_nth) lemma all_set_conv_all_nth: "(\<forall>x \<in> set xs. P x) = (\<forall>i. i < length xs --> P (xs ! i))" by (auto simp add: set_conv_nth) lemma rev_nth: "n < size xs \<Longrightarrow> rev xs ! n = xs ! (length xs - Suc n)" proof (induct xs arbitrary: n) case Nil thus ?case by simp next case (Cons x xs) hence n: "n < Suc (length xs)" by simp moreover { assume "n < length xs" with n obtain n' where "length xs - n = Suc n'" by (cases "length xs - n", auto) moreover then have "length xs - Suc n = n'" by simp ultimately have "xs ! (length xs - Suc n) = (x # xs) ! (length xs - n)" by simp } ultimately show ?case by (clarsimp simp add: Cons nth_append) qed lemma Skolem_list_nth: "(ALL i<k. EX x. P i x) = (EX xs. size xs = k & (ALL i<k. P i (xs!i)))" (is "_ = (EX xs. ?P k xs)") proof(induct k) case 0 show ?case by simp next case (Suc k) show ?case (is "?L = ?R" is "_ = (EX xs. ?P' xs)") proof assume "?R" thus "?L" using Suc by auto next assume "?L" with Suc obtain x xs where "?P k xs & P k x" by (metis less_Suc_eq) hence "?P'(xs@[x])" by(simp add:nth_append less_Suc_eq) thus "?R" .. qed qed subsubsection {* @{text list_update} *} lemma length_list_update [simp]: "length(xs[i:=x]) = length xs" by (induct xs arbitrary: i) (auto split: nat.split) lemma nth_list_update: "i < length xs==> (xs[i:=x])!j = (if i = j then x else xs!j)" by (induct xs arbitrary: i j) (auto simp add: nth_Cons split: nat.split) lemma nth_list_update_eq [simp]: "i < length xs ==> (xs[i:=x])!i = x" by (simp add: nth_list_update) lemma nth_list_update_neq [simp]: "i \<noteq> j ==> xs[i:=x]!j = xs!j" by (induct xs arbitrary: i j) (auto simp add: nth_Cons split: nat.split) lemma list_update_id[simp]: "xs[i := xs!i] = xs" by (induct xs arbitrary: i) (simp_all split:nat.splits) lemma list_update_beyond[simp]: "length xs \<le> i \<Longrightarrow> xs[i:=x] = xs" apply (induct xs arbitrary: i) apply simp apply (case_tac i) apply simp_all done lemma list_update_nonempty[simp]: "xs[k:=x] = [] \<longleftrightarrow> xs=[]" by(metis length_0_conv length_list_update) lemma list_update_same_conv: "i < length xs ==> (xs[i := x] = xs) = (xs!i = x)" by (induct xs arbitrary: i) (auto split: nat.split) lemma list_update_append1: "i < size xs \<Longrightarrow> (xs @ ys)[i:=x] = xs[i:=x] @ ys" apply (induct xs arbitrary: i, simp) apply(simp split:nat.split) done lemma list_update_append: "(xs @ ys) [n:= x] = (if n < length xs then xs[n:= x] @ ys else xs @ (ys [n-length xs:= x]))" by (induct xs arbitrary: n) (auto split:nat.splits) lemma list_update_length [simp]: "(xs @ x # ys)[length xs := y] = (xs @ y # ys)" by (induct xs, auto) lemma map_update: "map f (xs[k:= y]) = (map f xs)[k := f y]" by(induct xs arbitrary: k)(auto split:nat.splits) lemma rev_update: "k < length xs \<Longrightarrow> rev (xs[k:= y]) = (rev xs)[length xs - k - 1 := y]" by (induct xs arbitrary: k) (auto simp: list_update_append split:nat.splits) lemma update_zip: "(zip xs ys)[i:=xy] = zip (xs[i:=fst xy]) (ys[i:=snd xy])" by (induct ys arbitrary: i xy xs) (auto, case_tac xs, auto split: nat.split) lemma set_update_subset_insert: "set(xs[i:=x]) <= insert x (set xs)" by (induct xs arbitrary: i) (auto split: nat.split) lemma set_update_subsetI: "[| set xs <= A; x:A |] ==> set(xs[i := x]) <= A" by (blast dest!: set_update_subset_insert [THEN subsetD]) lemma set_update_memI: "n < length xs \<Longrightarrow> x \<in> set (xs[n := x])" by (induct xs arbitrary: n) (auto split:nat.splits) lemma list_update_overwrite[simp]: "xs [i := x, i := y] = xs [i := y]" apply (induct xs arbitrary: i) apply simp apply (case_tac i, simp_all) done lemma list_update_swap: "i \<noteq> i' \<Longrightarrow> xs [i := x, i' := x'] = xs [i' := x', i := x]" apply (induct xs arbitrary: i i') apply simp apply (case_tac i, case_tac i') apply auto apply (case_tac i') apply auto done lemma list_update_code [code]: "[][i := y] = []" "(x # xs)[0 := y] = y # xs" "(x # xs)[Suc i := y] = x # xs[i := y]" by simp_all subsubsection {* @{text last} and @{text butlast} *} lemma last_snoc [simp]: "last (xs @ [x]) = x" by (induct xs) auto lemma butlast_snoc [simp]: "butlast (xs @ [x]) = xs" by (induct xs) auto lemma last_ConsL: "xs = [] \<Longrightarrow> last(x#xs) = x" by(simp add:last.simps) lemma last_ConsR: "xs \<noteq> [] \<Longrightarrow> last(x#xs) = last xs" by(simp add:last.simps) lemma last_append: "last(xs @ ys) = (if ys = [] then last xs else last ys)" by (induct xs) (auto) lemma last_appendL[simp]: "ys = [] \<Longrightarrow> last(xs @ ys) = last xs" by(simp add:last_append) lemma last_appendR[simp]: "ys \<noteq> [] \<Longrightarrow> last(xs @ ys) = last ys" by(simp add:last_append) lemma hd_rev: "xs \<noteq> [] \<Longrightarrow> hd(rev xs) = last xs" by(rule rev_exhaust[of xs]) simp_all lemma last_rev: "xs \<noteq> [] \<Longrightarrow> last(rev xs) = hd xs" by(cases xs) simp_all lemma last_in_set[simp]: "as \<noteq> [] \<Longrightarrow> last as \<in> set as" by (induct as) auto lemma length_butlast [simp]: "length (butlast xs) = length xs - 1" by (induct xs rule: rev_induct) auto lemma butlast_append: "butlast (xs @ ys) = (if ys = [] then butlast xs else xs @ butlast ys)" by (induct xs arbitrary: ys) auto lemma append_butlast_last_id [simp]: "xs \<noteq> [] ==> butlast xs @ [last xs] = xs" by (induct xs) auto lemma in_set_butlastD: "x : set (butlast xs) ==> x : set xs" by (induct xs) (auto split: split_if_asm) lemma in_set_butlast_appendI: "x : set (butlast xs) | x : set (butlast ys) ==> x : set (butlast (xs @ ys))" by (auto dest: in_set_butlastD simp add: butlast_append) lemma last_drop[simp]: "n < length xs \<Longrightarrow> last (drop n xs) = last xs" apply (induct xs arbitrary: n) apply simp apply (auto split:nat.split) done lemma last_conv_nth: "xs\<noteq>[] \<Longrightarrow> last xs = xs!(length xs - 1)" by(induct xs)(auto simp:neq_Nil_conv) lemma butlast_conv_take: "butlast xs = take (length xs - 1) xs" by (induct xs, simp, case_tac xs, simp_all) lemma last_list_update: "xs \<noteq> [] \<Longrightarrow> last(xs[k:=x]) = (if k = size xs - 1 then x else last xs)" by (auto simp: last_conv_nth) lemma butlast_list_update: "butlast(xs[k:=x]) = (if k = size xs - 1 then butlast xs else (butlast xs)[k:=x])" apply(cases xs rule:rev_cases) apply simp apply(simp add:list_update_append split:nat.splits) done subsubsection {* @{text take} and @{text drop} *} lemma take_0 [simp]: "take 0 xs = []" by (induct xs) auto lemma drop_0 [simp]: "drop 0 xs = xs" by (induct xs) auto lemma take_Suc_Cons [simp]: "take (Suc n) (x # xs) = x # take n xs" by simp lemma drop_Suc_Cons [simp]: "drop (Suc n) (x # xs) = drop n xs" by simp declare take_Cons [simp del] and drop_Cons [simp del] lemma take_1_Cons [simp]: "take 1 (x # xs) = [x]" unfolding One_nat_def by simp lemma drop_1_Cons [simp]: "drop 1 (x # xs) = xs" unfolding One_nat_def by simp lemma take_Suc: "xs ~= [] ==> take (Suc n) xs = hd xs # take n (tl xs)" by(clarsimp simp add:neq_Nil_conv) lemma drop_Suc: "drop (Suc n) xs = drop n (tl xs)" by(cases xs, simp_all) lemma take_tl: "take n (tl xs) = tl (take (Suc n) xs)" by (induct xs arbitrary: n) simp_all lemma drop_tl: "drop n (tl xs) = tl(drop n xs)" by(induct xs arbitrary: n, simp_all add:drop_Cons drop_Suc split:nat.split) lemma tl_take: "tl (take n xs) = take (n - 1) (tl xs)" by (cases n, simp, cases xs, auto) lemma tl_drop: "tl (drop n xs) = drop n (tl xs)" by (simp only: drop_tl) lemma nth_via_drop: "drop n xs = y#ys \<Longrightarrow> xs!n = y" apply (induct xs arbitrary: n, simp) apply(simp add:drop_Cons nth_Cons split:nat.splits) done lemma take_Suc_conv_app_nth: "i < length xs \<Longrightarrow> take (Suc i) xs = take i xs @ [xs!i]" apply (induct xs arbitrary: i, simp) apply (case_tac i, auto) done lemma drop_Suc_conv_tl: "i < length xs \<Longrightarrow> (xs!i) # (drop (Suc i) xs) = drop i xs" apply (induct xs arbitrary: i, simp) apply (case_tac i, auto) done lemma length_take [simp]: "length (take n xs) = min (length xs) n" by (induct n arbitrary: xs) (auto, case_tac xs, auto) lemma length_drop [simp]: "length (drop n xs) = (length xs - n)" by (induct n arbitrary: xs) (auto, case_tac xs, auto) lemma take_all [simp]: "length xs <= n ==> take n xs = xs" by (induct n arbitrary: xs) (auto, case_tac xs, auto) lemma drop_all [simp]: "length xs <= n ==> drop n xs = []" by (induct n arbitrary: xs) (auto, case_tac xs, auto) lemma take_append [simp]: "take n (xs @ ys) = (take n xs @ take (n - length xs) ys)" by (induct n arbitrary: xs) (auto, case_tac xs, auto) lemma drop_append [simp]: "drop n (xs @ ys) = drop n xs @ drop (n - length xs) ys" by (induct n arbitrary: xs) (auto, case_tac xs, auto) lemma take_take [simp]: "take n (take m xs) = take (min n m) xs" apply (induct m arbitrary: xs n, auto) apply (case_tac xs, auto) apply (case_tac n, auto) done lemma drop_drop [simp]: "drop n (drop m xs) = drop (n + m) xs" apply (induct m arbitrary: xs, auto) apply (case_tac xs, auto) done lemma take_drop: "take n (drop m xs) = drop m (take (n + m) xs)" apply (induct m arbitrary: xs n, auto) apply (case_tac xs, auto) done lemma drop_take: "drop n (take m xs) = take (m-n) (drop n xs)" apply(induct xs arbitrary: m n) apply simp apply(simp add: take_Cons drop_Cons split:nat.split) done lemma append_take_drop_id [simp]: "take n xs @ drop n xs = xs" apply (induct n arbitrary: xs, auto) apply (case_tac xs, auto) done lemma take_eq_Nil[simp]: "(take n xs = []) = (n = 0 \<or> xs = [])" apply(induct xs arbitrary: n) apply simp apply(simp add:take_Cons split:nat.split) done lemma drop_eq_Nil[simp]: "(drop n xs = []) = (length xs <= n)" apply(induct xs arbitrary: n) apply simp apply(simp add:drop_Cons split:nat.split) done lemma take_map: "take n (map f xs) = map f (take n xs)" apply (induct n arbitrary: xs, auto) apply (case_tac xs, auto) done lemma drop_map: "drop n (map f xs) = map f (drop n xs)" apply (induct n arbitrary: xs, auto) apply (case_tac xs, auto) done lemma rev_take: "rev (take i xs) = drop (length xs - i) (rev xs)" apply (induct xs arbitrary: i, auto) apply (case_tac i, auto) done lemma rev_drop: "rev (drop i xs) = take (length xs - i) (rev xs)" apply (induct xs arbitrary: i, auto) apply (case_tac i, auto) done lemma nth_take [simp]: "i < n ==> (take n xs)!i = xs!i" apply (induct xs arbitrary: i n, auto) apply (case_tac n, blast) apply (case_tac i, auto) done lemma nth_drop [simp]: "n + i <= length xs ==> (drop n xs)!i = xs!(n + i)" apply (induct n arbitrary: xs i, auto) apply (case_tac xs, auto) done lemma butlast_take: "n <= length xs ==> butlast (take n xs) = take (n - 1) xs" by (simp add: butlast_conv_take min_max.inf_absorb1 min_max.inf_absorb2) lemma butlast_drop: "butlast (drop n xs) = drop n (butlast xs)" by (simp add: butlast_conv_take drop_take add_ac) lemma take_butlast: "n < length xs ==> take n (butlast xs) = take n xs" by (simp add: butlast_conv_take min_max.inf_absorb1) lemma drop_butlast: "drop n (butlast xs) = butlast (drop n xs)" by (simp add: butlast_conv_take drop_take add_ac) lemma hd_drop_conv_nth: "\<lbrakk> xs \<noteq> []; n < length xs \<rbrakk> \<Longrightarrow> hd(drop n xs) = xs!n" by(simp add: hd_conv_nth) lemma set_take_subset_set_take: "m <= n \<Longrightarrow> set(take m xs) <= set(take n xs)" by(induct xs arbitrary: m n)(auto simp:take_Cons split:nat.split) lemma set_take_subset: "set(take n xs) \<subseteq> set xs" by(induct xs arbitrary: n)(auto simp:take_Cons split:nat.split) lemma set_drop_subset: "set(drop n xs) \<subseteq> set xs" by(induct xs arbitrary: n)(auto simp:drop_Cons split:nat.split) lemma set_drop_subset_set_drop: "m >= n \<Longrightarrow> set(drop m xs) <= set(drop n xs)" apply(induct xs arbitrary: m n) apply(auto simp:drop_Cons split:nat.split) apply (metis set_drop_subset subset_iff) done lemma in_set_takeD: "x : set(take n xs) \<Longrightarrow> x : set xs" using set_take_subset by fast lemma in_set_dropD: "x : set(drop n xs) \<Longrightarrow> x : set xs" using set_drop_subset by fast lemma append_eq_conv_conj: "(xs @ ys = zs) = (xs = take (length xs) zs \<and> ys = drop (length xs) zs)" apply (induct xs arbitrary: zs, simp, clarsimp) apply (case_tac zs, auto) done lemma take_add: "i+j \<le> length(xs) \<Longrightarrow> take (i+j) xs = take i xs @ take j (drop i xs)" apply (induct xs arbitrary: i, auto) apply (case_tac i, simp_all) done lemma append_eq_append_conv_if: "(xs\<^isub>1 @ xs\<^isub>2 = ys\<^isub>1 @ ys\<^isub>2) = (if size xs\<^isub>1 \<le> size ys\<^isub>1 then xs\<^isub>1 = take (size xs\<^isub>1) ys\<^isub>1 \<and> xs\<^isub>2 = drop (size xs\<^isub>1) ys\<^isub>1 @ ys\<^isub>2 else take (size ys\<^isub>1) xs\<^isub>1 = ys\<^isub>1 \<and> drop (size ys\<^isub>1) xs\<^isub>1 @ xs\<^isub>2 = ys\<^isub>2)" apply(induct xs\<^isub>1 arbitrary: ys\<^isub>1) apply simp apply(case_tac ys\<^isub>1) apply simp_all done lemma take_hd_drop: "n < length xs \<Longrightarrow> take n xs @ [hd (drop n xs)] = take (Suc n) xs" apply(induct xs arbitrary: n) apply simp apply(simp add:drop_Cons split:nat.split) done lemma id_take_nth_drop: "i < length xs \<Longrightarrow> xs = take i xs @ xs!i # drop (Suc i) xs" proof - assume si: "i < length xs" hence "xs = take (Suc i) xs @ drop (Suc i) xs" by auto moreover from si have "take (Suc i) xs = take i xs @ [xs!i]" apply (rule_tac take_Suc_conv_app_nth) by arith ultimately show ?thesis by auto qed lemma upd_conv_take_nth_drop: "i < length xs \<Longrightarrow> xs[i:=a] = take i xs @ a # drop (Suc i) xs" proof - assume i: "i < length xs" have "xs[i:=a] = (take i xs @ xs!i # drop (Suc i) xs)[i:=a]" by(rule arg_cong[OF id_take_nth_drop[OF i]]) also have "\<dots> = take i xs @ a # drop (Suc i) xs" using i by (simp add: list_update_append) finally show ?thesis . qed lemma nth_drop': "i < length xs \<Longrightarrow> xs ! i # drop (Suc i) xs = drop i xs" apply (induct i arbitrary: xs) apply (simp add: neq_Nil_conv) apply (erule exE)+ apply simp apply (case_tac xs) apply simp_all done subsubsection {* @{text takeWhile} and @{text dropWhile} *} lemma length_takeWhile_le: "length (takeWhile P xs) \<le> length xs" by (induct xs) auto lemma takeWhile_dropWhile_id [simp]: "takeWhile P xs @ dropWhile P xs = xs" by (induct xs) auto lemma takeWhile_append1 [simp]: "[| x:set xs; ~P(x)|] ==> takeWhile P (xs @ ys) = takeWhile P xs" by (induct xs) auto lemma takeWhile_append2 [simp]: "(!!x. x : set xs ==> P x) ==> takeWhile P (xs @ ys) = xs @ takeWhile P ys" by (induct xs) auto lemma takeWhile_tail: "\<not> P x ==> takeWhile P (xs @ (x#l)) = takeWhile P xs" by (induct xs) auto lemma takeWhile_nth: "j < length (takeWhile P xs) \<Longrightarrow> takeWhile P xs ! j = xs ! j" apply (subst (3) takeWhile_dropWhile_id[symmetric]) unfolding nth_append by auto lemma dropWhile_nth: "j < length (dropWhile P xs) \<Longrightarrow> dropWhile P xs ! j = xs ! (j + length (takeWhile P xs))" apply (subst (3) takeWhile_dropWhile_id[symmetric]) unfolding nth_append by auto lemma length_dropWhile_le: "length (dropWhile P xs) \<le> length xs" by (induct xs) auto lemma dropWhile_append1 [simp]: "[| x : set xs; ~P(x)|] ==> dropWhile P (xs @ ys) = (dropWhile P xs)@ys" by (induct xs) auto lemma dropWhile_append2 [simp]: "(!!x. x:set xs ==> P(x)) ==> dropWhile P (xs @ ys) = dropWhile P ys" by (induct xs) auto lemma set_takeWhileD: "x : set (takeWhile P xs) ==> x : set xs \<and> P x" by (induct xs) (auto split: split_if_asm) lemma takeWhile_eq_all_conv[simp]: "(takeWhile P xs = xs) = (\<forall>x \<in> set xs. P x)" by(induct xs, auto) lemma dropWhile_eq_Nil_conv[simp]: "(dropWhile P xs = []) = (\<forall>x \<in> set xs. P x)" by(induct xs, auto) lemma dropWhile_eq_Cons_conv: "(dropWhile P xs = y#ys) = (xs = takeWhile P xs @ y # ys & \<not> P y)" by(induct xs, auto) lemma distinct_takeWhile[simp]: "distinct xs ==> distinct (takeWhile P xs)" by (induct xs) (auto dest: set_takeWhileD) lemma distinct_dropWhile[simp]: "distinct xs ==> distinct (dropWhile P xs)" by (induct xs) auto lemma takeWhile_map: "takeWhile P (map f xs) = map f (takeWhile (P \<circ> f) xs)" by (induct xs) auto lemma dropWhile_map: "dropWhile P (map f xs) = map f (dropWhile (P \<circ> f) xs)" by (induct xs) auto lemma takeWhile_eq_take: "takeWhile P xs = take (length (takeWhile P xs)) xs" by (induct xs) auto lemma dropWhile_eq_drop: "dropWhile P xs = drop (length (takeWhile P xs)) xs" by (induct xs) auto lemma hd_dropWhile: "dropWhile P xs \<noteq> [] \<Longrightarrow> \<not> P (hd (dropWhile P xs))" using assms by (induct xs) auto lemma takeWhile_eq_filter: assumes "\<And> x. x \<in> set (dropWhile P xs) \<Longrightarrow> \<not> P x" shows "takeWhile P xs = filter P xs" proof - have A: "filter P xs = filter P (takeWhile P xs @ dropWhile P xs)" by simp have B: "filter P (dropWhile P xs) = []" unfolding filter_empty_conv using assms by blast have "filter P xs = takeWhile P xs" unfolding A filter_append B by (auto simp add: filter_id_conv dest: set_takeWhileD) thus ?thesis .. qed lemma takeWhile_eq_take_P_nth: "\<lbrakk> \<And> i. \<lbrakk> i < n ; i < length xs \<rbrakk> \<Longrightarrow> P (xs ! i) ; n < length xs \<Longrightarrow> \<not> P (xs ! n) \<rbrakk> \<Longrightarrow> takeWhile P xs = take n xs" proof (induct xs arbitrary: n) case (Cons x xs) thus ?case proof (cases n) case (Suc n') note this[simp] have "P x" using Cons.prems(1)[of 0] by simp moreover have "takeWhile P xs = take n' xs" proof (rule Cons.hyps) case goal1 thus "P (xs ! i)" using Cons.prems(1)[of "Suc i"] by simp next case goal2 thus ?case using Cons by auto qed ultimately show ?thesis by simp qed simp qed simp lemma nth_length_takeWhile: "length (takeWhile P xs) < length xs \<Longrightarrow> \<not> P (xs ! length (takeWhile P xs))" by (induct xs) auto lemma length_takeWhile_less_P_nth: assumes all: "\<And> i. i < j \<Longrightarrow> P (xs ! i)" and "j \<le> length xs" shows "j \<le> length (takeWhile P xs)" proof (rule classical) assume "\<not> ?thesis" hence "length (takeWhile P xs) < length xs" using assms by simp thus ?thesis using all `\<not> ?thesis` nth_length_takeWhile[of P xs] by auto qed text{* The following two lemmmas could be generalized to an arbitrary property. *} lemma takeWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow> takeWhile (\<lambda>y. y \<noteq> x) (rev xs) = rev (tl (dropWhile (\<lambda>y. y \<noteq> x) xs))" by(induct xs) (auto simp: takeWhile_tail[where l="[]"]) lemma dropWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow> dropWhile (\<lambda>y. y \<noteq> x) (rev xs) = x # rev (takeWhile (\<lambda>y. y \<noteq> x) xs)" apply(induct xs) apply simp apply auto apply(subst dropWhile_append2) apply auto done lemma takeWhile_not_last: "\<lbrakk> xs \<noteq> []; distinct xs\<rbrakk> \<Longrightarrow> takeWhile (\<lambda>y. y \<noteq> last xs) xs = butlast xs" apply(induct xs) apply simp apply(case_tac xs) apply(auto) done lemma takeWhile_cong [fundef_cong, recdef_cong]: "[| l = k; !!x. x : set l ==> P x = Q x |] ==> takeWhile P l = takeWhile Q k" by (induct k arbitrary: l) (simp_all) lemma dropWhile_cong [fundef_cong, recdef_cong]: "[| l = k; !!x. x : set l ==> P x = Q x |] ==> dropWhile P l = dropWhile Q k" by (induct k arbitrary: l, simp_all) subsubsection {* @{text zip} *} lemma zip_Nil [simp]: "zip [] ys = []" by (induct ys) auto lemma zip_Cons_Cons [simp]: "zip (x # xs) (y # ys) = (x, y) # zip xs ys" by simp declare zip_Cons [simp del] lemma zip_Cons1: "zip (x#xs) ys = (case ys of [] \<Rightarrow> [] | y#ys \<Rightarrow> (x,y)#zip xs ys)" by(auto split:list.split) lemma length_zip [simp]: "length (zip xs ys) = min (length xs) (length ys)" by (induct xs ys rule:list_induct2') auto lemma zip_obtain_same_length: assumes "\<And>zs ws n. length zs = length ws \<Longrightarrow> n = min (length xs) (length ys) \<Longrightarrow> zs = take n xs \<Longrightarrow> ws = take n ys \<Longrightarrow> P (zip zs ws)" shows "P (zip xs ys)" proof - let ?n = "min (length xs) (length ys)" have "P (zip (take ?n xs) (take ?n ys))" by (rule assms) simp_all moreover have "zip xs ys = zip (take ?n xs) (take ?n ys)" proof (induct xs arbitrary: ys) case Nil then show ?case by simp next case (Cons x xs) then show ?case by (cases ys) simp_all qed ultimately show ?thesis by simp qed lemma zip_append1: "zip (xs @ ys) zs = zip xs (take (length xs) zs) @ zip ys (drop (length xs) zs)" by (induct xs zs rule:list_induct2') auto lemma zip_append2: "zip xs (ys @ zs) = zip (take (length ys) xs) ys @ zip (drop (length ys) xs) zs" by (induct xs ys rule:list_induct2') auto lemma zip_append [simp]: "[| length xs = length us; length ys = length vs |] ==> zip (xs@ys) (us@vs) = zip xs us @ zip ys vs" by (simp add: zip_append1) lemma zip_rev: "length xs = length ys ==> zip (rev xs) (rev ys) = rev (zip xs ys)" by (induct rule:list_induct2, simp_all) lemma zip_map_map: "zip (map f xs) (map g ys) = map (\<lambda> (x, y). (f x, g y)) (zip xs ys)" proof (induct xs arbitrary: ys) case (Cons x xs) note Cons_x_xs = Cons.hyps show ?case proof (cases ys) case (Cons y ys') show ?thesis unfolding Cons using Cons_x_xs by simp qed simp qed simp lemma zip_map1: "zip (map f xs) ys = map (\<lambda>(x, y). (f x, y)) (zip xs ys)" using zip_map_map[of f xs "\<lambda>x. x" ys] by simp lemma zip_map2: "zip xs (map f ys) = map (\<lambda>(x, y). (x, f y)) (zip xs ys)" using zip_map_map[of "\<lambda>x. x" xs f ys] by simp lemma map_zip_map: "map f (zip (map g xs) ys) = map (%(x,y). f(g x, y)) (zip xs ys)" unfolding zip_map1 by auto lemma map_zip_map2: "map f (zip xs (map g ys)) = map (%(x,y). f(x, g y)) (zip xs ys)" unfolding zip_map2 by auto text{* Courtesy of Andreas Lochbihler: *} lemma zip_same_conv_map: "zip xs xs = map (\<lambda>x. (x, x)) xs" by(induct xs) auto lemma nth_zip [simp]: "[| i < length xs; i < length ys|] ==> (zip xs ys)!i = (xs!i, ys!i)" apply (induct ys arbitrary: i xs, simp) apply (case_tac xs) apply (simp_all add: nth.simps split: nat.split) done lemma set_zip: "set (zip xs ys) = {(xs!i, ys!i) | i. i < min (length xs) (length ys)}" by(simp add: set_conv_nth cong: rev_conj_cong) lemma zip_same: "((a,b) \<in> set (zip xs xs)) = (a \<in> set xs \<and> a = b)" by(induct xs) auto lemma zip_update: "zip (xs[i:=x]) (ys[i:=y]) = (zip xs ys)[i:=(x,y)]" by(rule sym, simp add: update_zip) lemma zip_replicate [simp]: "zip (replicate i x) (replicate j y) = replicate (min i j) (x,y)" apply (induct i arbitrary: j, auto) apply (case_tac j, auto) done lemma take_zip: "take n (zip xs ys) = zip (take n xs) (take n ys)" apply (induct n arbitrary: xs ys) apply simp apply (case_tac xs, simp) apply (case_tac ys, simp_all) done lemma drop_zip: "drop n (zip xs ys) = zip (drop n xs) (drop n ys)" apply (induct n arbitrary: xs ys) apply simp apply (case_tac xs, simp) apply (case_tac ys, simp_all) done lemma zip_takeWhile_fst: "zip (takeWhile P xs) ys = takeWhile (P \<circ> fst) (zip xs ys)" proof (induct xs arbitrary: ys) case (Cons x xs) thus ?case by (cases ys) auto qed simp lemma zip_takeWhile_snd: "zip xs (takeWhile P ys) = takeWhile (P \<circ> snd) (zip xs ys)" proof (induct xs arbitrary: ys) case (Cons x xs) thus ?case by (cases ys) auto qed simp lemma set_zip_leftD: "(x,y)\<in> set (zip xs ys) \<Longrightarrow> x \<in> set xs" by (induct xs ys rule:list_induct2') auto lemma set_zip_rightD: "(x,y)\<in> set (zip xs ys) \<Longrightarrow> y \<in> set ys" by (induct xs ys rule:list_induct2') auto lemma in_set_zipE: "(x,y) : set(zip xs ys) \<Longrightarrow> (\<lbrakk> x : set xs; y : set ys \<rbrakk> \<Longrightarrow> R) \<Longrightarrow> R" by(blast dest: set_zip_leftD set_zip_rightD) lemma zip_map_fst_snd: "zip (map fst zs) (map snd zs) = zs" by (induct zs) simp_all lemma zip_eq_conv: "length xs = length ys \<Longrightarrow> zip xs ys = zs \<longleftrightarrow> map fst zs = xs \<and> map snd zs = ys" by (auto simp add: zip_map_fst_snd) lemma distinct_zipI1: "distinct xs \<Longrightarrow> distinct (zip xs ys)" proof (induct xs arbitrary: ys) case (Cons x xs) show ?case proof (cases ys) case (Cons y ys') have "(x, y) \<notin> set (zip xs ys')" using Cons.prems by (auto simp: set_zip) thus ?thesis unfolding Cons zip_Cons_Cons distinct.simps using Cons.hyps Cons.prems by simp qed simp qed simp lemma distinct_zipI2: "distinct xs \<Longrightarrow> distinct (zip xs ys)" proof (induct xs arbitrary: ys) case (Cons x xs) show ?case proof (cases ys) case (Cons y ys') have "(x, y) \<notin> set (zip xs ys')" using Cons.prems by (auto simp: set_zip) thus ?thesis unfolding Cons zip_Cons_Cons distinct.simps using Cons.hyps Cons.prems by simp qed simp qed simp subsubsection {* @{text list_all2} *} lemma list_all2_lengthD [intro?]: "list_all2 P xs ys ==> length xs = length ys" by (simp add: list_all2_def) lemma list_all2_Nil [iff, code]: "list_all2 P [] ys = (ys = [])" by (simp add: list_all2_def) lemma list_all2_Nil2 [iff, code]: "list_all2 P xs [] = (xs = [])" by (simp add: list_all2_def) lemma list_all2_Cons [iff, code]: "list_all2 P (x # xs) (y # ys) = (P x y \<and> list_all2 P xs ys)" by (auto simp add: list_all2_def) lemma list_all2_Cons1: "list_all2 P (x # xs) ys = (\<exists>z zs. ys = z # zs \<and> P x z \<and> list_all2 P xs zs)" by (cases ys) auto lemma list_all2_Cons2: "list_all2 P xs (y # ys) = (\<exists>z zs. xs = z # zs \<and> P z y \<and> list_all2 P zs ys)" by (cases xs) auto lemma list_all2_rev [iff]: "list_all2 P (rev xs) (rev ys) = list_all2 P xs ys" by (simp add: list_all2_def zip_rev cong: conj_cong) lemma list_all2_rev1: "list_all2 P (rev xs) ys = list_all2 P xs (rev ys)" by (subst list_all2_rev [symmetric]) simp lemma list_all2_append1: "list_all2 P (xs @ ys) zs = (EX us vs. zs = us @ vs \<and> length us = length xs \<and> length vs = length ys \<and> list_all2 P xs us \<and> list_all2 P ys vs)" apply (simp add: list_all2_def zip_append1) apply (rule iffI) apply (rule_tac x = "take (length xs) zs" in exI) apply (rule_tac x = "drop (length xs) zs" in exI) apply (force split: nat_diff_split simp add: min_def, clarify) apply (simp add: ball_Un) done lemma list_all2_append2: "list_all2 P xs (ys @ zs) = (EX us vs. xs = us @ vs \<and> length us = length ys \<and> length vs = length zs \<and> list_all2 P us ys \<and> list_all2 P vs zs)" apply (simp add: list_all2_def zip_append2) apply (rule iffI) apply (rule_tac x = "take (length ys) xs" in exI) apply (rule_tac x = "drop (length ys) xs" in exI) apply (force split: nat_diff_split simp add: min_def, clarify) apply (simp add: ball_Un) done lemma list_all2_append: "length xs = length ys \<Longrightarrow> list_all2 P (xs@us) (ys@vs) = (list_all2 P xs ys \<and> list_all2 P us vs)" by (induct rule:list_induct2, simp_all) lemma list_all2_appendI [intro?, trans]: "\<lbrakk> list_all2 P a b; list_all2 P c d \<rbrakk> \<Longrightarrow> list_all2 P (a@c) (b@d)" by (simp add: list_all2_append list_all2_lengthD) lemma list_all2_conv_all_nth: "list_all2 P xs ys = (length xs = length ys \<and> (\<forall>i < length xs. P (xs!i) (ys!i)))" by (force simp add: list_all2_def set_zip) lemma list_all2_trans: assumes tr: "!!a b c. P1 a b ==> P2 b c ==> P3 a c" shows "!!bs cs. list_all2 P1 as bs ==> list_all2 P2 bs cs ==> list_all2 P3 as cs" (is "!!bs cs. PROP ?Q as bs cs") proof (induct as) fix x xs bs assume I1: "!!bs cs. PROP ?Q xs bs cs" show "!!cs. PROP ?Q (x # xs) bs cs" proof (induct bs) fix y ys cs assume I2: "!!cs. PROP ?Q (x # xs) ys cs" show "PROP ?Q (x # xs) (y # ys) cs" by (induct cs) (auto intro: tr I1 I2) qed simp qed simp lemma list_all2_all_nthI [intro?]: "length a = length b \<Longrightarrow> (\<And>n. n < length a \<Longrightarrow> P (a!n) (b!n)) \<Longrightarrow> list_all2 P a b" by (simp add: list_all2_conv_all_nth) lemma list_all2I: "\<forall>x \<in> set (zip a b). split P x \<Longrightarrow> length a = length b \<Longrightarrow> list_all2 P a b" by (simp add: list_all2_def) lemma list_all2_nthD: "\<lbrakk> list_all2 P xs ys; p < size xs \<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)" by (simp add: list_all2_conv_all_nth) lemma list_all2_nthD2: "\<lbrakk>list_all2 P xs ys; p < size ys\<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)" by (frule list_all2_lengthD) (auto intro: list_all2_nthD) lemma list_all2_map1: "list_all2 P (map f as) bs = list_all2 (\<lambda>x y. P (f x) y) as bs" by (simp add: list_all2_conv_all_nth) lemma list_all2_map2: "list_all2 P as (map f bs) = list_all2 (\<lambda>x y. P x (f y)) as bs" by (auto simp add: list_all2_conv_all_nth) lemma list_all2_refl [intro?]: "(\<And>x. P x x) \<Longrightarrow> list_all2 P xs xs" by (simp add: list_all2_conv_all_nth) lemma list_all2_update_cong: "\<lbrakk> i<size xs; list_all2 P xs ys; P x y \<rbrakk> \<Longrightarrow> list_all2 P (xs[i:=x]) (ys[i:=y])" by (simp add: list_all2_conv_all_nth nth_list_update) lemma list_all2_update_cong2: "\<lbrakk>list_all2 P xs ys; P x y; i < length ys\<rbrakk> \<Longrightarrow> list_all2 P (xs[i:=x]) (ys[i:=y])" by (simp add: list_all2_lengthD list_all2_update_cong) lemma list_all2_takeI [simp,intro?]: "list_all2 P xs ys \<Longrightarrow> list_all2 P (take n xs) (take n ys)" apply (induct xs arbitrary: n ys) apply simp apply (clarsimp simp add: list_all2_Cons1) apply (case_tac n) apply auto done lemma list_all2_dropI [simp,intro?]: "list_all2 P as bs \<Longrightarrow> list_all2 P (drop n as) (drop n bs)" apply (induct as arbitrary: n bs, simp) apply (clarsimp simp add: list_all2_Cons1) apply (case_tac n, simp, simp) done lemma list_all2_mono [intro?]: "list_all2 P xs ys \<Longrightarrow> (\<And>xs ys. P xs ys \<Longrightarrow> Q xs ys) \<Longrightarrow> list_all2 Q xs ys" apply (induct xs arbitrary: ys, simp) apply (case_tac ys, auto) done lemma list_all2_eq: "xs = ys \<longleftrightarrow> list_all2 (op =) xs ys" by (induct xs ys rule: list_induct2') auto subsubsection {* @{text foldl} and @{text foldr} *} lemma foldl_append [simp]: "foldl f a (xs @ ys) = foldl f (foldl f a xs) ys" by (induct xs arbitrary: a) auto lemma foldr_append[simp]: "foldr f (xs @ ys) a = foldr f xs (foldr f ys a)" by (induct xs) auto lemma foldr_map: "foldr g (map f xs) a = foldr (g o f) xs a" by(induct xs) simp_all text{* For efficient code generation: avoid intermediate list. *} lemma foldl_map[code_unfold]: "foldl g a (map f xs) = foldl (%a x. g a (f x)) a xs" by(induct xs arbitrary:a) simp_all lemma foldl_apply: assumes "\<And>x. x \<in> set xs \<Longrightarrow> f x \<circ> h = h \<circ> g x" shows "foldl (\<lambda>s x. f x s) (h s) xs = h (foldl (\<lambda>s x. g x s) s xs)" by (rule sym, insert assms, induct xs arbitrary: s) (simp_all add: expand_fun_eq) lemma foldl_cong [fundef_cong, recdef_cong]: "[| a = b; l = k; !!a x. x : set l ==> f a x = g a x |] ==> foldl f a l = foldl g b k" by (induct k arbitrary: a b l) simp_all lemma foldr_cong [fundef_cong, recdef_cong]: "[| a = b; l = k; !!a x. x : set l ==> f x a = g x a |] ==> foldr f l a = foldr g k b" by (induct k arbitrary: a b l) simp_all lemma foldl_fun_comm: assumes "\<And>x y s. f (f s x) y = f (f s y) x" shows "f (foldl f s xs) x = foldl f (f s x) xs" by (induct xs arbitrary: s) (simp_all add: assms) lemma (in semigroup_add) foldl_assoc: shows "foldl op+ (x+y) zs = x + (foldl op+ y zs)" by (induct zs arbitrary: y) (simp_all add:add_assoc) lemma (in monoid_add) foldl_absorb0: shows "x + (foldl op+ 0 zs) = foldl op+ x zs" by (induct zs) (simp_all add:foldl_assoc) lemma foldl_rev: assumes "\<And>x y s. f (f s x) y = f (f s y) x" shows "foldl f s (rev xs) = foldl f s xs" proof (induct xs arbitrary: s) case Nil then show ?case by simp next case (Cons x xs) with assms show ?case by (simp add: foldl_fun_comm) qed text{* The ``First Duality Theorem'' in Bird \& Wadler: *} lemma foldl_foldr1_lemma: "foldl op + a xs = a + foldr op + xs (0\<Colon>'a::monoid_add)" by (induct xs arbitrary: a) (auto simp:add_assoc) corollary foldl_foldr1: "foldl op + 0 xs = foldr op + xs (0\<Colon>'a::monoid_add)" by (simp add:foldl_foldr1_lemma) text{* The ``Third Duality Theorem'' in Bird \& Wadler: *} lemma foldr_foldl: "foldr f xs a = foldl (%x y. f y x) a (rev xs)" by (induct xs) auto lemma foldl_foldr: "foldl f a xs = foldr (%x y. f y x) (rev xs) a" by (simp add: foldr_foldl [of "%x y. f y x" "rev xs"]) lemma (in ab_semigroup_add) foldr_conv_foldl: "foldr op + xs a = foldl op + a xs" by (induct xs, auto simp add: foldl_assoc add_commute) text {* Note: @{text "n \<le> foldl (op +) n ns"} looks simpler, but is more difficult to use because it requires an additional transitivity step. *} lemma start_le_sum: "(m::nat) <= n ==> m <= foldl (op +) n ns" by (induct ns arbitrary: n) auto lemma elem_le_sum: "(n::nat) : set ns ==> n <= foldl (op +) 0 ns" by (force intro: start_le_sum simp add: in_set_conv_decomp) lemma sum_eq_0_conv [iff]: "(foldl (op +) (m::nat) ns = 0) = (m = 0 \<and> (\<forall>n \<in> set ns. n = 0))" by (induct ns arbitrary: m) auto lemma foldr_invariant: "\<lbrakk>Q x ; \<forall> x\<in> set xs. P x; \<forall> x y. P x \<and> Q y \<longrightarrow> Q (f x y) \<rbrakk> \<Longrightarrow> Q (foldr f xs x)" by (induct xs, simp_all) lemma foldl_invariant: "\<lbrakk>Q x ; \<forall> x\<in> set xs. P x; \<forall> x y. P x \<and> Q y \<longrightarrow> Q (f y x) \<rbrakk> \<Longrightarrow> Q (foldl f x xs)" by (induct xs arbitrary: x, simp_all) lemma foldl_weak_invariant: assumes "P s" and "\<And>s x. x \<in> set xs \<Longrightarrow> P s \<Longrightarrow> P (f s x)" shows "P (foldl f s xs)" using assms by (induct xs arbitrary: s) simp_all text {* @{const foldl} and @{const concat} *} lemma foldl_conv_concat: "foldl (op @) xs xss = xs @ concat xss" proof (induct xss arbitrary: xs) case Nil show ?case by simp next interpret monoid_add "op @" "[]" proof qed simp_all case Cons then show ?case by (simp add: foldl_absorb0) qed lemma concat_conv_foldl: "concat xss = foldl (op @) [] xss" by (simp add: foldl_conv_concat) text {* @{const Finite_Set.fold} and @{const foldl} *} lemma (in fun_left_comm) fold_set_remdups: "fold f y (set xs) = foldl (\<lambda>y x. f x y) y (remdups xs)" by (rule sym, induct xs arbitrary: y) (simp_all add: fold_fun_comm insert_absorb) lemma (in fun_left_comm_idem) fold_set: "fold f y (set xs) = foldl (\<lambda>y x. f x y) y xs" by (rule sym, induct xs arbitrary: y) (simp_all add: fold_fun_comm) lemma (in ab_semigroup_idem_mult) fold1_set: assumes "xs \<noteq> []" shows "fold1 times (set xs) = foldl times (hd xs) (tl xs)" proof - interpret fun_left_comm_idem times by (fact fun_left_comm_idem) from assms obtain y ys where xs: "xs = y # ys" by (cases xs) auto show ?thesis proof (cases "set ys = {}") case True with xs show ?thesis by simp next case False then have "fold1 times (insert y (set ys)) = fold times y (set ys)" by (simp only: finite_set fold1_eq_fold_idem) with xs show ?thesis by (simp add: fold_set mult_commute) qed qed lemma (in lattice) Inf_fin_set_fold [code_unfold]: "Inf_fin (set (x # xs)) = foldl inf x xs" proof - interpret ab_semigroup_idem_mult "inf :: 'a \<Rightarrow> 'a \<Rightarrow> 'a" by (fact ab_semigroup_idem_mult_inf) show ?thesis by (simp add: Inf_fin_def fold1_set del: set.simps) qed lemma (in lattice) Sup_fin_set_fold [code_unfold]: "Sup_fin (set (x # xs)) = foldl sup x xs" proof - interpret ab_semigroup_idem_mult "sup :: 'a \<Rightarrow> 'a \<Rightarrow> 'a" by (fact ab_semigroup_idem_mult_sup) show ?thesis by (simp add: Sup_fin_def fold1_set del: set.simps) qed lemma (in linorder) Min_fin_set_fold [code_unfold]: "Min (set (x # xs)) = foldl min x xs" proof - interpret ab_semigroup_idem_mult "min :: 'a \<Rightarrow> 'a \<Rightarrow> 'a" by (fact ab_semigroup_idem_mult_min) show ?thesis by (simp add: Min_def fold1_set del: set.simps) qed lemma (in linorder) Max_fin_set_fold [code_unfold]: "Max (set (x # xs)) = foldl max x xs" proof - interpret ab_semigroup_idem_mult "max :: 'a \<Rightarrow> 'a \<Rightarrow> 'a" by (fact ab_semigroup_idem_mult_max) show ?thesis by (simp add: Max_def fold1_set del: set.simps) qed lemma (in complete_lattice) Inf_set_fold [code_unfold]: "Inf (set xs) = foldl inf top xs" proof - interpret fun_left_comm_idem "inf :: 'a \<Rightarrow> 'a \<Rightarrow> 'a" by (fact fun_left_comm_idem_inf) show ?thesis by (simp add: Inf_fold_inf fold_set inf_commute) qed lemma (in complete_lattice) Sup_set_fold [code_unfold]: "Sup (set xs) = foldl sup bot xs" proof - interpret fun_left_comm_idem "sup :: 'a \<Rightarrow> 'a \<Rightarrow> 'a" by (fact fun_left_comm_idem_sup) show ?thesis by (simp add: Sup_fold_sup fold_set sup_commute) qed lemma (in complete_lattice) INFI_set_fold: "INFI (set xs) f = foldl (\<lambda>y x. inf (f x) y) top xs" unfolding INFI_def set_map [symmetric] Inf_set_fold foldl_map by (simp add: inf_commute) lemma (in complete_lattice) SUPR_set_fold: "SUPR (set xs) f = foldl (\<lambda>y x. sup (f x) y) bot xs" unfolding SUPR_def set_map [symmetric] Sup_set_fold foldl_map by (simp add: sup_commute) subsubsection {* List summation: @{const listsum} and @{text"\<Sum>"}*} lemma listsum_append [simp]: "listsum (xs @ ys) = listsum xs + listsum ys" by (induct xs) (simp_all add:add_assoc) lemma listsum_rev [simp]: fixes xs :: "'a\<Colon>comm_monoid_add list" shows "listsum (rev xs) = listsum xs" by (induct xs) (simp_all add:add_ac) lemma listsum_map_remove1: fixes f :: "'a \<Rightarrow> ('b::comm_monoid_add)" shows "x : set xs \<Longrightarrow> listsum(map f xs) = f x + listsum(map f (remove1 x xs))" by (induct xs)(auto simp add:add_ac) lemma list_size_conv_listsum: "list_size f xs = listsum (map f xs) + size xs" by(induct xs) auto lemma listsum_foldr: "listsum xs = foldr (op +) xs 0" by (induct xs) auto lemma length_concat: "length (concat xss) = listsum (map length xss)" by (induct xss) simp_all lemma listsum_map_filter: fixes f :: "'a \<Rightarrow> 'b \<Colon> comm_monoid_add" assumes "\<And> x. \<lbrakk> x \<in> set xs ; \<not> P x \<rbrakk> \<Longrightarrow> f x = 0" shows "listsum (map f (filter P xs)) = listsum (map f xs)" using assms by (induct xs) auto text{* For efficient code generation --- @{const listsum} is not tail recursive but @{const foldl} is. *} lemma listsum[code_unfold]: "listsum xs = foldl (op +) 0 xs" by(simp add:listsum_foldr foldl_foldr1) lemma distinct_listsum_conv_Setsum: "distinct xs \<Longrightarrow> listsum xs = Setsum(set xs)" by (induct xs) simp_all text{* Some syntactic sugar for summing a function over a list: *} syntax "_listsum" :: "pttrn => 'a list => 'b => 'b" ("(3SUM _<-_. _)" [0, 51, 10] 10) syntax (xsymbols) "_listsum" :: "pttrn => 'a list => 'b => 'b" ("(3\<Sum>_\<leftarrow>_. _)" [0, 51, 10] 10) syntax (HTML output) "_listsum" :: "pttrn => 'a list => 'b => 'b" ("(3\<Sum>_\<leftarrow>_. _)" [0, 51, 10] 10) translations -- {* Beware of argument permutation! *} "SUM x<-xs. b" == "CONST listsum (CONST map (%x. b) xs)" "\<Sum>x\<leftarrow>xs. b" == "CONST listsum (CONST map (%x. b) xs)" lemma listsum_triv: "(\<Sum>x\<leftarrow>xs. r) = of_nat (length xs) * r" by (induct xs) (simp_all add: left_distrib) lemma listsum_0 [simp]: "(\<Sum>x\<leftarrow>xs. 0) = 0" by (induct xs) (simp_all add: left_distrib) text{* For non-Abelian groups @{text xs} needs to be reversed on one side: *} lemma uminus_listsum_map: fixes f :: "'a \<Rightarrow> 'b\<Colon>ab_group_add" shows "- listsum (map f xs) = (listsum (map (uminus o f) xs))" by (induct xs) simp_all lemma listsum_addf: fixes f g :: "'a \<Rightarrow> 'b::comm_monoid_add" shows "(\<Sum>x\<leftarrow>xs. f x + g x) = listsum (map f xs) + listsum (map g xs)" by (induct xs) (simp_all add: algebra_simps) lemma listsum_subtractf: fixes f g :: "'a \<Rightarrow> 'b::ab_group_add" shows "(\<Sum>x\<leftarrow>xs. f x - g x) = listsum (map f xs) - listsum (map g xs)" by (induct xs) simp_all lemma listsum_const_mult: fixes f :: "'a \<Rightarrow> 'b::semiring_0" shows "(\<Sum>x\<leftarrow>xs. c * f x) = c * (\<Sum>x\<leftarrow>xs. f x)" by (induct xs, simp_all add: algebra_simps) lemma listsum_mult_const: fixes f :: "'a \<Rightarrow> 'b::semiring_0" shows "(\<Sum>x\<leftarrow>xs. f x * c) = (\<Sum>x\<leftarrow>xs. f x) * c" by (induct xs, simp_all add: algebra_simps) lemma listsum_abs: fixes xs :: "'a::ordered_ab_group_add_abs list" shows "\<bar>listsum xs\<bar> \<le> listsum (map abs xs)" by (induct xs, simp, simp add: order_trans [OF abs_triangle_ineq]) lemma listsum_mono: fixes f g :: "'a \<Rightarrow> 'b::{comm_monoid_add, ordered_ab_semigroup_add}" shows "(\<And>x. x \<in> set xs \<Longrightarrow> f x \<le> g x) \<Longrightarrow> (\<Sum>x\<leftarrow>xs. f x) \<le> (\<Sum>x\<leftarrow>xs. g x)" by (induct xs, simp, simp add: add_mono) subsubsection {* @{text upt} *} lemma upt_rec[code]: "[i..<j] = (if i<j then i#[Suc i..<j] else [])" -- {* simp does not terminate! *} by (induct j) auto lemmas upt_rec_number_of[simp] = upt_rec[of "number_of m" "number_of n", standard] lemma upt_conv_Nil [simp]: "j <= i ==> [i..<j] = []" by (subst upt_rec) simp lemma upt_eq_Nil_conv[simp]: "([i..<j] = []) = (j = 0 \<or> j <= i)" by(induct j)simp_all lemma upt_eq_Cons_conv: "([i..<j] = x#xs) = (i < j & i = x & [i+1..<j] = xs)" apply(induct j arbitrary: x xs) apply simp apply(clarsimp simp add: append_eq_Cons_conv) apply arith done lemma upt_Suc_append: "i <= j ==> [i..<(Suc j)] = [i..<j]@[j]" -- {* Only needed if @{text upt_Suc} is deleted from the simpset. *} by simp lemma upt_conv_Cons: "i < j ==> [i..<j] = i # [Suc i..<j]" by (simp add: upt_rec) lemma upt_add_eq_append: "i<=j ==> [i..<j+k] = [i..<j]@[j..<j+k]" -- {* LOOPS as a simprule, since @{text "j <= j"}. *} by (induct k) auto lemma length_upt [simp]: "length [i..<j] = j - i" by (induct j) (auto simp add: Suc_diff_le) lemma nth_upt [simp]: "i + k < j ==> [i..<j] ! k = i + k" apply (induct j) apply (auto simp add: less_Suc_eq nth_append split: nat_diff_split) done lemma hd_upt[simp]: "i < j \<Longrightarrow> hd[i..<j] = i" by(simp add:upt_conv_Cons) lemma last_upt[simp]: "i < j \<Longrightarrow> last[i..<j] = j - 1" apply(cases j) apply simp by(simp add:upt_Suc_append) lemma take_upt [simp]: "i+m <= n ==> take m [i..<n] = [i..<i+m]" apply (induct m arbitrary: i, simp) apply (subst upt_rec) apply (rule sym) apply (subst upt_rec) apply (simp del: upt.simps) done lemma drop_upt[simp]: "drop m [i..<j] = [i+m..<j]" apply(induct j) apply auto done lemma map_Suc_upt: "map Suc [m..<n] = [Suc m..<Suc n]" by (induct n) auto lemma nth_map_upt: "i < n-m ==> (map f [m..<n]) ! i = f(m+i)" apply (induct n m arbitrary: i rule: diff_induct) prefer 3 apply (subst map_Suc_upt[symmetric]) apply (auto simp add: less_diff_conv nth_upt) done lemma nth_take_lemma: "k <= length xs ==> k <= length ys ==> (!!i. i < k --> xs!i = ys!i) ==> take k xs = take k ys" apply (atomize, induct k arbitrary: xs ys) apply (simp_all add: less_Suc_eq_0_disj all_conj_distrib, clarify) txt {* Both lists must be non-empty *} apply (case_tac xs, simp) apply (case_tac ys, clarify) apply (simp (no_asm_use)) apply clarify txt {* prenexing's needed, not miniscoping *} apply (simp (no_asm_use) add: all_simps [symmetric] del: all_simps) apply blast done lemma nth_equalityI: "[| length xs = length ys; ALL i < length xs. xs!i = ys!i |] ==> xs = ys" apply (frule nth_take_lemma [OF le_refl eq_imp_le]) apply (simp_all add: take_all) done lemma map_nth: "map (\<lambda>i. xs ! i) [0..<length xs] = xs" by (rule nth_equalityI, auto) (* needs nth_equalityI *) lemma list_all2_antisym: "\<lbrakk> (\<And>x y. \<lbrakk>P x y; Q y x\<rbrakk> \<Longrightarrow> x = y); list_all2 P xs ys; list_all2 Q ys xs \<rbrakk> \<Longrightarrow> xs = ys" apply (simp add: list_all2_conv_all_nth) apply (rule nth_equalityI, blast, simp) done lemma take_equalityI: "(\<forall>i. take i xs = take i ys) ==> xs = ys" -- {* The famous take-lemma. *} apply (drule_tac x = "max (length xs) (length ys)" in spec) apply (simp add: le_max_iff_disj take_all) done lemma take_Cons': "take n (x # xs) = (if n = 0 then [] else x # take (n - 1) xs)" by (cases n) simp_all lemma drop_Cons': "drop n (x # xs) = (if n = 0 then x # xs else drop (n - 1) xs)" by (cases n) simp_all lemma nth_Cons': "(x # xs)!n = (if n = 0 then x else xs!(n - 1))" by (cases n) simp_all lemmas take_Cons_number_of = take_Cons'[of "number_of v",standard] lemmas drop_Cons_number_of = drop_Cons'[of "number_of v",standard] lemmas nth_Cons_number_of = nth_Cons'[of _ _ "number_of v",standard] declare take_Cons_number_of [simp] drop_Cons_number_of [simp] nth_Cons_number_of [simp] subsubsection {* @{text upto}: interval-list on @{typ int} *} (* FIXME make upto tail recursive? *) function upto :: "int \<Rightarrow> int \<Rightarrow> int list" ("(1[_../_])") where "upto i j = (if i \<le> j then i # [i+1..j] else [])" by auto termination by(relation "measure(%(i::int,j). nat(j - i + 1))") auto declare upto.simps[code, simp del] lemmas upto_rec_number_of[simp] = upto.simps[of "number_of m" "number_of n", standard] lemma upto_empty[simp]: "j < i \<Longrightarrow> [i..j] = []" by(simp add: upto.simps) lemma set_upto[simp]: "set[i..j] = {i..j}" apply(induct i j rule:upto.induct) apply(simp add: upto.simps simp_from_to) done subsubsection {* @{text "distinct"} and @{text remdups} *} lemma distinct_append [simp]: "distinct (xs @ ys) = (distinct xs \<and> distinct ys \<and> set xs \<inter> set ys = {})" by (induct xs) auto lemma distinct_rev[simp]: "distinct(rev xs) = distinct xs" by(induct xs) auto lemma set_remdups [simp]: "set (remdups xs) = set xs" by (induct xs) (auto simp add: insert_absorb) lemma distinct_remdups [iff]: "distinct (remdups xs)" by (induct xs) auto lemma distinct_remdups_id: "distinct xs ==> remdups xs = xs" by (induct xs, auto) lemma remdups_id_iff_distinct [simp]: "remdups xs = xs \<longleftrightarrow> distinct xs" by (metis distinct_remdups distinct_remdups_id) lemma finite_distinct_list: "finite A \<Longrightarrow> EX xs. set xs = A & distinct xs" by (metis distinct_remdups finite_list set_remdups) lemma remdups_eq_nil_iff [simp]: "(remdups x = []) = (x = [])" by (induct x, auto) lemma remdups_eq_nil_right_iff [simp]: "([] = remdups x) = (x = [])" by (induct x, auto) lemma length_remdups_leq[iff]: "length(remdups xs) <= length xs" by (induct xs) auto lemma length_remdups_eq[iff]: "(length (remdups xs) = length xs) = (remdups xs = xs)" apply(induct xs) apply auto apply(subgoal_tac "length (remdups xs) <= length xs") apply arith apply(rule length_remdups_leq) done lemma remdups_filter: "remdups(filter P xs) = filter P (remdups xs)" apply(induct xs) apply auto done lemma distinct_map: "distinct(map f xs) = (distinct xs & inj_on f (set xs))" by (induct xs) auto lemma distinct_filter [simp]: "distinct xs ==> distinct (filter P xs)" by (induct xs) auto lemma distinct_upt[simp]: "distinct[i..<j]" by (induct j) auto lemma distinct_upto[simp]: "distinct[i..j]" apply(induct i j rule:upto.induct) apply(subst upto.simps) apply(simp) done lemma distinct_take[simp]: "distinct xs \<Longrightarrow> distinct (take i xs)" apply(induct xs arbitrary: i) apply simp apply (case_tac i) apply simp_all apply(blast dest:in_set_takeD) done lemma distinct_drop[simp]: "distinct xs \<Longrightarrow> distinct (drop i xs)" apply(induct xs arbitrary: i) apply simp apply (case_tac i) apply simp_all done lemma distinct_list_update: assumes d: "distinct xs" and a: "a \<notin> set xs - {xs!i}" shows "distinct (xs[i:=a])" proof (cases "i < length xs") case True with a have "a \<notin> set (take i xs @ xs ! i # drop (Suc i) xs) - {xs!i}" apply (drule_tac id_take_nth_drop) by simp with d True show ?thesis apply (simp add: upd_conv_take_nth_drop) apply (drule subst [OF id_take_nth_drop]) apply assumption apply simp apply (cases "a = xs!i") apply simp by blast next case False with d show ?thesis by auto qed lemma distinct_concat: assumes "distinct xs" and "\<And> ys. ys \<in> set xs \<Longrightarrow> distinct ys" and "\<And> ys zs. \<lbrakk> ys \<in> set xs ; zs \<in> set xs ; ys \<noteq> zs \<rbrakk> \<Longrightarrow> set ys \<inter> set zs = {}" shows "distinct (concat xs)" using assms by (induct xs) auto text {* It is best to avoid this indexed version of distinct, but sometimes it is useful. *} lemma distinct_conv_nth: "distinct xs = (\<forall>i < size xs. \<forall>j < size xs. i \<noteq> j --> xs!i \<noteq> xs!j)" apply (induct xs, simp, simp) apply (rule iffI, clarsimp) apply (case_tac i) apply (case_tac j, simp) apply (simp add: set_conv_nth) apply (case_tac j) apply (clarsimp simp add: set_conv_nth, simp) apply (rule conjI) (*TOO SLOW apply (metis Zero_neq_Suc gr0_conv_Suc in_set_conv_nth lessI less_trans_Suc nth_Cons' nth_Cons_Suc) *) apply (clarsimp simp add: set_conv_nth) apply (erule_tac x = 0 in allE, simp) apply (erule_tac x = "Suc i" in allE, simp, clarsimp) (*TOO SLOW apply (metis Suc_Suc_eq lessI less_trans_Suc nth_Cons_Suc) *) apply (erule_tac x = "Suc i" in allE, simp) apply (erule_tac x = "Suc j" in allE, simp) done lemma nth_eq_iff_index_eq: "\<lbrakk> distinct xs; i < length xs; j < length xs \<rbrakk> \<Longrightarrow> (xs!i = xs!j) = (i = j)" by(auto simp: distinct_conv_nth) lemma distinct_card: "distinct xs ==> card (set xs) = size xs" by (induct xs) auto lemma card_distinct: "card (set xs) = size xs ==> distinct xs" proof (induct xs) case Nil thus ?case by simp next case (Cons x xs) show ?case proof (cases "x \<in> set xs") case False with Cons show ?thesis by simp next case True with Cons.prems have "card (set xs) = Suc (length xs)" by (simp add: card_insert_if split: split_if_asm) moreover have "card (set xs) \<le> length xs" by (rule card_length) ultimately have False by simp thus ?thesis .. qed qed lemma not_distinct_decomp: "~ distinct ws ==> EX xs ys zs y. ws = xs@[y]@ys@[y]@zs" apply (induct n == "length ws" arbitrary:ws) apply simp apply(case_tac ws) apply simp apply (simp split:split_if_asm) apply (metis Cons_eq_appendI eq_Nil_appendI split_list) done lemma length_remdups_concat: "length(remdups(concat xss)) = card(\<Union>xs \<in> set xss. set xs)" by(simp add: set_concat distinct_card[symmetric]) lemma length_remdups_card_conv: "length(remdups xs) = card(set xs)" proof - have xs: "concat[xs] = xs" by simp from length_remdups_concat[of "[xs]"] show ?thesis unfolding xs by simp qed subsubsection {* @{const insert} *} lemma in_set_insert [simp]: "x \<in> set xs \<Longrightarrow> List.insert x xs = xs" by (simp add: List.insert_def) lemma not_in_set_insert [simp]: "x \<notin> set xs \<Longrightarrow> List.insert x xs = x # xs" by (simp add: List.insert_def) lemma insert_Nil [simp]: "List.insert x [] = [x]" by simp lemma set_insert [simp]: "set (List.insert x xs) = insert x (set xs)" by (auto simp add: List.insert_def) lemma distinct_insert [simp]: "distinct xs \<Longrightarrow> distinct (List.insert x xs)" by (simp add: List.insert_def) subsubsection {* @{text remove1} *} lemma remove1_append: "remove1 x (xs @ ys) = (if x \<in> set xs then remove1 x xs @ ys else xs @ remove1 x ys)" by (induct xs) auto lemma in_set_remove1[simp]: "a \<noteq> b \<Longrightarrow> a : set(remove1 b xs) = (a : set xs)" apply (induct xs) apply auto done lemma set_remove1_subset: "set(remove1 x xs) <= set xs" apply(induct xs) apply simp apply simp apply blast done lemma set_remove1_eq [simp]: "distinct xs ==> set(remove1 x xs) = set xs - {x}" apply(induct xs) apply simp apply simp apply blast done lemma length_remove1: "length(remove1 x xs) = (if x : set xs then length xs - 1 else length xs)" apply (induct xs) apply (auto dest!:length_pos_if_in_set) done lemma remove1_filter_not[simp]: "\<not> P x \<Longrightarrow> remove1 x (filter P xs) = filter P xs" by(induct xs) auto lemma notin_set_remove1[simp]: "x ~: set xs ==> x ~: set(remove1 y xs)" apply(insert set_remove1_subset) apply fast done lemma distinct_remove1[simp]: "distinct xs ==> distinct(remove1 x xs)" by (induct xs) simp_all subsubsection {* @{text removeAll} *} lemma removeAll_filter_not_eq: "removeAll x = filter (\<lambda>y. x \<noteq> y)" proof fix xs show "removeAll x xs = filter (\<lambda>y. x \<noteq> y) xs" by (induct xs) auto qed lemma removeAll_append[simp]: "removeAll x (xs @ ys) = removeAll x xs @ removeAll x ys" by (induct xs) auto lemma set_removeAll[simp]: "set(removeAll x xs) = set xs - {x}" by (induct xs) auto lemma removeAll_id[simp]: "x \<notin> set xs \<Longrightarrow> removeAll x xs = xs" by (induct xs) auto (* Needs count:: 'a \<Rightarrow> a' list \<Rightarrow> nat lemma length_removeAll: "length(removeAll x xs) = length xs - count x xs" *) lemma removeAll_filter_not[simp]: "\<not> P x \<Longrightarrow> removeAll x (filter P xs) = filter P xs" by(induct xs) auto lemma distinct_removeAll: "distinct xs \<Longrightarrow> distinct (removeAll x xs)" by (simp add: removeAll_filter_not_eq) lemma distinct_remove1_removeAll: "distinct xs ==> remove1 x xs = removeAll x xs" by (induct xs) simp_all lemma map_removeAll_inj_on: "inj_on f (insert x (set xs)) \<Longrightarrow> map f (removeAll x xs) = removeAll (f x) (map f xs)" by (induct xs) (simp_all add:inj_on_def) lemma map_removeAll_inj: "inj f \<Longrightarrow> map f (removeAll x xs) = removeAll (f x) (map f xs)" by(metis map_removeAll_inj_on subset_inj_on subset_UNIV) subsubsection {* @{text replicate} *} lemma length_replicate [simp]: "length (replicate n x) = n" by (induct n) auto lemma map_replicate [simp]: "map f (replicate n x) = replicate n (f x)" by (induct n) auto lemma map_replicate_const: "map (\<lambda> x. k) lst = replicate (length lst) k" by (induct lst) auto lemma replicate_app_Cons_same: "(replicate n x) @ (x # xs) = x # replicate n x @ xs" by (induct n) auto lemma rev_replicate [simp]: "rev (replicate n x) = replicate n x" apply (induct n, simp) apply (simp add: replicate_app_Cons_same) done lemma replicate_add: "replicate (n + m) x = replicate n x @ replicate m x" by (induct n) auto text{* Courtesy of Matthias Daum: *} lemma append_replicate_commute: "replicate n x @ replicate k x = replicate k x @ replicate n x" apply (simp add: replicate_add [THEN sym]) apply (simp add: add_commute) done text{* Courtesy of Andreas Lochbihler: *} lemma filter_replicate: "filter P (replicate n x) = (if P x then replicate n x else [])" by(induct n) auto lemma hd_replicate [simp]: "n \<noteq> 0 ==> hd (replicate n x) = x" by (induct n) auto lemma tl_replicate [simp]: "n \<noteq> 0 ==> tl (replicate n x) = replicate (n - 1) x" by (induct n) auto lemma last_replicate [simp]: "n \<noteq> 0 ==> last (replicate n x) = x" by (atomize (full), induct n) auto lemma nth_replicate[simp]: "i < n ==> (replicate n x)!i = x" apply (induct n arbitrary: i, simp) apply (simp add: nth_Cons split: nat.split) done text{* Courtesy of Matthias Daum (2 lemmas): *} lemma take_replicate[simp]: "take i (replicate k x) = replicate (min i k) x" apply (case_tac "k \<le> i") apply (simp add: min_def) apply (drule not_leE) apply (simp add: min_def) apply (subgoal_tac "replicate k x = replicate i x @ replicate (k - i) x") apply simp apply (simp add: replicate_add [symmetric]) done lemma drop_replicate[simp]: "drop i (replicate k x) = replicate (k-i) x" apply (induct k arbitrary: i) apply simp apply clarsimp apply (case_tac i) apply simp apply clarsimp done lemma set_replicate_Suc: "set (replicate (Suc n) x) = {x}" by (induct n) auto lemma set_replicate [simp]: "n \<noteq> 0 ==> set (replicate n x) = {x}" by (fast dest!: not0_implies_Suc intro!: set_replicate_Suc) lemma set_replicate_conv_if: "set (replicate n x) = (if n = 0 then {} else {x})" by auto lemma in_set_replicateD: "x : set (replicate n y) ==> x = y" by (simp add: set_replicate_conv_if split: split_if_asm) lemma replicate_append_same: "replicate i x @ [x] = x # replicate i x" by (induct i) simp_all lemma map_replicate_trivial: "map (\<lambda>i. x) [0..<i] = replicate i x" by (induct i) (simp_all add: replicate_append_same) lemma concat_replicate_trivial[simp]: "concat (replicate i []) = []" by (induct i) (auto simp add: map_replicate_const) lemma replicate_empty[simp]: "(replicate n x = []) \<longleftrightarrow> n=0" by (induct n) auto lemma empty_replicate[simp]: "([] = replicate n x) \<longleftrightarrow> n=0" by (induct n) auto lemma replicate_eq_replicate[simp]: "(replicate m x = replicate n y) \<longleftrightarrow> (m=n & (m\<noteq>0 \<longrightarrow> x=y))" apply(induct m arbitrary: n) apply simp apply(induct_tac n) apply auto done subsubsection{*@{text rotate1} and @{text rotate}*} lemma rotate_simps[simp]: "rotate1 [] = [] \<and> rotate1 (x#xs) = xs @ [x]" by(simp add:rotate1_def) lemma rotate0[simp]: "rotate 0 = id" by(simp add:rotate_def) lemma rotate_Suc[simp]: "rotate (Suc n) xs = rotate1(rotate n xs)" by(simp add:rotate_def) lemma rotate_add: "rotate (m+n) = rotate m o rotate n" by(simp add:rotate_def funpow_add) lemma rotate_rotate: "rotate m (rotate n xs) = rotate (m+n) xs" by(simp add:rotate_add) lemma rotate1_rotate_swap: "rotate1 (rotate n xs) = rotate n (rotate1 xs)" by(simp add:rotate_def funpow_swap1) lemma rotate1_length01[simp]: "length xs <= 1 \<Longrightarrow> rotate1 xs = xs" by(cases xs) simp_all lemma rotate_length01[simp]: "length xs <= 1 \<Longrightarrow> rotate n xs = xs" apply(induct n) apply simp apply (simp add:rotate_def) done lemma rotate1_hd_tl: "xs \<noteq> [] \<Longrightarrow> rotate1 xs = tl xs @ [hd xs]" by(simp add:rotate1_def split:list.split) lemma rotate_drop_take: "rotate n xs = drop (n mod length xs) xs @ take (n mod length xs) xs" apply(induct n) apply simp apply(simp add:rotate_def) apply(cases "xs = []") apply (simp) apply(case_tac "n mod length xs = 0") apply(simp add:mod_Suc) apply(simp add: rotate1_hd_tl drop_Suc take_Suc) apply(simp add:mod_Suc rotate1_hd_tl drop_Suc[symmetric] drop_tl[symmetric] take_hd_drop linorder_not_le) done lemma rotate_conv_mod: "rotate n xs = rotate (n mod length xs) xs" by(simp add:rotate_drop_take) lemma rotate_id[simp]: "n mod length xs = 0 \<Longrightarrow> rotate n xs = xs" by(simp add:rotate_drop_take) lemma length_rotate1[simp]: "length(rotate1 xs) = length xs" by(simp add:rotate1_def split:list.split) lemma length_rotate[simp]: "length(rotate n xs) = length xs" by (induct n arbitrary: xs) (simp_all add:rotate_def) lemma distinct1_rotate[simp]: "distinct(rotate1 xs) = distinct xs" by(simp add:rotate1_def split:list.split) blast lemma distinct_rotate[simp]: "distinct(rotate n xs) = distinct xs" by (induct n) (simp_all add:rotate_def) lemma rotate_map: "rotate n (map f xs) = map f (rotate n xs)" by(simp add:rotate_drop_take take_map drop_map) lemma set_rotate1[simp]: "set(rotate1 xs) = set xs" by(simp add:rotate1_def split:list.split) lemma set_rotate[simp]: "set(rotate n xs) = set xs" by (induct n) (simp_all add:rotate_def) lemma rotate1_is_Nil_conv[simp]: "(rotate1 xs = []) = (xs = [])" by(simp add:rotate1_def split:list.split) lemma rotate_is_Nil_conv[simp]: "(rotate n xs = []) = (xs = [])" by (induct n) (simp_all add:rotate_def) lemma rotate_rev: "rotate n (rev xs) = rev(rotate (length xs - (n mod length xs)) xs)" apply(simp add:rotate_drop_take rev_drop rev_take) apply(cases "length xs = 0") apply simp apply(cases "n mod length xs = 0") apply simp apply(simp add:rotate_drop_take rev_drop rev_take) done lemma hd_rotate_conv_nth: "xs \<noteq> [] \<Longrightarrow> hd(rotate n xs) = xs!(n mod length xs)" apply(simp add:rotate_drop_take hd_append hd_drop_conv_nth hd_conv_nth) apply(subgoal_tac "length xs \<noteq> 0") prefer 2 apply simp using mod_less_divisor[of "length xs" n] by arith subsubsection {* @{text sublist} --- a generalization of @{text nth} to sets *} lemma sublist_empty [simp]: "sublist xs {} = []" by (auto simp add: sublist_def) lemma sublist_nil [simp]: "sublist [] A = []" by (auto simp add: sublist_def) lemma length_sublist: "length(sublist xs I) = card{i. i < length xs \<and> i : I}" by(simp add: sublist_def length_filter_conv_card cong:conj_cong) lemma sublist_shift_lemma_Suc: "map fst (filter (%p. P(Suc(snd p))) (zip xs is)) = map fst (filter (%p. P(snd p)) (zip xs (map Suc is)))" apply(induct xs arbitrary: "is") apply simp apply (case_tac "is") apply simp apply simp done lemma sublist_shift_lemma: "map fst [p<-zip xs [i..<i + length xs] . snd p : A] = map fst [p<-zip xs [0..<length xs] . snd p + i : A]" by (induct xs rule: rev_induct) (simp_all add: add_commute) lemma sublist_append: "sublist (l @ l') A = sublist l A @ sublist l' {j. j + length l : A}" apply (unfold sublist_def) apply (induct l' rule: rev_induct, simp) apply (simp add: upt_add_eq_append[of 0] zip_append sublist_shift_lemma) apply (simp add: add_commute) done lemma sublist_Cons: "sublist (x # l) A = (if 0:A then [x] else []) @ sublist l {j. Suc j : A}" apply (induct l rule: rev_induct) apply (simp add: sublist_def) apply (simp del: append_Cons add: append_Cons[symmetric] sublist_append) done lemma set_sublist: "set(sublist xs I) = {xs!i|i. i<size xs \<and> i \<in> I}" apply(induct xs arbitrary: I) apply(auto simp: sublist_Cons nth_Cons split:nat.split dest!: gr0_implies_Suc) done lemma set_sublist_subset: "set(sublist xs I) \<subseteq> set xs" by(auto simp add:set_sublist) lemma notin_set_sublistI[simp]: "x \<notin> set xs \<Longrightarrow> x \<notin> set(sublist xs I)" by(auto simp add:set_sublist) lemma in_set_sublistD: "x \<in> set(sublist xs I) \<Longrightarrow> x \<in> set xs" by(auto simp add:set_sublist) lemma sublist_singleton [simp]: "sublist [x] A = (if 0 : A then [x] else [])" by (simp add: sublist_Cons) lemma distinct_sublistI[simp]: "distinct xs \<Longrightarrow> distinct(sublist xs I)" apply(induct xs arbitrary: I) apply simp apply(auto simp add:sublist_Cons) done lemma sublist_upt_eq_take [simp]: "sublist l {..<n} = take n l" apply (induct l rule: rev_induct, simp) apply (simp split: nat_diff_split add: sublist_append) done lemma filter_in_sublist: "distinct xs \<Longrightarrow> filter (%x. x \<in> set(sublist xs s)) xs = sublist xs s" proof (induct xs arbitrary: s) case Nil thus ?case by simp next case (Cons a xs) moreover hence "!x. x: set xs \<longrightarrow> x \<noteq> a" by auto ultimately show ?case by(simp add: sublist_Cons cong:filter_cong) qed subsubsection {* @{const splice} *} lemma splice_Nil2 [simp, code]: "splice xs [] = xs" by (cases xs) simp_all lemma splice_Cons_Cons [simp, code]: "splice (x#xs) (y#ys) = x # y # splice xs ys" by simp declare splice.simps(2) [simp del, code del] lemma length_splice[simp]: "length(splice xs ys) = length xs + length ys" apply(induct xs arbitrary: ys) apply simp apply(case_tac ys) apply auto done subsubsection {* Transpose *} function transpose where "transpose [] = []" | "transpose ([] # xss) = transpose xss" | "transpose ((x#xs) # xss) = (x # [h. (h#t) \<leftarrow> xss]) # transpose (xs # [t. (h#t) \<leftarrow> xss])" by pat_completeness auto lemma transpose_aux_filter_head: "concat (map (list_case [] (\<lambda>h t. [h])) xss) = map (\<lambda>xs. hd xs) [ys\<leftarrow>xss . ys \<noteq> []]" by (induct xss) (auto split: list.split) lemma transpose_aux_filter_tail: "concat (map (list_case [] (\<lambda>h t. [t])) xss) = map (\<lambda>xs. tl xs) [ys\<leftarrow>xss . ys \<noteq> []]" by (induct xss) (auto split: list.split) lemma transpose_aux_max: "max (Suc (length xs)) (foldr (\<lambda>xs. max (length xs)) xss 0) = Suc (max (length xs) (foldr (\<lambda>x. max (length x - Suc 0)) [ys\<leftarrow>xss . ys\<noteq>[]] 0))" (is "max _ ?foldB = Suc (max _ ?foldA)") proof (cases "[ys\<leftarrow>xss . ys\<noteq>[]] = []") case True hence "foldr (\<lambda>xs. max (length xs)) xss 0 = 0" proof (induct xss) case (Cons x xs) moreover hence "x = []" by (cases x) auto ultimately show ?case by auto qed simp thus ?thesis using True by simp next case False have foldA: "?foldA = foldr (\<lambda>x. max (length x)) [ys\<leftarrow>xss . ys \<noteq> []] 0 - 1" by (induct xss) auto have foldB: "?foldB = foldr (\<lambda>x. max (length x)) [ys\<leftarrow>xss . ys \<noteq> []] 0" by (induct xss) auto have "0 < ?foldB" proof - from False obtain z zs where zs: "[ys\<leftarrow>xss . ys \<noteq> []] = z#zs" by (auto simp: neq_Nil_conv) hence "z \<in> set ([ys\<leftarrow>xss . ys \<noteq> []])" by auto hence "z \<noteq> []" by auto thus ?thesis unfolding foldB zs by (auto simp: max_def intro: less_le_trans) qed thus ?thesis unfolding foldA foldB max_Suc_Suc[symmetric] by simp qed termination transpose by (relation "measure (\<lambda>xs. foldr (\<lambda>xs. max (length xs)) xs 0 + length xs)") (auto simp: transpose_aux_filter_tail foldr_map comp_def transpose_aux_max less_Suc_eq_le) lemma transpose_empty: "(transpose xs = []) \<longleftrightarrow> (\<forall>x \<in> set xs. x = [])" by (induct rule: transpose.induct) simp_all lemma length_transpose: fixes xs :: "'a list list" shows "length (transpose xs) = foldr (\<lambda>xs. max (length xs)) xs 0" by (induct rule: transpose.induct) (auto simp: transpose_aux_filter_tail foldr_map comp_def transpose_aux_max max_Suc_Suc[symmetric] simp del: max_Suc_Suc) lemma nth_transpose: fixes xs :: "'a list list" assumes "i < length (transpose xs)" shows "transpose xs ! i = map (\<lambda>xs. xs ! i) [ys \<leftarrow> xs. i < length ys]" using assms proof (induct arbitrary: i rule: transpose.induct) case (3 x xs xss) def XS == "(x # xs) # xss" hence [simp]: "XS \<noteq> []" by auto thus ?case proof (cases i) case 0 thus ?thesis by (simp add: transpose_aux_filter_head hd_conv_nth) next case (Suc j) have *: "\<And>xss. xs # map tl xss = map tl ((x#xs)#xss)" by simp have **: "\<And>xss. (x#xs) # filter (\<lambda>ys. ys \<noteq> []) xss = filter (\<lambda>ys. ys \<noteq> []) ((x#xs)#xss)" by simp { fix x have "Suc j < length x \<longleftrightarrow> x \<noteq> [] \<and> j < length x - Suc 0" by (cases x) simp_all } note *** = this have j_less: "j < length (transpose (xs # concat (map (list_case [] (\<lambda>h t. [t])) xss)))" using "3.prems" by (simp add: transpose_aux_filter_tail length_transpose Suc) show ?thesis unfolding transpose.simps `i = Suc j` nth_Cons_Suc "3.hyps"[OF j_less] apply (auto simp: transpose_aux_filter_tail filter_map comp_def length_transpose * ** *** XS_def[symmetric]) apply (rule_tac y=x in list.exhaust) by auto qed qed simp_all lemma transpose_map_map: "transpose (map (map f) xs) = map (map f) (transpose xs)" proof (rule nth_equalityI, safe) have [simp]: "length (transpose (map (map f) xs)) = length (transpose xs)" by (simp add: length_transpose foldr_map comp_def) show "length (transpose (map (map f) xs)) = length (map (map f) (transpose xs))" by simp fix i assume "i < length (transpose (map (map f) xs))" thus "transpose (map (map f) xs) ! i = map (map f) (transpose xs) ! i" by (simp add: nth_transpose filter_map comp_def) qed subsubsection {* (In)finiteness *} lemma finite_maxlen: "finite (M::'a list set) ==> EX n. ALL s:M. size s < n" proof (induct rule: finite.induct) case emptyI show ?case by simp next case (insertI M xs) then obtain n where "\<forall>s\<in>M. length s < n" by blast hence "ALL s:insert xs M. size s < max n (size xs) + 1" by auto thus ?case .. qed lemma finite_lists_length_eq: assumes "finite A" shows "finite {xs. set xs \<subseteq> A \<and> length xs = n}" (is "finite (?S n)") proof(induct n) case 0 show ?case by simp next case (Suc n) have "?S (Suc n) = (\<Union>x\<in>A. (\<lambda>xs. x#xs) ` ?S n)" by (auto simp:length_Suc_conv) then show ?case using `finite A` by (auto intro: finite_imageI Suc) (* FIXME metis? *) qed lemma finite_lists_length_le: assumes "finite A" shows "finite {xs. set xs \<subseteq> A \<and> length xs \<le> n}" (is "finite ?S") proof- have "?S = (\<Union>n\<in>{0..n}. {xs. set xs \<subseteq> A \<and> length xs = n})" by auto thus ?thesis by (auto intro: finite_lists_length_eq[OF `finite A`]) qed lemma infinite_UNIV_listI: "~ finite(UNIV::'a list set)" apply(rule notI) apply(drule finite_maxlen) apply (metis UNIV_I length_replicate less_not_refl) done subsection {* Sorting *} text{* Currently it is not shown that @{const sort} returns a permutation of its input because the nicest proof is via multisets, which are not yet available. Alternatively one could define a function that counts the number of occurrences of an element in a list and use that instead of multisets to state the correctness property. *} context linorder begin lemma length_insert[simp] : "length (insort_key f x xs) = Suc (length xs)" by (induct xs, auto) lemma insort_left_comm: "insort x (insort y xs) = insort y (insort x xs)" by (induct xs) auto lemma fun_left_comm_insort: "fun_left_comm insort" proof qed (fact insort_left_comm) lemma sort_key_simps [simp]: "sort_key f [] = []" "sort_key f (x#xs) = insort_key f x (sort_key f xs)" by (simp_all add: sort_key_def) lemma sort_foldl_insort: "sort xs = foldl (\<lambda>ys x. insort x ys) [] xs" by (simp add: sort_key_def foldr_foldl foldl_rev insort_left_comm) lemma length_sort[simp]: "length (sort_key f xs) = length xs" by (induct xs, auto) lemma sorted_Cons: "sorted (x#xs) = (sorted xs & (ALL y:set xs. x <= y))" apply(induct xs arbitrary: x) apply simp by simp (blast intro: order_trans) lemma sorted_append: "sorted (xs@ys) = (sorted xs & sorted ys & (\<forall>x \<in> set xs. \<forall>y \<in> set ys. x\<le>y))" by (induct xs) (auto simp add:sorted_Cons) lemma sorted_nth_mono: "sorted xs \<Longrightarrow> i \<le> j \<Longrightarrow> j < length xs \<Longrightarrow> xs!i \<le> xs!j" by (induct xs arbitrary: i j) (auto simp:nth_Cons' sorted_Cons) lemma sorted_rev_nth_mono: "sorted (rev xs) \<Longrightarrow> i \<le> j \<Longrightarrow> j < length xs \<Longrightarrow> xs!j \<le> xs!i" using sorted_nth_mono[ of "rev xs" "length xs - j - 1" "length xs - i - 1"] rev_nth[of "length xs - i - 1" "xs"] rev_nth[of "length xs - j - 1" "xs"] by auto lemma sorted_nth_monoI: "(\<And> i j. \<lbrakk> i \<le> j ; j < length xs \<rbrakk> \<Longrightarrow> xs ! i \<le> xs ! j) \<Longrightarrow> sorted xs" proof (induct xs) case (Cons x xs) have "sorted xs" proof (rule Cons.hyps) fix i j assume "i \<le> j" and "j < length xs" with Cons.prems[of "Suc i" "Suc j"] show "xs ! i \<le> xs ! j" by auto qed moreover { fix y assume "y \<in> set xs" then obtain j where "j < length xs" and "xs ! j = y" unfolding in_set_conv_nth by blast with Cons.prems[of 0 "Suc j"] have "x \<le> y" by auto } ultimately show ?case unfolding sorted_Cons by auto qed simp lemma sorted_equals_nth_mono: "sorted xs = (\<forall>j < length xs. \<forall>i \<le> j. xs ! i \<le> xs ! j)" by (auto intro: sorted_nth_monoI sorted_nth_mono) lemma set_insort: "set(insort_key f x xs) = insert x (set xs)" by (induct xs) auto lemma set_sort[simp]: "set(sort_key f xs) = set xs" by (induct xs) (simp_all add:set_insort) lemma distinct_insort: "distinct (insort_key f x xs) = (x \<notin> set xs \<and> distinct xs)" by(induct xs)(auto simp:set_insort) lemma distinct_sort[simp]: "distinct (sort_key f xs) = distinct xs" by(induct xs)(simp_all add:distinct_insort set_sort) lemma sorted_insort_key: "sorted (map f (insort_key f x xs)) = sorted (map f xs)" by(induct xs)(auto simp:sorted_Cons set_insort) lemma sorted_insort: "sorted (insort x xs) = sorted xs" using sorted_insort_key[where f="\<lambda>x. x"] by simp theorem sorted_sort_key[simp]: "sorted (map f (sort_key f xs))" by(induct xs)(auto simp:sorted_insort_key) theorem sorted_sort[simp]: "sorted (sort xs)" by(induct xs)(auto simp:sorted_insort) lemma insort_is_Cons: "\<forall>x\<in>set xs. f a \<le> f x \<Longrightarrow> insort_key f a xs = a # xs" by (cases xs) auto lemma sorted_remove1: "sorted xs \<Longrightarrow> sorted (remove1 a xs)" by(induct xs)(auto simp add: sorted_Cons) lemma insort_key_remove1: "\<lbrakk> a \<in> set xs; sorted (map f xs) ; inj_on f (set xs) \<rbrakk> \<Longrightarrow> insort_key f a (remove1 a xs) = xs" proof (induct xs) case (Cons x xs) thus ?case proof (cases "x = a") case False hence "f x \<noteq> f a" using Cons.prems by auto hence "f x < f a" using Cons.prems by (auto simp: sorted_Cons) thus ?thesis using Cons by (auto simp: sorted_Cons insort_is_Cons) qed (auto simp: sorted_Cons insort_is_Cons) qed simp lemma insort_remove1: "\<lbrakk> a \<in> set xs; sorted xs \<rbrakk> \<Longrightarrow> insort a (remove1 a xs) = xs" using insort_key_remove1[where f="\<lambda>x. x"] by simp lemma sorted_remdups[simp]: "sorted l \<Longrightarrow> sorted (remdups l)" by (induct l) (auto simp: sorted_Cons) lemma sorted_distinct_set_unique: assumes "sorted xs" "distinct xs" "sorted ys" "distinct ys" "set xs = set ys" shows "xs = ys" proof - from assms have 1: "length xs = length ys" by (auto dest!: distinct_card) from assms show ?thesis proof(induct rule:list_induct2[OF 1]) case 1 show ?case by simp next case 2 thus ?case by (simp add:sorted_Cons) (metis Diff_insert_absorb antisym insertE insert_iff) qed qed lemma map_sorted_distinct_set_unique: assumes "inj_on f (set xs \<union> set ys)" assumes "sorted (map f xs)" "distinct (map f xs)" "sorted (map f ys)" "distinct (map f ys)" assumes "set xs = set ys" shows "xs = ys" proof - from assms have "map f xs = map f ys" by (simp add: sorted_distinct_set_unique) moreover with `inj_on f (set xs \<union> set ys)` show "xs = ys" by (blast intro: map_inj_on) qed lemma finite_sorted_distinct_unique: shows "finite A \<Longrightarrow> EX! xs. set xs = A & sorted xs & distinct xs" apply(drule finite_distinct_list) apply clarify apply(rule_tac a="sort xs" in ex1I) apply (auto simp: sorted_distinct_set_unique) done lemma sorted_take: "sorted xs \<Longrightarrow> sorted (take n xs)" proof (induct xs arbitrary: n rule: sorted.induct) case 1 show ?case by simp next case 2 show ?case by (cases n) simp_all next case (3 x y xs) then have "x \<le> y" by simp show ?case proof (cases n) case 0 then show ?thesis by simp next case (Suc m) with 3 have "sorted (take m (y # xs))" by simp with Suc `x \<le> y` show ?thesis by (cases m) simp_all qed qed lemma sorted_drop: "sorted xs \<Longrightarrow> sorted (drop n xs)" proof (induct xs arbitrary: n rule: sorted.induct) case 1 show ?case by simp next case 2 show ?case by (cases n) simp_all next case 3 then show ?case by (cases n) simp_all qed lemma sorted_dropWhile: "sorted xs \<Longrightarrow> sorted (dropWhile P xs)" unfolding dropWhile_eq_drop by (rule sorted_drop) lemma sorted_takeWhile: "sorted xs \<Longrightarrow> sorted (takeWhile P xs)" apply (subst takeWhile_eq_take) by (rule sorted_take) lemma sorted_filter: "sorted (map f xs) \<Longrightarrow> sorted (map f (filter P xs))" by (induct xs) (simp_all add: sorted_Cons) lemma foldr_max_sorted: assumes "sorted (rev xs)" shows "foldr max xs y = (if xs = [] then y else max (xs ! 0) y)" using assms proof (induct xs) case (Cons x xs) moreover hence "sorted (rev xs)" using sorted_append by auto ultimately show ?case by (cases xs, auto simp add: sorted_append max_def) qed simp lemma filter_equals_takeWhile_sorted_rev: assumes sorted: "sorted (rev (map f xs))" shows "[x \<leftarrow> xs. t < f x] = takeWhile (\<lambda> x. t < f x) xs" (is "filter ?P xs = ?tW") proof (rule takeWhile_eq_filter[symmetric]) let "?dW" = "dropWhile ?P xs" fix x assume "x \<in> set ?dW" then obtain i where i: "i < length ?dW" and nth_i: "x = ?dW ! i" unfolding in_set_conv_nth by auto hence "length ?tW + i < length (?tW @ ?dW)" unfolding length_append by simp hence i': "length (map f ?tW) + i < length (map f xs)" by simp have "(map f ?tW @ map f ?dW) ! (length (map f ?tW) + i) \<le> (map f ?tW @ map f ?dW) ! (length (map f ?tW) + 0)" using sorted_rev_nth_mono[OF sorted _ i', of "length ?tW"] unfolding map_append[symmetric] by simp hence "f x \<le> f (?dW ! 0)" unfolding nth_append_length_plus nth_i using i preorder_class.le_less_trans[OF le0 i] by simp also have "... \<le> t" using hd_dropWhile[of "?P" xs] le0[THEN preorder_class.le_less_trans, OF i] using hd_conv_nth[of "?dW"] by simp finally show "\<not> t < f x" by simp qed lemma set_insort_insert: "set (insort_insert x xs) = insert x (set xs)" by (auto simp add: insort_insert_def set_insort) lemma distinct_insort_insert: assumes "distinct xs" shows "distinct (insort_insert x xs)" using assms by (induct xs) (auto simp add: insort_insert_def set_insort) lemma sorted_insort_insert: assumes "sorted xs" shows "sorted (insort_insert x xs)" using assms by (simp add: insort_insert_def sorted_insort) end lemma sorted_upt[simp]: "sorted[i..<j]" by (induct j) (simp_all add:sorted_append) lemma sorted_upto[simp]: "sorted[i..j]" apply(induct i j rule:upto.induct) apply(subst upto.simps) apply(simp add:sorted_Cons) done subsubsection {* @{const transpose} on sorted lists *} lemma sorted_transpose[simp]: shows "sorted (rev (map length (transpose xs)))" by (auto simp: sorted_equals_nth_mono rev_nth nth_transpose length_filter_conv_card intro: card_mono) lemma transpose_max_length: "foldr (\<lambda>xs. max (length xs)) (transpose xs) 0 = length [x \<leftarrow> xs. x \<noteq> []]" (is "?L = ?R") proof (cases "transpose xs = []") case False have "?L = foldr max (map length (transpose xs)) 0" by (simp add: foldr_map comp_def) also have "... = length (transpose xs ! 0)" using False sorted_transpose by (simp add: foldr_max_sorted) finally show ?thesis using False by (simp add: nth_transpose) next case True hence "[x \<leftarrow> xs. x \<noteq> []] = []" by (auto intro!: filter_False simp: transpose_empty) thus ?thesis by (simp add: transpose_empty True) qed lemma length_transpose_sorted: fixes xs :: "'a list list" assumes sorted: "sorted (rev (map length xs))" shows "length (transpose xs) = (if xs = [] then 0 else length (xs ! 0))" proof (cases "xs = []") case False thus ?thesis using foldr_max_sorted[OF sorted] False unfolding length_transpose foldr_map comp_def by simp qed simp lemma nth_nth_transpose_sorted[simp]: fixes xs :: "'a list list" assumes sorted: "sorted (rev (map length xs))" and i: "i < length (transpose xs)" and j: "j < length [ys \<leftarrow> xs. i < length ys]" shows "transpose xs ! i ! j = xs ! j ! i" using j filter_equals_takeWhile_sorted_rev[OF sorted, of i] nth_transpose[OF i] nth_map[OF j] by (simp add: takeWhile_nth) lemma transpose_column_length: fixes xs :: "'a list list" assumes sorted: "sorted (rev (map length xs))" and "i < length xs" shows "length (filter (\<lambda>ys. i < length ys) (transpose xs)) = length (xs ! i)" proof - have "xs \<noteq> []" using `i < length xs` by auto note filter_equals_takeWhile_sorted_rev[OF sorted, simp] { fix j assume "j \<le> i" note sorted_rev_nth_mono[OF sorted, of j i, simplified, OF this `i < length xs`] } note sortedE = this[consumes 1] have "{j. j < length (transpose xs) \<and> i < length (transpose xs ! j)} = {..< length (xs ! i)}" proof safe fix j assume "j < length (transpose xs)" and "i < length (transpose xs ! j)" with this(2) nth_transpose[OF this(1)] have "i < length (takeWhile (\<lambda>ys. j < length ys) xs)" by simp from nth_mem[OF this] takeWhile_nth[OF this] show "j < length (xs ! i)" by (auto dest: set_takeWhileD) next fix j assume "j < length (xs ! i)" thus "j < length (transpose xs)" using foldr_max_sorted[OF sorted] `xs \<noteq> []` sortedE[OF le0] by (auto simp: length_transpose comp_def foldr_map) have "Suc i \<le> length (takeWhile (\<lambda>ys. j < length ys) xs)" using `i < length xs` `j < length (xs ! i)` less_Suc_eq_le by (auto intro!: length_takeWhile_less_P_nth dest!: sortedE) with nth_transpose[OF `j < length (transpose xs)`] show "i < length (transpose xs ! j)" by simp qed thus ?thesis by (simp add: length_filter_conv_card) qed lemma transpose_column: fixes xs :: "'a list list" assumes sorted: "sorted (rev (map length xs))" and "i < length xs" shows "map (\<lambda>ys. ys ! i) (filter (\<lambda>ys. i < length ys) (transpose xs)) = xs ! i" (is "?R = _") proof (rule nth_equalityI, safe) show length: "length ?R = length (xs ! i)" using transpose_column_length[OF assms] by simp fix j assume j: "j < length ?R" note * = less_le_trans[OF this, unfolded length_map, OF length_filter_le] from j have j_less: "j < length (xs ! i)" using length by simp have i_less_tW: "Suc i \<le> length (takeWhile (\<lambda>ys. Suc j \<le> length ys) xs)" proof (rule length_takeWhile_less_P_nth) show "Suc i \<le> length xs" using `i < length xs` by simp fix k assume "k < Suc i" hence "k \<le> i" by auto with sorted_rev_nth_mono[OF sorted this] `i < length xs` have "length (xs ! i) \<le> length (xs ! k)" by simp thus "Suc j \<le> length (xs ! k)" using j_less by simp qed have i_less_filter: "i < length [ys\<leftarrow>xs . j < length ys]" unfolding filter_equals_takeWhile_sorted_rev[OF sorted, of j] using i_less_tW by (simp_all add: Suc_le_eq) from j show "?R ! j = xs ! i ! j" unfolding filter_equals_takeWhile_sorted_rev[OF sorted_transpose, of i] by (simp add: takeWhile_nth nth_nth_transpose_sorted[OF sorted * i_less_filter]) qed lemma transpose_transpose: fixes xs :: "'a list list" assumes sorted: "sorted (rev (map length xs))" shows "transpose (transpose xs) = takeWhile (\<lambda>x. x \<noteq> []) xs" (is "?L = ?R") proof - have len: "length ?L = length ?R" unfolding length_transpose transpose_max_length using filter_equals_takeWhile_sorted_rev[OF sorted, of 0] by simp { fix i assume "i < length ?R" with less_le_trans[OF _ length_takeWhile_le[of _ xs]] have "i < length xs" by simp } note * = this show ?thesis by (rule nth_equalityI) (simp_all add: len nth_transpose transpose_column[OF sorted] * takeWhile_nth) qed theorem transpose_rectangle: assumes "xs = [] \<Longrightarrow> n = 0" assumes rect: "\<And> i. i < length xs \<Longrightarrow> length (xs ! i) = n" shows "transpose xs = map (\<lambda> i. map (\<lambda> j. xs ! j ! i) [0..<length xs]) [0..<n]" (is "?trans = ?map") proof (rule nth_equalityI) have "sorted (rev (map length xs))" by (auto simp: rev_nth rect intro!: sorted_nth_monoI) from foldr_max_sorted[OF this] assms show len: "length ?trans = length ?map" by (simp_all add: length_transpose foldr_map comp_def) moreover { fix i assume "i < n" hence "[ys\<leftarrow>xs . i < length ys] = xs" using rect by (auto simp: in_set_conv_nth intro!: filter_True) } ultimately show "\<forall>i < length ?trans. ?trans ! i = ?map ! i" by (auto simp: nth_transpose intro: nth_equalityI) qed subsubsection {* @{text sorted_list_of_set} *} text{* This function maps (finite) linearly ordered sets to sorted lists. Warning: in most cases it is not a good idea to convert from sets to lists but one should convert in the other direction (via @{const set}). *} context linorder begin definition sorted_list_of_set :: "'a set \<Rightarrow> 'a list" where "sorted_list_of_set = Finite_Set.fold insort []" lemma sorted_list_of_set_empty [simp]: "sorted_list_of_set {} = []" by (simp add: sorted_list_of_set_def) lemma sorted_list_of_set_insert [simp]: assumes "finite A" shows "sorted_list_of_set (insert x A) = insort x (sorted_list_of_set (A - {x}))" proof - interpret fun_left_comm insort by (fact fun_left_comm_insort) with assms show ?thesis by (simp add: sorted_list_of_set_def fold_insert_remove) qed lemma sorted_list_of_set [simp]: "finite A \<Longrightarrow> set (sorted_list_of_set A) = A \<and> sorted (sorted_list_of_set A) \<and> distinct (sorted_list_of_set A)" by (induct A rule: finite_induct) (simp_all add: set_insort sorted_insort distinct_insort) lemma sorted_list_of_set_sort_remdups: "sorted_list_of_set (set xs) = sort (remdups xs)" proof - interpret fun_left_comm insort by (fact fun_left_comm_insort) show ?thesis by (simp add: sort_foldl_insort sorted_list_of_set_def fold_set_remdups) qed end subsubsection {* @{text lists}: the list-forming operator over sets *} inductive_set lists :: "'a set => 'a list set" for A :: "'a set" where Nil [intro!]: "[]: lists A" | Cons [intro!,no_atp]: "[| a: A; l: lists A|] ==> a#l : lists A" inductive_cases listsE [elim!,no_atp]: "x#l : lists A" inductive_cases listspE [elim!,no_atp]: "listsp A (x # l)" lemma listsp_mono [mono]: "A \<le> B ==> listsp A \<le> listsp B" by (rule predicate1I, erule listsp.induct, (blast dest: predicate1D)+) lemmas lists_mono = listsp_mono [to_set pred_subset_eq] lemma listsp_infI: assumes l: "listsp A l" shows "listsp B l ==> listsp (inf A B) l" using l by induct blast+ lemmas lists_IntI = listsp_infI [to_set] lemma listsp_inf_eq [simp]: "listsp (inf A B) = inf (listsp A) (listsp B)" proof (rule mono_inf [where f=listsp, THEN order_antisym]) show "mono listsp" by (simp add: mono_def listsp_mono) show "inf (listsp A) (listsp B) \<le> listsp (inf A B)" by (blast intro!: listsp_infI predicate1I) qed lemmas listsp_conj_eq [simp] = listsp_inf_eq [simplified inf_fun_eq inf_bool_eq] lemmas lists_Int_eq [simp] = listsp_inf_eq [to_set pred_equals_eq] lemma append_in_listsp_conv [iff]: "(listsp A (xs @ ys)) = (listsp A xs \<and> listsp A ys)" by (induct xs) auto lemmas append_in_lists_conv [iff] = append_in_listsp_conv [to_set] lemma in_listsp_conv_set: "(listsp A xs) = (\<forall>x \<in> set xs. A x)" -- {* eliminate @{text listsp} in favour of @{text set} *} by (induct xs) auto lemmas in_lists_conv_set = in_listsp_conv_set [to_set] lemma in_listspD [dest!,no_atp]: "listsp A xs ==> \<forall>x\<in>set xs. A x" by (rule in_listsp_conv_set [THEN iffD1]) lemmas in_listsD [dest!,no_atp] = in_listspD [to_set] lemma in_listspI [intro!,no_atp]: "\<forall>x\<in>set xs. A x ==> listsp A xs" by (rule in_listsp_conv_set [THEN iffD2]) lemmas in_listsI [intro!,no_atp] = in_listspI [to_set] lemma lists_UNIV [simp]: "lists UNIV = UNIV" by auto subsubsection {* Inductive definition for membership *} inductive ListMem :: "'a \<Rightarrow> 'a list \<Rightarrow> bool" where elem: "ListMem x (x # xs)" | insert: "ListMem x xs \<Longrightarrow> ListMem x (y # xs)" lemma ListMem_iff: "(ListMem x xs) = (x \<in> set xs)" apply (rule iffI) apply (induct set: ListMem) apply auto apply (induct xs) apply (auto intro: ListMem.intros) done subsubsection {* Lists as Cartesian products *} text{*@{text"set_Cons A Xs"}: the set of lists with head drawn from @{term A} and tail drawn from @{term Xs}.*} definition set_Cons :: "'a set \<Rightarrow> 'a list set \<Rightarrow> 'a list set" where [code del]: "set_Cons A XS = {z. \<exists>x xs. z = x # xs \<and> x \<in> A \<and> xs \<in> XS}" lemma set_Cons_sing_Nil [simp]: "set_Cons A {[]} = (%x. [x])`A" by (auto simp add: set_Cons_def) text{*Yields the set of lists, all of the same length as the argument and with elements drawn from the corresponding element of the argument.*} primrec listset :: "'a set list \<Rightarrow> 'a list set" where "listset [] = {[]}" | "listset (A # As) = set_Cons A (listset As)" subsection {* Relations on Lists *} subsubsection {* Length Lexicographic Ordering *} text{*These orderings preserve well-foundedness: shorter lists precede longer lists. These ordering are not used in dictionaries.*} primrec -- {*The lexicographic ordering for lists of the specified length*} lexn :: "('a \<times> 'a) set \<Rightarrow> nat \<Rightarrow> ('a list \<times> 'a list) set" where "lexn r 0 = {}" | "lexn r (Suc n) = (prod_fun (%(x, xs). x#xs) (%(x, xs). x#xs) ` (r <*lex*> lexn r n)) Int {(xs, ys). length xs = Suc n \<and> length ys = Suc n}" definition lex :: "('a \<times> 'a) set \<Rightarrow> ('a list \<times> 'a list) set" where [code del]: "lex r = (\<Union>n. lexn r n)" -- {*Holds only between lists of the same length*} definition lenlex :: "('a \<times> 'a) set => ('a list \<times> 'a list) set" where [code del]: "lenlex r = inv_image (less_than <*lex*> lex r) (\<lambda>xs. (length xs, xs))" -- {*Compares lists by their length and then lexicographically*} lemma wf_lexn: "wf r ==> wf (lexn r n)" apply (induct n, simp, simp) apply(rule wf_subset) prefer 2 apply (rule Int_lower1) apply(rule wf_prod_fun_image) prefer 2 apply (rule inj_onI, auto) done lemma lexn_length: "(xs, ys) : lexn r n ==> length xs = n \<and> length ys = n" by (induct n arbitrary: xs ys) auto lemma wf_lex [intro!]: "wf r ==> wf (lex r)" apply (unfold lex_def) apply (rule wf_UN) apply (blast intro: wf_lexn, clarify) apply (rename_tac m n) apply (subgoal_tac "m \<noteq> n") prefer 2 apply blast apply (blast dest: lexn_length not_sym) done lemma lexn_conv: "lexn r n = {(xs,ys). length xs = n \<and> length ys = n \<and> (\<exists>xys x y xs' ys'. xs= xys @ x#xs' \<and> ys= xys @ y # ys' \<and> (x, y):r)}" apply (induct n, simp) apply (simp add: image_Collect lex_prod_def, safe, blast) apply (rule_tac x = "ab # xys" in exI, simp) apply (case_tac xys, simp_all, blast) done lemma lex_conv: "lex r = {(xs,ys). length xs = length ys \<and> (\<exists>xys x y xs' ys'. xs = xys @ x # xs' \<and> ys = xys @ y # ys' \<and> (x, y):r)}" by (force simp add: lex_def lexn_conv) lemma wf_lenlex [intro!]: "wf r ==> wf (lenlex r)" by (unfold lenlex_def) blast lemma lenlex_conv: "lenlex r = {(xs,ys). length xs < length ys | length xs = length ys \<and> (xs, ys) : lex r}" by (simp add: lenlex_def Id_on_def lex_prod_def inv_image_def) lemma Nil_notin_lex [iff]: "([], ys) \<notin> lex r" by (simp add: lex_conv) lemma Nil2_notin_lex [iff]: "(xs, []) \<notin> lex r" by (simp add:lex_conv) lemma Cons_in_lex [simp]: "((x # xs, y # ys) : lex r) = ((x, y) : r \<and> length xs = length ys | x = y \<and> (xs, ys) : lex r)" apply (simp add: lex_conv) apply (rule iffI) prefer 2 apply (blast intro: Cons_eq_appendI, clarify) apply (case_tac xys, simp, simp) apply blast done subsubsection {* Lexicographic Ordering *} text {* Classical lexicographic ordering on lists, ie. "a" < "ab" < "b". This ordering does \emph{not} preserve well-foundedness. Author: N. Voelker, March 2005. *} definition lexord :: "('a \<times> 'a) set \<Rightarrow> ('a list \<times> 'a list) set" where [code del]: "lexord r = {(x,y ). \<exists> a v. y = x @ a # v \<or> (\<exists> u a b v w. (a,b) \<in> r \<and> x = u @ (a # v) \<and> y = u @ (b # w))}" lemma lexord_Nil_left[simp]: "([],y) \<in> lexord r = (\<exists> a x. y = a # x)" by (unfold lexord_def, induct_tac y, auto) lemma lexord_Nil_right[simp]: "(x,[]) \<notin> lexord r" by (unfold lexord_def, induct_tac x, auto) lemma lexord_cons_cons[simp]: "((a # x, b # y) \<in> lexord r) = ((a,b)\<in> r | (a = b & (x,y)\<in> lexord r))" apply (unfold lexord_def, safe, simp_all) apply (case_tac u, simp, simp) apply (case_tac u, simp, clarsimp, blast, blast, clarsimp) apply (erule_tac x="b # u" in allE) by force lemmas lexord_simps = lexord_Nil_left lexord_Nil_right lexord_cons_cons lemma lexord_append_rightI: "\<exists> b z. y = b # z \<Longrightarrow> (x, x @ y) \<in> lexord r" by (induct_tac x, auto) lemma lexord_append_left_rightI: "(a,b) \<in> r \<Longrightarrow> (u @ a # x, u @ b # y) \<in> lexord r" by (induct_tac u, auto) lemma lexord_append_leftI: " (u,v) \<in> lexord r \<Longrightarrow> (x @ u, x @ v) \<in> lexord r" by (induct x, auto) lemma lexord_append_leftD: "\<lbrakk> (x @ u, x @ v) \<in> lexord r; (! a. (a,a) \<notin> r) \<rbrakk> \<Longrightarrow> (u,v) \<in> lexord r" by (erule rev_mp, induct_tac x, auto) lemma lexord_take_index_conv: "((x,y) : lexord r) = ((length x < length y \<and> take (length x) y = x) \<or> (\<exists>i. i < min(length x)(length y) & take i x = take i y & (x!i,y!i) \<in> r))" apply (unfold lexord_def Let_def, clarsimp) apply (rule_tac f = "(% a b. a \<or> b)" in arg_cong2) apply auto apply (rule_tac x="hd (drop (length x) y)" in exI) apply (rule_tac x="tl (drop (length x) y)" in exI) apply (erule subst, simp add: min_def) apply (rule_tac x ="length u" in exI, simp) apply (rule_tac x ="take i x" in exI) apply (rule_tac x ="x ! i" in exI) apply (rule_tac x ="y ! i" in exI, safe) apply (rule_tac x="drop (Suc i) x" in exI) apply (drule sym, simp add: drop_Suc_conv_tl) apply (rule_tac x="drop (Suc i) y" in exI) by (simp add: drop_Suc_conv_tl) -- {* lexord is extension of partial ordering List.lex *} lemma lexord_lex: " (x,y) \<in> lex r = ((x,y) \<in> lexord r \<and> length x = length y)" apply (rule_tac x = y in spec) apply (induct_tac x, clarsimp) by (clarify, case_tac x, simp, force) lemma lexord_irreflexive: "(! x. (x,x) \<notin> r) \<Longrightarrow> (y,y) \<notin> lexord r" by (induct y, auto) lemma lexord_trans: "\<lbrakk> (x, y) \<in> lexord r; (y, z) \<in> lexord r; trans r \<rbrakk> \<Longrightarrow> (x, z) \<in> lexord r" apply (erule rev_mp)+ apply (rule_tac x = x in spec) apply (rule_tac x = z in spec) apply ( induct_tac y, simp, clarify) apply (case_tac xa, erule ssubst) apply (erule allE, erule allE) -- {* avoid simp recursion *} apply (case_tac x, simp, simp) apply (case_tac x, erule allE, erule allE, simp) apply (erule_tac x = listb in allE) apply (erule_tac x = lista in allE, simp) apply (unfold trans_def) by blast lemma lexord_transI: "trans r \<Longrightarrow> trans (lexord r)" by (rule transI, drule lexord_trans, blast) lemma lexord_linear: "(! a b. (a,b)\<in> r | a = b | (b,a) \<in> r) \<Longrightarrow> (x,y) : lexord r | x = y | (y,x) : lexord r" apply (rule_tac x = y in spec) apply (induct_tac x, rule allI) apply (case_tac x, simp, simp) apply (rule allI, case_tac x, simp, simp) by blast subsection {* Lexicographic combination of measure functions *} text {* These are useful for termination proofs *} definition "measures fs = inv_image (lex less_than) (%a. map (%f. f a) fs)" lemma wf_measures[recdef_wf, simp]: "wf (measures fs)" unfolding measures_def by blast lemma in_measures[simp]: "(x, y) \<in> measures [] = False" "(x, y) \<in> measures (f # fs) = (f x < f y \<or> (f x = f y \<and> (x, y) \<in> measures fs))" unfolding measures_def by auto lemma measures_less: "f x < f y ==> (x, y) \<in> measures (f#fs)" by simp lemma measures_lesseq: "f x <= f y ==> (x, y) \<in> measures fs ==> (x, y) \<in> measures (f#fs)" by auto subsubsection {* Lifting a Relation on List Elements to the Lists *} inductive_set listrel :: "('a * 'a)set => ('a list * 'a list)set" for r :: "('a * 'a)set" where Nil: "([],[]) \<in> listrel r" | Cons: "[| (x,y) \<in> r; (xs,ys) \<in> listrel r |] ==> (x#xs, y#ys) \<in> listrel r" inductive_cases listrel_Nil1 [elim!]: "([],xs) \<in> listrel r" inductive_cases listrel_Nil2 [elim!]: "(xs,[]) \<in> listrel r" inductive_cases listrel_Cons1 [elim!]: "(y#ys,xs) \<in> listrel r" inductive_cases listrel_Cons2 [elim!]: "(xs,y#ys) \<in> listrel r" lemma listrel_mono: "r \<subseteq> s \<Longrightarrow> listrel r \<subseteq> listrel s" apply clarify apply (erule listrel.induct) apply (blast intro: listrel.intros)+ done lemma listrel_subset: "r \<subseteq> A \<times> A \<Longrightarrow> listrel r \<subseteq> lists A \<times> lists A" apply clarify apply (erule listrel.induct, auto) done lemma listrel_refl_on: "refl_on A r \<Longrightarrow> refl_on (lists A) (listrel r)" apply (simp add: refl_on_def listrel_subset Ball_def) apply (rule allI) apply (induct_tac x) apply (auto intro: listrel.intros) done lemma listrel_sym: "sym r \<Longrightarrow> sym (listrel r)" apply (auto simp add: sym_def) apply (erule listrel.induct) apply (blast intro: listrel.intros)+ done lemma listrel_trans: "trans r \<Longrightarrow> trans (listrel r)" apply (simp add: trans_def) apply (intro allI) apply (rule impI) apply (erule listrel.induct) apply (blast intro: listrel.intros)+ done theorem equiv_listrel: "equiv A r \<Longrightarrow> equiv (lists A) (listrel r)" by (simp add: equiv_def listrel_refl_on listrel_sym listrel_trans) lemma listrel_Nil [simp]: "listrel r `` {[]} = {[]}" by (blast intro: listrel.intros) lemma listrel_Cons: "listrel r `` {x#xs} = set_Cons (r``{x}) (listrel r `` {xs})" by (auto simp add: set_Cons_def intro: listrel.intros) subsection {* Size function *} lemma [measure_function]: "is_measure f \<Longrightarrow> is_measure (list_size f)" by (rule is_measure_trivial) lemma [measure_function]: "is_measure f \<Longrightarrow> is_measure (option_size f)" by (rule is_measure_trivial) lemma list_size_estimation[termination_simp]: "x \<in> set xs \<Longrightarrow> y < f x \<Longrightarrow> y < list_size f xs" by (induct xs) auto lemma list_size_estimation'[termination_simp]: "x \<in> set xs \<Longrightarrow> y \<le> f x \<Longrightarrow> y \<le> list_size f xs" by (induct xs) auto lemma list_size_map[simp]: "list_size f (map g xs) = list_size (f o g) xs" by (induct xs) auto lemma list_size_pointwise[termination_simp]: "(\<And>x. x \<in> set xs \<Longrightarrow> f x < g x) \<Longrightarrow> list_size f xs \<le> list_size g xs" by (induct xs) force+ subsection {* Transfer *} definition embed_list :: "nat list \<Rightarrow> int list" where "embed_list l = map int l" definition nat_list :: "int list \<Rightarrow> bool" where "nat_list l = nat_set (set l)" definition return_list :: "int list \<Rightarrow> nat list" where "return_list l = map nat l" lemma transfer_nat_int_list_return_embed: "nat_list l \<longrightarrow> embed_list (return_list l) = l" unfolding embed_list_def return_list_def nat_list_def nat_set_def apply (induct l) apply auto done lemma transfer_nat_int_list_functions: "l @ m = return_list (embed_list l @ embed_list m)" "[] = return_list []" unfolding return_list_def embed_list_def apply auto apply (induct l, auto) apply (induct m, auto) done (* lemma transfer_nat_int_fold1: "fold f l x = fold (%x. f (nat x)) (embed_list l) x"; *) subsection {* Code generator *} subsubsection {* Setup *} use "Tools/list_code.ML" code_type list (SML "_ list") (OCaml "_ list") (Haskell "![(_)]") (Scala "List[(_)]") code_const Nil (SML "[]") (OCaml "[]") (Haskell "[]") (Scala "Nil") code_instance list :: eq (Haskell -) code_const "eq_class.eq \<Colon> 'a\<Colon>eq list \<Rightarrow> 'a list \<Rightarrow> bool" (Haskell infixl 4 "==") code_reserved SML list code_reserved OCaml list types_code "list" ("_ list") attach (term_of) {* fun term_of_list f T = HOLogic.mk_list T o map f; *} attach (test) {* fun gen_list' aG aT i j = frequency [(i, fn () => let val (x, t) = aG j; val (xs, ts) = gen_list' aG aT (i-1) j in (x :: xs, fn () => HOLogic.cons_const aT $ t () $ ts ()) end), (1, fn () => ([], fn () => HOLogic.nil_const aT))] () and gen_list aG aT i = gen_list' aG aT i i; *} consts_code Cons ("(_ ::/ _)") setup {* let fun list_codegen thy defs dep thyname b t gr = let val ts = HOLogic.dest_list t; val (_, gr') = Codegen.invoke_tycodegen thy defs dep thyname false (fastype_of t) gr; val (ps, gr'') = fold_map (Codegen.invoke_codegen thy defs dep thyname false) ts gr' in SOME (Pretty.list "[" "]" ps, gr'') end handle TERM _ => NONE; in fold (List_Code.add_literal_list) ["SML", "OCaml", "Haskell", "Scala"] #> Codegen.add_codegen "list_codegen" list_codegen end *} subsubsection {* Generation of efficient code *} primrec member :: "'a \<Rightarrow> 'a list \<Rightarrow> bool" (infixl "mem" 55) where "x mem [] \<longleftrightarrow> False" | "x mem (y#ys) \<longleftrightarrow> x = y \<or> x mem ys" primrec null:: "'a list \<Rightarrow> bool" where "null [] = True" | "null (x#xs) = False" primrec list_inter :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" where "list_inter [] bs = []" | "list_inter (a#as) bs = (if a \<in> set bs then a # list_inter as bs else list_inter as bs)" primrec list_all :: "('a \<Rightarrow> bool) \<Rightarrow> ('a list \<Rightarrow> bool)" where "list_all P [] = True" | "list_all P (x#xs) = (P x \<and> list_all P xs)" primrec list_ex :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> bool" where "list_ex P [] = False" | "list_ex P (x#xs) = (P x \<or> list_ex P xs)" primrec filtermap :: "('a \<Rightarrow> 'b option) \<Rightarrow> 'a list \<Rightarrow> 'b list" where "filtermap f [] = []" | "filtermap f (x#xs) = (case f x of None \<Rightarrow> filtermap f xs | Some y \<Rightarrow> y # filtermap f xs)" primrec map_filter :: "('a \<Rightarrow> 'b) \<Rightarrow> ('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'b list" where "map_filter f P [] = []" | "map_filter f P (x#xs) = (if P x then f x # map_filter f P xs else map_filter f P xs)" primrec length_unique :: "'a list \<Rightarrow> nat" where "length_unique [] = 0" | "length_unique (x#xs) = (if x \<in> set xs then length_unique xs else Suc (length_unique xs))" primrec concat_map :: "('a => 'b list) => 'a list => 'b list" where "concat_map f [] = []" | "concat_map f (x#xs) = f x @ concat_map f xs" text {* Only use @{text mem} for generating executable code. Otherwise use @{prop "x : set xs"} instead --- it is much easier to reason about. The same is true for @{const list_all} and @{const list_ex}: write @{text "\<forall>x\<in>set xs"} and @{text "\<exists>x\<in>set xs"} instead because the HOL quantifiers are aleady known to the automatic provers. In fact, the declarations in the code subsection make sure that @{text "\<in>"}, @{text "\<forall>x\<in>set xs"} and @{text "\<exists>x\<in>set xs"} are implemented efficiently. Efficient emptyness check is implemented by @{const null}. The functions @{const filtermap} and @{const map_filter} are just there to generate efficient code. Do not use them for modelling and proving. *} lemma rev_foldl_cons [code]: "rev xs = foldl (\<lambda>xs x. x # xs) [] xs" proof (induct xs) case Nil then show ?case by simp next case Cons { fix x xs ys have "foldl (\<lambda>xs x. x # xs) ys xs @ [x] = foldl (\<lambda>xs x. x # xs) (ys @ [x]) xs" by (induct xs arbitrary: ys) auto } note aux = this show ?case by (induct xs) (auto simp add: Cons aux) qed lemma mem_iff [code_post]: "x mem xs \<longleftrightarrow> x \<in> set xs" by (induct xs) auto lemmas in_set_code [code_unfold] = mem_iff [symmetric] lemma empty_null: "xs = [] \<longleftrightarrow> null xs" by (cases xs) simp_all lemma [code_unfold]: "eq_class.eq xs [] \<longleftrightarrow> null xs" by (simp add: eq empty_null) lemmas null_empty [code_post] = empty_null [symmetric] lemma list_inter_conv: "set (list_inter xs ys) = set xs \<inter> set ys" by (induct xs) auto lemma list_all_iff [code_post]: "list_all P xs \<longleftrightarrow> (\<forall>x \<in> set xs. P x)" by (induct xs) auto lemmas list_ball_code [code_unfold] = list_all_iff [symmetric] lemma list_all_append [simp]: "list_all P (xs @ ys) \<longleftrightarrow> (list_all P xs \<and> list_all P ys)" by (induct xs) auto lemma list_all_rev [simp]: "list_all P (rev xs) \<longleftrightarrow> list_all P xs" by (simp add: list_all_iff) lemma list_all_length: "list_all P xs \<longleftrightarrow> (\<forall>n < length xs. P (xs ! n))" unfolding list_all_iff by (auto intro: all_nth_imp_all_set) lemma list_ex_iff [code_post]: "list_ex P xs \<longleftrightarrow> (\<exists>x \<in> set xs. P x)" by (induct xs) simp_all lemmas list_bex_code [code_unfold] = list_ex_iff [symmetric] lemma list_ex_length: "list_ex P xs \<longleftrightarrow> (\<exists>n < length xs. P (xs ! n))" unfolding list_ex_iff set_conv_nth by auto lemma filtermap_conv: "filtermap f xs = map (\<lambda>x. the (f x)) (filter (\<lambda>x. f x \<noteq> None) xs)" by (induct xs) (simp_all split: option.split) lemma map_filter_conv [simp]: "map_filter f P xs = map f (filter P xs)" by (induct xs) auto lemma length_remdups_length_unique [code_unfold]: "length (remdups xs) = length_unique xs" by (induct xs) simp_all lemma concat_map_code[code_unfold]: "concat(map f xs) = concat_map f xs" by (induct xs) simp_all declare INFI_def [code_unfold] declare SUPR_def [code_unfold] declare set_map [symmetric, code_unfold] hide_const (open) length_unique text {* Code for bounded quantification and summation over nats. *} lemma atMost_upto [code_unfold]: "{..n} = set [0..<Suc n]" by auto lemma atLeast_upt [code_unfold]: "{..<n} = set [0..<n]" by auto lemma greaterThanLessThan_upt [code_unfold]: "{n<..<m} = set [Suc n..<m]" by auto lemmas atLeastLessThan_upt [code_unfold] = set_upt [symmetric] lemma greaterThanAtMost_upt [code_unfold]: "{n<..m} = set [Suc n..<Suc m]" by auto lemma atLeastAtMost_upt [code_unfold]: "{n..m} = set [n..<Suc m]" by auto lemma all_nat_less_eq [code_unfold]: "(\<forall>m<n\<Colon>nat. P m) \<longleftrightarrow> (\<forall>m \<in> {0..<n}. P m)" by auto lemma ex_nat_less_eq [code_unfold]: "(\<exists>m<n\<Colon>nat. P m) \<longleftrightarrow> (\<exists>m \<in> {0..<n}. P m)" by auto lemma all_nat_less [code_unfold]: "(\<forall>m\<le>n\<Colon>nat. P m) \<longleftrightarrow> (\<forall>m \<in> {0..n}. P m)" by auto lemma ex_nat_less [code_unfold]: "(\<exists>m\<le>n\<Colon>nat. P m) \<longleftrightarrow> (\<exists>m \<in> {0..n}. P m)" by auto lemma setsum_set_distinct_conv_listsum: "distinct xs \<Longrightarrow> setsum f (set xs) = listsum (map f xs)" by (induct xs) simp_all lemma setsum_set_upt_conv_listsum [code_unfold]: "setsum f (set [m..<n]) = listsum (map f [m..<n])" by (rule setsum_set_distinct_conv_listsum) simp text {* General equivalence between @{const listsum} and @{const setsum} *} lemma listsum_setsum_nth: "listsum xs = (\<Sum> i = 0 ..< length xs. xs ! i)" using setsum_set_upt_conv_listsum[of "op ! xs" 0 "length xs"] by (simp add: map_nth) text {* Code for summation over ints. *} lemma greaterThanLessThan_upto [code_unfold]: "{i<..<j::int} = set [i+1..j - 1]" by auto lemma atLeastLessThan_upto [code_unfold]: "{i..<j::int} = set [i..j - 1]" by auto lemma greaterThanAtMost_upto [code_unfold]: "{i<..j::int} = set [i+1..j]" by auto lemmas atLeastAtMost_upto [code_unfold] = set_upto[symmetric] lemma setsum_set_upto_conv_listsum [code_unfold]: "setsum f (set [i..j::int]) = listsum (map f [i..j])" by (rule setsum_set_distinct_conv_listsum) simp text {* Optimized code for @{text"\<forall>i\<in>{a..b::int}"} and @{text"\<forall>n:{a..<b::nat}"} and similiarly for @{text"\<exists>"}. *} function all_from_to_nat :: "(nat \<Rightarrow> bool) \<Rightarrow> nat \<Rightarrow> nat \<Rightarrow> bool" where "all_from_to_nat P i j = (if i < j then if P i then all_from_to_nat P (i+1) j else False else True)" by auto termination by (relation "measure(%(P,i,j). j - i)") auto declare all_from_to_nat.simps[simp del] lemma all_from_to_nat_iff_ball: "all_from_to_nat P i j = (ALL n : {i ..< j}. P n)" proof(induct P i j rule:all_from_to_nat.induct) case (1 P i j) let ?yes = "i < j & P i" show ?case proof (cases) assume ?yes hence "all_from_to_nat P i j = (P i & all_from_to_nat P (i+1) j)" by(simp add: all_from_to_nat.simps) also have "... = (P i & (ALL n : {i+1 ..< j}. P n))" using `?yes` 1 by simp also have "... = (ALL n : {i ..< j}. P n)" (is "?L = ?R") proof assume L: ?L show ?R proof clarify fix n assume n: "n : {i..<j}" show "P n" proof cases assume "n = i" thus "P n" using L by simp next assume "n ~= i" hence "i+1 <= n" using n by auto thus "P n" using L n by simp qed qed next assume R: ?R thus ?L using `?yes` 1 by auto qed finally show ?thesis . next assume "~?yes" thus ?thesis by(auto simp add: all_from_to_nat.simps) qed qed lemma list_all_iff_all_from_to_nat[code_unfold]: "list_all P [i..<j] = all_from_to_nat P i j" by(simp add: all_from_to_nat_iff_ball list_all_iff) lemma list_ex_iff_not_all_from_to_not_nat[code_unfold]: "list_ex P [i..<j] = (~all_from_to_nat (%x. ~P x) i j)" by(simp add: all_from_to_nat_iff_ball list_ex_iff) function all_from_to_int :: "(int \<Rightarrow> bool) \<Rightarrow> int \<Rightarrow> int \<Rightarrow> bool" where "all_from_to_int P i j = (if i <= j then if P i then all_from_to_int P (i+1) j else False else True)" by auto termination by (relation "measure(%(P,i,j). nat(j - i + 1))") auto declare all_from_to_int.simps[simp del] lemma all_from_to_int_iff_ball: "all_from_to_int P i j = (ALL n : {i .. j}. P n)" proof(induct P i j rule:all_from_to_int.induct) case (1 P i j) let ?yes = "i <= j & P i" show ?case proof (cases) assume ?yes hence "all_from_to_int P i j = (P i & all_from_to_int P (i+1) j)" by(simp add: all_from_to_int.simps) also have "... = (P i & (ALL n : {i+1 .. j}. P n))" using `?yes` 1 by simp also have "... = (ALL n : {i .. j}. P n)" (is "?L = ?R") proof assume L: ?L show ?R proof clarify fix n assume n: "n : {i..j}" show "P n" proof cases assume "n = i" thus "P n" using L by simp next assume "n ~= i" hence "i+1 <= n" using n by auto thus "P n" using L n by simp qed qed next assume R: ?R thus ?L using `?yes` 1 by auto qed finally show ?thesis . next assume "~?yes" thus ?thesis by(auto simp add: all_from_to_int.simps) qed qed lemma list_all_iff_all_from_to_int[code_unfold]: "list_all P [i..j] = all_from_to_int P i j" by(simp add: all_from_to_int_iff_ball list_all_iff) lemma list_ex_iff_not_all_from_to_not_int[code_unfold]: "list_ex P [i..j] = (~ all_from_to_int (%x. ~P x) i j)" by(simp add: all_from_to_int_iff_ball list_ex_iff) end