Prod.ML: Added split_paired_EX and lots of comments about failed attempts to
automate reasoning about products.
simpdata.ML: added simplification procedure for simplifying existential
statements of the form ? x. ... & x = t & ...
(* Title: HOL/prod
ID: $Id$
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1991 University of Cambridge
For prod.thy. Ordered Pairs, the Cartesian product type, the unit type
*)
open Prod;
(*This counts as a non-emptiness result for admitting 'a * 'b as a type*)
goalw Prod.thy [Prod_def] "Pair_Rep a b : Prod";
by (EVERY1 [rtac CollectI, rtac exI, rtac exI, rtac refl]);
qed "ProdI";
val [major] = goalw Prod.thy [Pair_Rep_def]
"Pair_Rep a b = Pair_Rep a' b' ==> a=a' & b=b'";
by (EVERY1 [rtac (major RS fun_cong RS fun_cong RS subst),
rtac conjI, rtac refl, rtac refl]);
qed "Pair_Rep_inject";
goal Prod.thy "inj_onto Abs_Prod Prod";
by (rtac inj_onto_inverseI 1);
by (etac Abs_Prod_inverse 1);
qed "inj_onto_Abs_Prod";
val prems = goalw Prod.thy [Pair_def]
"[| (a, b) = (a',b'); [| a=a'; b=b' |] ==> R |] ==> R";
by (rtac (inj_onto_Abs_Prod RS inj_ontoD RS Pair_Rep_inject RS conjE) 1);
by (REPEAT (ares_tac (prems@[ProdI]) 1));
qed "Pair_inject";
goal Prod.thy "((a,b) = (a',b')) = (a=a' & b=b')";
by (blast_tac (!claset addSEs [Pair_inject]) 1);
qed "Pair_eq";
AddIffs [Pair_eq];
goalw Prod.thy [fst_def] "fst((a,b)) = a";
by (blast_tac (!claset addIs [select_equality]) 1);
qed "fst_conv";
goalw Prod.thy [snd_def] "snd((a,b)) = b";
by (blast_tac (!claset addIs [select_equality]) 1);
qed "snd_conv";
goalw Prod.thy [Pair_def] "? x y. p = (x,y)";
by (rtac (rewrite_rule [Prod_def] Rep_Prod RS CollectE) 1);
by (EVERY1[etac exE, etac exE, rtac exI, rtac exI,
rtac (Rep_Prod_inverse RS sym RS trans), etac arg_cong]);
qed "PairE_lemma";
val [prem] = goal Prod.thy "[| !!x y. p = (x,y) ==> Q |] ==> Q";
by (rtac (PairE_lemma RS exE) 1);
by (REPEAT (eresolve_tac [prem,exE] 1));
qed "PairE";
(* replace parameters of product type by individual component parameters *)
local
fun is_pair (_,Type("*",_)) = true
| is_pair _ = false;
fun find_pair_param prem =
let val params = Logic.strip_params prem
in if exists is_pair params
then let val params = rev(rename_wrt_term prem params)
(*as they are printed*)
in apsome fst (find_first is_pair params) end
else None
end;
in
val split_all_tac = REPEAT o SUBGOAL (fn (prem,i) =>
case find_pair_param prem of
None => no_tac
| Some x => EVERY[res_inst_tac[("p",x)] PairE i,
REPEAT(hyp_subst_tac i), prune_params_tac]);
end;
(* Could be nice, but breaks too many proofs:
claset := !claset addbefore split_all_tac;
*)
(*** lemmas for splitting paired `!!'
Does not work with simplifier because it also affects premises in
congrence rules, where is can lead to premises of the form
!!a b. ... = ?P(a,b)
which cannot be solved by reflexivity.
val [prem] = goal Prod.thy "(!!x.PROP P x) ==> (!!a b. PROP P(a,b))";
br prem 1;
val lemma1 = result();
local
val psig = sign_of Prod.thy;
val pT = Sign.read_typ (psig, K None) "?'a*?'b=>prop";
val PeqP = reflexive(read_cterm psig ("P", pT));
val psplit = zero_var_indexes(read_instantiate [("p","x")]
surjective_pairing RS eq_reflection)
in
val adhoc = combination PeqP psplit
end;
val [prem] = goal Prod.thy "(!!a b. PROP P(a,b)) ==> PROP P x";
bw adhoc;
br prem 1;
val lemma = result();
val [prem] = goal Prod.thy "(!!a b. PROP P(a,b)) ==> (!!x. PROP P x)";
br lemma 1;
br prem 1;
val lemma2 = result();
bind_thm("split_paired_all", equal_intr lemma1 lemma2);
Addsimps [split_paired_all];
***)
goal Prod.thy "(!x. P x) = (!a b. P(a,b))";
by (fast_tac (!claset addbefore split_all_tac) 1);
qed "split_paired_All";
Addsimps [split_paired_All];
(* AddIffs is not a good idea because it makes Blast_tac loop *)
goal Prod.thy "(? x. P x) = (? a b. P(a,b))";
by (fast_tac (!claset addbefore split_all_tac) 1);
qed "split_paired_Ex";
(* Addsimps [split_paired_Ex]; breaks a number of IOA proofs *)
goalw Prod.thy [split_def] "split c (a,b) = c a b";
by (EVERY1[stac fst_conv, stac snd_conv]);
by (rtac refl 1);
qed "split";
Addsimps [fst_conv, snd_conv, split];
goal Prod.thy "(s=t) = (fst(s)=fst(t) & snd(s)=snd(t))";
by (res_inst_tac[("p","s")] PairE 1);
by (res_inst_tac[("p","t")] PairE 1);
by (Asm_simp_tac 1);
qed "Pair_fst_snd_eq";
(*Prevents simplification of c: much faster*)
qed_goal "split_weak_cong" Prod.thy
"p=q ==> split c p = split c q"
(fn [prem] => [rtac (prem RS arg_cong) 1]);
(* Do not add as rewrite rule: invalidates some proofs in IMP *)
goal Prod.thy "p = (fst(p),snd(p))";
by (res_inst_tac [("p","p")] PairE 1);
by (Asm_simp_tac 1);
qed "surjective_pairing";
goal Prod.thy "p = split (%x y.(x,y)) p";
by (res_inst_tac [("p","p")] PairE 1);
by (Asm_simp_tac 1);
qed "surjective_pairing2";
qed_goal "split_eta" Prod.thy "(%(x,y). f(x,y)) = f"
(fn _ => [rtac ext 1, split_all_tac 1, rtac split 1]);
(*For use with split_tac and the simplifier*)
goal Prod.thy "R(split c p) = (! x y. p = (x,y) --> R(c x y))";
by (stac surjective_pairing 1);
by (stac split 1);
by (Blast_tac 1);
qed "expand_split";
(* could be done after split_tac has been speeded up significantly:
simpset := (!simpset setloop split_tac[expand_split]);
precompute the constants involved and don't do anything unless
the current goal contains one of those constants
*)
(** split used as a logical connective or set former **)
(*These rules are for use with blast_tac.
Could instead call simp_tac/asm_full_simp_tac using split as rewrite.*)
goal Prod.thy "!!p. [| !!a b. p=(a,b) ==> c a b |] ==> split c p";
by (split_all_tac 1);
by (Asm_simp_tac 1);
qed "splitI2";
goal Prod.thy "!!a b c. c a b ==> split c (a,b)";
by (Asm_simp_tac 1);
qed "splitI";
val prems = goalw Prod.thy [split_def]
"[| split c p; !!x y. [| p = (x,y); c x y |] ==> Q |] ==> Q";
by (REPEAT (resolve_tac (prems@[surjective_pairing]) 1));
qed "splitE";
goal Prod.thy "!!R a b. split R (a,b) ==> R a b";
by (etac (split RS iffD1) 1);
qed "splitD";
goal Prod.thy "!!a b c. z: c a b ==> z: split c (a,b)";
by (Asm_simp_tac 1);
qed "mem_splitI";
goal Prod.thy "!!p. [| !!a b. p=(a,b) ==> z: c a b |] ==> z: split c p";
by (split_all_tac 1);
by (Asm_simp_tac 1);
qed "mem_splitI2";
val prems = goalw Prod.thy [split_def]
"[| z: split c p; !!x y. [| p = (x,y); z: c x y |] ==> Q |] ==> Q";
by (REPEAT (resolve_tac (prems@[surjective_pairing]) 1));
qed "mem_splitE";
AddSIs [splitI, splitI2, mem_splitI, mem_splitI2];
AddSEs [splitE, mem_splitE];
(*** prod_fun -- action of the product functor upon functions ***)
goalw Prod.thy [prod_fun_def] "prod_fun f g (a,b) = (f(a),g(b))";
by (rtac split 1);
qed "prod_fun";
goal Prod.thy
"prod_fun (f1 o f2) (g1 o g2) = ((prod_fun f1 g1) o (prod_fun f2 g2))";
by (rtac ext 1);
by (res_inst_tac [("p","x")] PairE 1);
by (asm_simp_tac (!simpset addsimps [prod_fun,o_def]) 1);
qed "prod_fun_compose";
goal Prod.thy "prod_fun (%x.x) (%y.y) = (%z.z)";
by (rtac ext 1);
by (res_inst_tac [("p","z")] PairE 1);
by (asm_simp_tac (!simpset addsimps [prod_fun]) 1);
qed "prod_fun_ident";
val prems = goal Prod.thy "(a,b):r ==> (f(a),g(b)) : (prod_fun f g)``r";
by (rtac image_eqI 1);
by (rtac (prod_fun RS sym) 1);
by (resolve_tac prems 1);
qed "prod_fun_imageI";
val major::prems = goal Prod.thy
"[| c: (prod_fun f g)``r; !!x y. [| c=(f(x),g(y)); (x,y):r |] ==> P \
\ |] ==> P";
by (rtac (major RS imageE) 1);
by (res_inst_tac [("p","x")] PairE 1);
by (resolve_tac prems 1);
by (Blast_tac 2);
by (blast_tac (!claset addIs [prod_fun]) 1);
qed "prod_fun_imageE";
(*** Disjoint union of a family of sets - Sigma ***)
qed_goalw "SigmaI" Prod.thy [Sigma_def]
"[| a:A; b:B(a) |] ==> (a,b) : Sigma A B"
(fn prems=> [ (REPEAT (resolve_tac (prems@[singletonI,UN_I]) 1)) ]);
AddSIs [SigmaI];
(*The general elimination rule*)
qed_goalw "SigmaE" Prod.thy [Sigma_def]
"[| c: Sigma A B; \
\ !!x y.[| x:A; y:B(x); c=(x,y) |] ==> P \
\ |] ==> P"
(fn major::prems=>
[ (cut_facts_tac [major] 1),
(REPEAT (eresolve_tac [UN_E, singletonE] 1 ORELSE ares_tac prems 1)) ]);
(** Elimination of (a,b):A*B -- introduces no eigenvariables **)
qed_goal "SigmaD1" Prod.thy "(a,b) : Sigma A B ==> a : A"
(fn [major]=>
[ (rtac (major RS SigmaE) 1),
(REPEAT (eresolve_tac [asm_rl,Pair_inject,ssubst] 1)) ]);
qed_goal "SigmaD2" Prod.thy "(a,b) : Sigma A B ==> b : B(a)"
(fn [major]=>
[ (rtac (major RS SigmaE) 1),
(REPEAT (eresolve_tac [asm_rl,Pair_inject,ssubst] 1)) ]);
qed_goal "SigmaE2" Prod.thy
"[| (a,b) : Sigma A B; \
\ [| a:A; b:B(a) |] ==> P \
\ |] ==> P"
(fn [major,minor]=>
[ (rtac minor 1),
(rtac (major RS SigmaD1) 1),
(rtac (major RS SigmaD2) 1) ]);
AddSEs [SigmaE2, SigmaE];
val prems = goal Prod.thy
"[| A<=C; !!x. x:A ==> B x <= D x |] ==> Sigma A B <= Sigma C D";
by (cut_facts_tac prems 1);
by (blast_tac (!claset addIs (prems RL [subsetD])) 1);
qed "Sigma_mono";
qed_goal "Sigma_empty1" Prod.thy "Sigma {} B = {}"
(fn _ => [ (Blast_tac 1) ]);
qed_goal "Sigma_empty2" Prod.thy "A Times {} = {}"
(fn _ => [ (Blast_tac 1) ]);
Addsimps [Sigma_empty1,Sigma_empty2];
goal Prod.thy "((a,b): Sigma A B) = (a:A & b:B(a))";
by (Blast_tac 1);
qed "mem_Sigma_iff";
AddIffs [mem_Sigma_iff];
(*Suggested by Pierre Chartier*)
goal Prod.thy
"(UN (a,b):(A Times B). E a Times F b) = (UNION A E) Times (UNION B F)";
by (Blast_tac 1);
qed "UNION_Times_distrib";
(*** Domain of a relation ***)
val prems = goalw Prod.thy [image_def] "(a,b) : r ==> a : fst``r";
by (rtac CollectI 1);
by (rtac bexI 1);
by (rtac (fst_conv RS sym) 1);
by (resolve_tac prems 1);
qed "fst_imageI";
val major::prems = goal Prod.thy
"[| a : fst``r; !!y.[| (a,y) : r |] ==> P |] ==> P";
by (rtac (major RS imageE) 1);
by (resolve_tac prems 1);
by (etac ssubst 1);
by (rtac (surjective_pairing RS subst) 1);
by (assume_tac 1);
qed "fst_imageE";
(*** Range of a relation ***)
val prems = goalw Prod.thy [image_def] "(a,b) : r ==> b : snd``r";
by (rtac CollectI 1);
by (rtac bexI 1);
by (rtac (snd_conv RS sym) 1);
by (resolve_tac prems 1);
qed "snd_imageI";
val major::prems = goal Prod.thy
"[| a : snd``r; !!y.[| (y,a) : r |] ==> P |] ==> P";
by (rtac (major RS imageE) 1);
by (resolve_tac prems 1);
by (etac ssubst 1);
by (rtac (surjective_pairing RS subst) 1);
by (assume_tac 1);
qed "snd_imageE";
(** Exhaustion rule for unit -- a degenerate form of induction **)
goalw Prod.thy [Unity_def]
"u = ()";
by (stac (rewrite_rule [unit_def] Rep_unit RS singletonD RS sym) 1);
by (rtac (Rep_unit_inverse RS sym) 1);
qed "unit_eq";
AddIs [fst_imageI, snd_imageI, prod_fun_imageI];
AddSEs [fst_imageE, snd_imageE, prod_fun_imageE];
structure Prod_Syntax =
struct
val unitT = Type("unit",[]);
fun mk_prod (T1,T2) = Type("*", [T1,T2]);
(*Maps the type T1*...*Tn to [T1,...,Tn], however nested*)
fun factors (Type("*", [T1,T2])) = factors T1 @ factors T2
| factors T = [T];
(*Make a correctly typed ordered pair*)
fun mk_Pair (t1,t2) =
let val T1 = fastype_of t1
and T2 = fastype_of t2
in Const("Pair", [T1, T2] ---> mk_prod(T1,T2)) $ t1 $ t2 end;
fun split_const(Ta,Tb,Tc) =
Const("split", [[Ta,Tb]--->Tc, mk_prod(Ta,Tb)] ---> Tc);
(*In ap_split S T u, term u expects separate arguments for the factors of S,
with result type T. The call creates a new term expecting one argument
of type S.*)
fun ap_split (Type("*", [T1,T2])) T3 u =
split_const(T1,T2,T3) $
Abs("v", T1,
ap_split T2 T3
((ap_split T1 (factors T2 ---> T3) (incr_boundvars 1 u)) $
Bound 0))
| ap_split T T3 u = u;
(*Makes a nested tuple from a list, following the product type structure*)
fun mk_tuple (Type("*", [T1,T2])) tms =
mk_Pair (mk_tuple T1 tms,
mk_tuple T2 (drop (length (factors T1), tms)))
| mk_tuple T (t::_) = t;
(*Attempts to remove occurrences of split, and pair-valued parameters*)
val remove_split = rewrite_rule [split RS eq_reflection] o
rule_by_tactic (ALLGOALS split_all_tac);
(*Uncurries any Var of function type in the rule*)
fun split_rule_var (t as Var(v, Type("fun",[T1,T2])), rl) =
let val T' = factors T1 ---> T2
val newt = ap_split T1 T2 (Var(v,T'))
val cterm = Thm.cterm_of (#sign(rep_thm rl))
in
remove_split (instantiate ([], [(cterm t, cterm newt)]) rl)
end
| split_rule_var (t,rl) = rl;
(*Uncurries ALL function variables occurring in a rule's conclusion*)
fun split_rule rl = foldr split_rule_var (term_vars (concl_of rl), rl)
|> standard;
end;