src/HOL/NatBin.thy
author wenzelm
Fri Mar 28 19:43:54 2008 +0100 (2008-03-28)
changeset 26462 dac4e2bce00d
parent 26342 0f65fa163304
child 27651 16a26996c30e
permissions -rw-r--r--
avoid rebinding of existing facts;
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(*  Title:      HOL/NatBin.thy
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    ID:         $Id$
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   1999  University of Cambridge
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*)
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header {* Binary arithmetic for the natural numbers *}
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theory NatBin
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imports IntDiv
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begin
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text {*
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  Arithmetic for naturals is reduced to that for the non-negative integers.
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*}
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instantiation nat :: number
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begin
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definition
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  nat_number_of_def [code inline]: "number_of v = nat (number_of v)"
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instance ..
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end
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lemma [code post]:
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  "nat (number_of v) = number_of v"
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  unfolding nat_number_of_def ..
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abbreviation (xsymbols)
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  square :: "'a::power => 'a"  ("(_\<twosuperior>)" [1000] 999) where
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  "x\<twosuperior> == x^2"
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notation (latex output)
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  square  ("(_\<twosuperior>)" [1000] 999)
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notation (HTML output)
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  square  ("(_\<twosuperior>)" [1000] 999)
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subsection{*Function @{term nat}: Coercion from Type @{typ int} to @{typ nat}*}
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declare nat_0 [simp] nat_1 [simp]
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lemma nat_number_of [simp]: "nat (number_of w) = number_of w"
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by (simp add: nat_number_of_def)
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lemma nat_numeral_0_eq_0 [simp]: "Numeral0 = (0::nat)"
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by (simp add: nat_number_of_def)
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lemma nat_numeral_1_eq_1 [simp]: "Numeral1 = (1::nat)"
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by (simp add: nat_1 nat_number_of_def)
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lemma numeral_1_eq_Suc_0: "Numeral1 = Suc 0"
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by (simp add: nat_numeral_1_eq_1)
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lemma numeral_2_eq_2: "2 = Suc (Suc 0)"
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apply (unfold nat_number_of_def)
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apply (rule nat_2)
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done
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text{*Distributive laws for type @{text nat}.  The others are in theory
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   @{text IntArith}, but these require div and mod to be defined for type
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   "int".  They also need some of the lemmas proved above.*}
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lemma nat_div_distrib: "(0::int) <= z ==> nat (z div z') = nat z div nat z'"
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apply (case_tac "0 <= z'")
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apply (auto simp add: div_nonneg_neg_le0 DIVISION_BY_ZERO_DIV)
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apply (case_tac "z' = 0", simp add: DIVISION_BY_ZERO)
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apply (auto elim!: nonneg_eq_int)
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apply (rename_tac m m')
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apply (subgoal_tac "0 <= int m div int m'")
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 prefer 2 apply (simp add: nat_numeral_0_eq_0 pos_imp_zdiv_nonneg_iff) 
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apply (rule of_nat_eq_iff [where 'a=int, THEN iffD1], simp)
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apply (rule_tac r = "int (m mod m') " in quorem_div)
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 prefer 2 apply force
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apply (simp add: nat_less_iff [symmetric] quorem_def nat_numeral_0_eq_0
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                 of_nat_add [symmetric] of_nat_mult [symmetric]
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            del: of_nat_add of_nat_mult)
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done
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(*Fails if z'<0: the LHS collapses to (nat z) but the RHS doesn't*)
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lemma nat_mod_distrib:
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     "[| (0::int) <= z;  0 <= z' |] ==> nat (z mod z') = nat z mod nat z'"
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apply (case_tac "z' = 0", simp add: DIVISION_BY_ZERO)
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apply (auto elim!: nonneg_eq_int)
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apply (rename_tac m m')
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apply (subgoal_tac "0 <= int m mod int m'")
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 prefer 2 apply (simp add: nat_less_iff nat_numeral_0_eq_0 pos_mod_sign)
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apply (rule int_int_eq [THEN iffD1], simp)
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apply (rule_tac q = "int (m div m') " in quorem_mod)
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 prefer 2 apply force
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apply (simp add: nat_less_iff [symmetric] quorem_def nat_numeral_0_eq_0
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                 of_nat_add [symmetric] of_nat_mult [symmetric]
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            del: of_nat_add of_nat_mult)
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done
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text{*Suggested by Matthias Daum*}
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lemma int_div_less_self: "\<lbrakk>0 < x; 1 < k\<rbrakk> \<Longrightarrow> x div k < (x::int)"
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apply (subgoal_tac "nat x div nat k < nat x")
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 apply (simp (asm_lr) add: nat_div_distrib [symmetric])
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apply (rule Divides.div_less_dividend, simp_all) 
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done
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subsection{*Function @{term int}: Coercion from Type @{typ nat} to @{typ int}*}
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(*"neg" is used in rewrite rules for binary comparisons*)
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lemma int_nat_number_of [simp]:
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     "int (number_of v) =  
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         (if neg (number_of v :: int) then 0  
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          else (number_of v :: int))"
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by (simp del: nat_number_of
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	 add: neg_nat nat_number_of_def not_neg_nat add_assoc)
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subsubsection{*Successor *}
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lemma Suc_nat_eq_nat_zadd1: "(0::int) <= z ==> Suc (nat z) = nat (1 + z)"
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apply (rule sym)
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apply (simp add: nat_eq_iff int_Suc)
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done
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lemma Suc_nat_number_of_add:
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     "Suc (number_of v + n) =  
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        (if neg (number_of v :: int) then 1+n else number_of (Int.succ v) + n)" 
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by (simp del: nat_number_of 
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         add: nat_number_of_def neg_nat
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              Suc_nat_eq_nat_zadd1 number_of_succ) 
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lemma Suc_nat_number_of [simp]:
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     "Suc (number_of v) =  
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        (if neg (number_of v :: int) then 1 else number_of (Int.succ v))"
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apply (cut_tac n = 0 in Suc_nat_number_of_add)
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apply (simp cong del: if_weak_cong)
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done
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subsubsection{*Addition *}
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(*"neg" is used in rewrite rules for binary comparisons*)
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lemma add_nat_number_of [simp]:
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     "(number_of v :: nat) + number_of v' =  
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         (if neg (number_of v :: int) then number_of v'  
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          else if neg (number_of v' :: int) then number_of v  
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          else number_of (v + v'))"
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by (force dest!: neg_nat
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          simp del: nat_number_of
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          simp add: nat_number_of_def nat_add_distrib [symmetric]) 
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subsubsection{*Subtraction *}
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lemma diff_nat_eq_if:
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     "nat z - nat z' =  
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        (if neg z' then nat z   
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         else let d = z-z' in     
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              if neg d then 0 else nat d)"
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apply (simp add: Let_def nat_diff_distrib [symmetric] neg_eq_less_0 not_neg_eq_ge_0)
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done
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lemma diff_nat_number_of [simp]: 
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     "(number_of v :: nat) - number_of v' =  
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        (if neg (number_of v' :: int) then number_of v  
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         else let d = number_of (v + uminus v') in     
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              if neg d then 0 else nat d)"
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by (simp del: nat_number_of add: diff_nat_eq_if nat_number_of_def) 
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subsubsection{*Multiplication *}
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lemma mult_nat_number_of [simp]:
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     "(number_of v :: nat) * number_of v' =  
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       (if neg (number_of v :: int) then 0 else number_of (v * v'))"
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by (force dest!: neg_nat
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          simp del: nat_number_of
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          simp add: nat_number_of_def nat_mult_distrib [symmetric]) 
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subsubsection{*Quotient *}
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lemma div_nat_number_of [simp]:
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     "(number_of v :: nat)  div  number_of v' =  
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          (if neg (number_of v :: int) then 0  
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           else nat (number_of v div number_of v'))"
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by (force dest!: neg_nat
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          simp del: nat_number_of
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          simp add: nat_number_of_def nat_div_distrib [symmetric]) 
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lemma one_div_nat_number_of [simp]:
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     "(Suc 0)  div  number_of v' = (nat (1 div number_of v'))" 
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by (simp del: nat_numeral_1_eq_1 add: numeral_1_eq_Suc_0 [symmetric]) 
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subsubsection{*Remainder *}
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lemma mod_nat_number_of [simp]:
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     "(number_of v :: nat)  mod  number_of v' =  
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        (if neg (number_of v :: int) then 0  
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         else if neg (number_of v' :: int) then number_of v  
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         else nat (number_of v mod number_of v'))"
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by (force dest!: neg_nat
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          simp del: nat_number_of
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          simp add: nat_number_of_def nat_mod_distrib [symmetric]) 
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lemma one_mod_nat_number_of [simp]:
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     "(Suc 0)  mod  number_of v' =  
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        (if neg (number_of v' :: int) then Suc 0
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         else nat (1 mod number_of v'))"
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by (simp del: nat_numeral_1_eq_1 add: numeral_1_eq_Suc_0 [symmetric]) 
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subsubsection{* Divisibility *}
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lemmas dvd_eq_mod_eq_0_number_of =
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  dvd_eq_mod_eq_0 [of "number_of x" "number_of y", standard]
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declare dvd_eq_mod_eq_0_number_of [simp]
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ML
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{*
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val nat_number_of_def = thm"nat_number_of_def";
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val nat_number_of = thm"nat_number_of";
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val nat_numeral_0_eq_0 = thm"nat_numeral_0_eq_0";
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val nat_numeral_1_eq_1 = thm"nat_numeral_1_eq_1";
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val numeral_1_eq_Suc_0 = thm"numeral_1_eq_Suc_0";
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val numeral_2_eq_2 = thm"numeral_2_eq_2";
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val nat_div_distrib = thm"nat_div_distrib";
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val nat_mod_distrib = thm"nat_mod_distrib";
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val int_nat_number_of = thm"int_nat_number_of";
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val Suc_nat_eq_nat_zadd1 = thm"Suc_nat_eq_nat_zadd1";
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val Suc_nat_number_of_add = thm"Suc_nat_number_of_add";
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val Suc_nat_number_of = thm"Suc_nat_number_of";
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val add_nat_number_of = thm"add_nat_number_of";
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val diff_nat_eq_if = thm"diff_nat_eq_if";
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val diff_nat_number_of = thm"diff_nat_number_of";
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val mult_nat_number_of = thm"mult_nat_number_of";
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val div_nat_number_of = thm"div_nat_number_of";
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val mod_nat_number_of = thm"mod_nat_number_of";
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*}
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subsection{*Comparisons*}
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subsubsection{*Equals (=) *}
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lemma eq_nat_nat_iff:
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     "[| (0::int) <= z;  0 <= z' |] ==> (nat z = nat z') = (z=z')"
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by (auto elim!: nonneg_eq_int)
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(*"neg" is used in rewrite rules for binary comparisons*)
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lemma eq_nat_number_of [simp]:
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     "((number_of v :: nat) = number_of v') =  
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      (if neg (number_of v :: int) then (iszero (number_of v' :: int) | neg (number_of v' :: int))  
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       else if neg (number_of v' :: int) then iszero (number_of v :: int)  
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       else iszero (number_of (v + uminus v') :: int))"
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apply (simp only: simp_thms neg_nat not_neg_eq_ge_0 nat_number_of_def
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                  eq_nat_nat_iff eq_number_of_eq nat_0 iszero_def
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            split add: split_if cong add: imp_cong)
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apply (simp only: nat_eq_iff nat_eq_iff2)
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apply (simp add: not_neg_eq_ge_0 [symmetric])
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done
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subsubsection{*Less-than (<) *}
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(*"neg" is used in rewrite rules for binary comparisons*)
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lemma less_nat_number_of [simp]:
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     "((number_of v :: nat) < number_of v') =  
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         (if neg (number_of v :: int) then neg (number_of (uminus v') :: int)  
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          else neg (number_of (v + uminus v') :: int))"
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by (simp only: simp_thms neg_nat not_neg_eq_ge_0 nat_number_of_def
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                nat_less_eq_zless less_number_of_eq_neg zless_nat_eq_int_zless
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         cong add: imp_cong, simp add: Pls_def)
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(*Maps #n to n for n = 0, 1, 2*)
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lemmas numerals = nat_numeral_0_eq_0 nat_numeral_1_eq_1 numeral_2_eq_2
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subsection{*Powers with Numeric Exponents*}
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text{*We cannot refer to the number @{term 2} in @{text Ring_and_Field.thy}.
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We cannot prove general results about the numeral @{term "-1"}, so we have to
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use @{term "- 1"} instead.*}
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lemma power2_eq_square: "(a::'a::recpower)\<twosuperior> = a * a"
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  by (simp add: numeral_2_eq_2 Power.power_Suc)
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lemma zero_power2 [simp]: "(0::'a::{semiring_1,recpower})\<twosuperior> = 0"
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  by (simp add: power2_eq_square)
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lemma one_power2 [simp]: "(1::'a::{semiring_1,recpower})\<twosuperior> = 1"
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  by (simp add: power2_eq_square)
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lemma power3_eq_cube: "(x::'a::recpower) ^ 3 = x * x * x"
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  apply (subgoal_tac "3 = Suc (Suc (Suc 0))")
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  apply (erule ssubst)
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  apply (simp add: power_Suc mult_ac)
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  apply (unfold nat_number_of_def)
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  apply (subst nat_eq_iff)
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  apply simp
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done
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text{*Squares of literal numerals will be evaluated.*}
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lemmas power2_eq_square_number_of =
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    power2_eq_square [of "number_of w", standard]
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declare power2_eq_square_number_of [simp]
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lemma zero_le_power2[simp]: "0 \<le> (a\<twosuperior>::'a::{ordered_idom,recpower})"
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  by (simp add: power2_eq_square)
wenzelm@23164
   317
wenzelm@23164
   318
lemma zero_less_power2[simp]:
wenzelm@23164
   319
     "(0 < a\<twosuperior>) = (a \<noteq> (0::'a::{ordered_idom,recpower}))"
wenzelm@23164
   320
  by (force simp add: power2_eq_square zero_less_mult_iff linorder_neq_iff)
wenzelm@23164
   321
wenzelm@23164
   322
lemma power2_less_0[simp]:
wenzelm@23164
   323
  fixes a :: "'a::{ordered_idom,recpower}"
wenzelm@23164
   324
  shows "~ (a\<twosuperior> < 0)"
wenzelm@23164
   325
by (force simp add: power2_eq_square mult_less_0_iff) 
wenzelm@23164
   326
wenzelm@23164
   327
lemma zero_eq_power2[simp]:
wenzelm@23164
   328
     "(a\<twosuperior> = 0) = (a = (0::'a::{ordered_idom,recpower}))"
wenzelm@23164
   329
  by (force simp add: power2_eq_square mult_eq_0_iff)
wenzelm@23164
   330
wenzelm@23164
   331
lemma abs_power2[simp]:
wenzelm@23164
   332
     "abs(a\<twosuperior>) = (a\<twosuperior>::'a::{ordered_idom,recpower})"
wenzelm@23164
   333
  by (simp add: power2_eq_square abs_mult abs_mult_self)
wenzelm@23164
   334
wenzelm@23164
   335
lemma power2_abs[simp]:
wenzelm@23164
   336
     "(abs a)\<twosuperior> = (a\<twosuperior>::'a::{ordered_idom,recpower})"
wenzelm@23164
   337
  by (simp add: power2_eq_square abs_mult_self)
wenzelm@23164
   338
wenzelm@23164
   339
lemma power2_minus[simp]:
wenzelm@23164
   340
     "(- a)\<twosuperior> = (a\<twosuperior>::'a::{comm_ring_1,recpower})"
wenzelm@23164
   341
  by (simp add: power2_eq_square)
wenzelm@23164
   342
wenzelm@23164
   343
lemma power2_le_imp_le:
wenzelm@23164
   344
  fixes x y :: "'a::{ordered_semidom,recpower}"
wenzelm@23164
   345
  shows "\<lbrakk>x\<twosuperior> \<le> y\<twosuperior>; 0 \<le> y\<rbrakk> \<Longrightarrow> x \<le> y"
wenzelm@23164
   346
unfolding numeral_2_eq_2 by (rule power_le_imp_le_base)
wenzelm@23164
   347
wenzelm@23164
   348
lemma power2_less_imp_less:
wenzelm@23164
   349
  fixes x y :: "'a::{ordered_semidom,recpower}"
wenzelm@23164
   350
  shows "\<lbrakk>x\<twosuperior> < y\<twosuperior>; 0 \<le> y\<rbrakk> \<Longrightarrow> x < y"
wenzelm@23164
   351
by (rule power_less_imp_less_base)
wenzelm@23164
   352
wenzelm@23164
   353
lemma power2_eq_imp_eq:
wenzelm@23164
   354
  fixes x y :: "'a::{ordered_semidom,recpower}"
wenzelm@23164
   355
  shows "\<lbrakk>x\<twosuperior> = y\<twosuperior>; 0 \<le> x; 0 \<le> y\<rbrakk> \<Longrightarrow> x = y"
wenzelm@23164
   356
unfolding numeral_2_eq_2 by (erule (2) power_eq_imp_eq_base, simp)
wenzelm@23164
   357
wenzelm@23164
   358
lemma power_minus1_even[simp]: "(- 1) ^ (2*n) = (1::'a::{comm_ring_1,recpower})"
wenzelm@23164
   359
apply (induct "n")
wenzelm@23164
   360
apply (auto simp add: power_Suc power_add)
wenzelm@23164
   361
done
wenzelm@23164
   362
wenzelm@23164
   363
lemma power_even_eq: "(a::'a::recpower) ^ (2*n) = (a^n)^2"
wenzelm@23164
   364
by (subst mult_commute) (simp add: power_mult)
wenzelm@23164
   365
wenzelm@23164
   366
lemma power_odd_eq: "(a::int) ^ Suc(2*n) = a * (a^n)^2"
wenzelm@23164
   367
by (simp add: power_even_eq) 
wenzelm@23164
   368
wenzelm@23164
   369
lemma power_minus_even [simp]:
wenzelm@23164
   370
     "(-a) ^ (2*n) = (a::'a::{comm_ring_1,recpower}) ^ (2*n)"
wenzelm@23164
   371
by (simp add: power_minus1_even power_minus [of a]) 
wenzelm@23164
   372
wenzelm@23164
   373
lemma zero_le_even_power'[simp]:
wenzelm@23164
   374
     "0 \<le> (a::'a::{ordered_idom,recpower}) ^ (2*n)"
wenzelm@23164
   375
proof (induct "n")
wenzelm@23164
   376
  case 0
wenzelm@23164
   377
    show ?case by (simp add: zero_le_one)
wenzelm@23164
   378
next
wenzelm@23164
   379
  case (Suc n)
wenzelm@23164
   380
    have "a ^ (2 * Suc n) = (a*a) * a ^ (2*n)" 
wenzelm@23164
   381
      by (simp add: mult_ac power_add power2_eq_square)
wenzelm@23164
   382
    thus ?case
wenzelm@23164
   383
      by (simp add: prems zero_le_mult_iff)
wenzelm@23164
   384
qed
wenzelm@23164
   385
wenzelm@23164
   386
lemma odd_power_less_zero:
wenzelm@23164
   387
     "(a::'a::{ordered_idom,recpower}) < 0 ==> a ^ Suc(2*n) < 0"
wenzelm@23164
   388
proof (induct "n")
wenzelm@23164
   389
  case 0
wenzelm@23389
   390
  then show ?case by (simp add: Power.power_Suc)
wenzelm@23164
   391
next
wenzelm@23164
   392
  case (Suc n)
wenzelm@23389
   393
  have "a ^ Suc (2 * Suc n) = (a*a) * a ^ Suc(2*n)" 
wenzelm@23389
   394
    by (simp add: mult_ac power_add power2_eq_square Power.power_Suc)
wenzelm@23389
   395
  thus ?case
wenzelm@23389
   396
    by (simp add: prems mult_less_0_iff mult_neg_neg)
wenzelm@23164
   397
qed
wenzelm@23164
   398
wenzelm@23164
   399
lemma odd_0_le_power_imp_0_le:
wenzelm@23164
   400
     "0 \<le> a  ^ Suc(2*n) ==> 0 \<le> (a::'a::{ordered_idom,recpower})"
wenzelm@23164
   401
apply (insert odd_power_less_zero [of a n]) 
wenzelm@23164
   402
apply (force simp add: linorder_not_less [symmetric]) 
wenzelm@23164
   403
done
wenzelm@23164
   404
wenzelm@23164
   405
text{*Simprules for comparisons where common factors can be cancelled.*}
wenzelm@23164
   406
lemmas zero_compare_simps =
wenzelm@23164
   407
    add_strict_increasing add_strict_increasing2 add_increasing
wenzelm@23164
   408
    zero_le_mult_iff zero_le_divide_iff 
wenzelm@23164
   409
    zero_less_mult_iff zero_less_divide_iff 
wenzelm@23164
   410
    mult_le_0_iff divide_le_0_iff 
wenzelm@23164
   411
    mult_less_0_iff divide_less_0_iff 
wenzelm@23164
   412
    zero_le_power2 power2_less_0
wenzelm@23164
   413
wenzelm@23164
   414
subsubsection{*Nat *}
wenzelm@23164
   415
wenzelm@23164
   416
lemma Suc_pred': "0 < n ==> n = Suc(n - 1)"
wenzelm@23164
   417
by (simp add: numerals)
wenzelm@23164
   418
wenzelm@23164
   419
(*Expresses a natural number constant as the Suc of another one.
wenzelm@23164
   420
  NOT suitable for rewriting because n recurs in the condition.*)
wenzelm@23164
   421
lemmas expand_Suc = Suc_pred' [of "number_of v", standard]
wenzelm@23164
   422
wenzelm@23164
   423
subsubsection{*Arith *}
wenzelm@23164
   424
wenzelm@23164
   425
lemma Suc_eq_add_numeral_1: "Suc n = n + 1"
wenzelm@23164
   426
by (simp add: numerals)
wenzelm@23164
   427
wenzelm@23164
   428
lemma Suc_eq_add_numeral_1_left: "Suc n = 1 + n"
wenzelm@23164
   429
by (simp add: numerals)
wenzelm@23164
   430
wenzelm@23164
   431
(* These two can be useful when m = number_of... *)
wenzelm@23164
   432
wenzelm@23164
   433
lemma add_eq_if: "(m::nat) + n = (if m=0 then n else Suc ((m - 1) + n))"
wenzelm@23164
   434
apply (case_tac "m")
wenzelm@23164
   435
apply (simp_all add: numerals)
wenzelm@23164
   436
done
wenzelm@23164
   437
wenzelm@23164
   438
lemma mult_eq_if: "(m::nat) * n = (if m=0 then 0 else n + ((m - 1) * n))"
wenzelm@23164
   439
apply (case_tac "m")
wenzelm@23164
   440
apply (simp_all add: numerals)
wenzelm@23164
   441
done
wenzelm@23164
   442
wenzelm@23164
   443
lemma power_eq_if: "(p ^ m :: nat) = (if m=0 then 1 else p * (p ^ (m - 1)))"
wenzelm@23164
   444
apply (case_tac "m")
wenzelm@23164
   445
apply (simp_all add: numerals)
wenzelm@23164
   446
done
wenzelm@23164
   447
wenzelm@23164
   448
wenzelm@23164
   449
subsection{*Comparisons involving (0::nat) *}
wenzelm@23164
   450
wenzelm@23164
   451
text{*Simplification already does @{term "n<0"}, @{term "n\<le>0"} and @{term "0\<le>n"}.*}
wenzelm@23164
   452
wenzelm@23164
   453
lemma eq_number_of_0 [simp]:
wenzelm@23164
   454
     "(number_of v = (0::nat)) =  
wenzelm@23164
   455
      (if neg (number_of v :: int) then True else iszero (number_of v :: int))"
wenzelm@23164
   456
by (simp del: nat_numeral_0_eq_0 add: nat_numeral_0_eq_0 [symmetric] iszero_0)
wenzelm@23164
   457
wenzelm@23164
   458
lemma eq_0_number_of [simp]:
wenzelm@23164
   459
     "((0::nat) = number_of v) =  
wenzelm@23164
   460
      (if neg (number_of v :: int) then True else iszero (number_of v :: int))"
wenzelm@23164
   461
by (rule trans [OF eq_sym_conv eq_number_of_0])
wenzelm@23164
   462
wenzelm@23164
   463
lemma less_0_number_of [simp]:
wenzelm@23164
   464
     "((0::nat) < number_of v) = neg (number_of (uminus v) :: int)"
wenzelm@23164
   465
by (simp del: nat_numeral_0_eq_0 add: nat_numeral_0_eq_0 [symmetric] Pls_def)
wenzelm@23164
   466
wenzelm@23164
   467
wenzelm@23164
   468
lemma neg_imp_number_of_eq_0: "neg (number_of v :: int) ==> number_of v = (0::nat)"
wenzelm@23164
   469
by (simp del: nat_numeral_0_eq_0 add: nat_numeral_0_eq_0 [symmetric] iszero_0)
wenzelm@23164
   470
wenzelm@23164
   471
wenzelm@23164
   472
wenzelm@23164
   473
subsection{*Comparisons involving  @{term Suc} *}
wenzelm@23164
   474
wenzelm@23164
   475
lemma eq_number_of_Suc [simp]:
wenzelm@23164
   476
     "(number_of v = Suc n) =  
haftmann@25919
   477
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   478
         if neg pv then False else nat pv = n)"
wenzelm@23164
   479
apply (simp only: simp_thms Let_def neg_eq_less_0 linorder_not_less 
wenzelm@23164
   480
                  number_of_pred nat_number_of_def 
wenzelm@23164
   481
            split add: split_if)
wenzelm@23164
   482
apply (rule_tac x = "number_of v" in spec)
wenzelm@23164
   483
apply (auto simp add: nat_eq_iff)
wenzelm@23164
   484
done
wenzelm@23164
   485
wenzelm@23164
   486
lemma Suc_eq_number_of [simp]:
wenzelm@23164
   487
     "(Suc n = number_of v) =  
haftmann@25919
   488
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   489
         if neg pv then False else nat pv = n)"
wenzelm@23164
   490
by (rule trans [OF eq_sym_conv eq_number_of_Suc])
wenzelm@23164
   491
wenzelm@23164
   492
lemma less_number_of_Suc [simp]:
wenzelm@23164
   493
     "(number_of v < Suc n) =  
haftmann@25919
   494
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   495
         if neg pv then True else nat pv < n)"
wenzelm@23164
   496
apply (simp only: simp_thms Let_def neg_eq_less_0 linorder_not_less 
wenzelm@23164
   497
                  number_of_pred nat_number_of_def  
wenzelm@23164
   498
            split add: split_if)
wenzelm@23164
   499
apply (rule_tac x = "number_of v" in spec)
wenzelm@23164
   500
apply (auto simp add: nat_less_iff)
wenzelm@23164
   501
done
wenzelm@23164
   502
wenzelm@23164
   503
lemma less_Suc_number_of [simp]:
wenzelm@23164
   504
     "(Suc n < number_of v) =  
haftmann@25919
   505
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   506
         if neg pv then False else n < nat pv)"
wenzelm@23164
   507
apply (simp only: simp_thms Let_def neg_eq_less_0 linorder_not_less 
wenzelm@23164
   508
                  number_of_pred nat_number_of_def
wenzelm@23164
   509
            split add: split_if)
wenzelm@23164
   510
apply (rule_tac x = "number_of v" in spec)
wenzelm@23164
   511
apply (auto simp add: zless_nat_eq_int_zless)
wenzelm@23164
   512
done
wenzelm@23164
   513
wenzelm@23164
   514
lemma le_number_of_Suc [simp]:
wenzelm@23164
   515
     "(number_of v <= Suc n) =  
haftmann@25919
   516
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   517
         if neg pv then True else nat pv <= n)"
wenzelm@23164
   518
by (simp add: Let_def less_Suc_number_of linorder_not_less [symmetric])
wenzelm@23164
   519
wenzelm@23164
   520
lemma le_Suc_number_of [simp]:
wenzelm@23164
   521
     "(Suc n <= number_of v) =  
haftmann@25919
   522
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   523
         if neg pv then False else n <= nat pv)"
wenzelm@23164
   524
by (simp add: Let_def less_number_of_Suc linorder_not_less [symmetric])
wenzelm@23164
   525
wenzelm@23164
   526
haftmann@25919
   527
lemma eq_number_of_Pls_Min: "(Numeral0 ::int) ~= number_of Int.Min"
wenzelm@23164
   528
by auto
wenzelm@23164
   529
wenzelm@23164
   530
wenzelm@23164
   531
wenzelm@23164
   532
subsection{*Max and Min Combined with @{term Suc} *}
wenzelm@23164
   533
wenzelm@23164
   534
lemma max_number_of_Suc [simp]:
wenzelm@23164
   535
     "max (Suc n) (number_of v) =  
haftmann@25919
   536
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   537
         if neg pv then Suc n else Suc(max n (nat pv)))"
wenzelm@23164
   538
apply (simp only: Let_def neg_eq_less_0 number_of_pred nat_number_of_def 
wenzelm@23164
   539
            split add: split_if nat.split)
wenzelm@23164
   540
apply (rule_tac x = "number_of v" in spec) 
wenzelm@23164
   541
apply auto
wenzelm@23164
   542
done
wenzelm@23164
   543
 
wenzelm@23164
   544
lemma max_Suc_number_of [simp]:
wenzelm@23164
   545
     "max (number_of v) (Suc n) =  
haftmann@25919
   546
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   547
         if neg pv then Suc n else Suc(max (nat pv) n))"
wenzelm@23164
   548
apply (simp only: Let_def neg_eq_less_0 number_of_pred nat_number_of_def 
wenzelm@23164
   549
            split add: split_if nat.split)
wenzelm@23164
   550
apply (rule_tac x = "number_of v" in spec) 
wenzelm@23164
   551
apply auto
wenzelm@23164
   552
done
wenzelm@23164
   553
 
wenzelm@23164
   554
lemma min_number_of_Suc [simp]:
wenzelm@23164
   555
     "min (Suc n) (number_of v) =  
haftmann@25919
   556
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   557
         if neg pv then 0 else Suc(min n (nat pv)))"
wenzelm@23164
   558
apply (simp only: Let_def neg_eq_less_0 number_of_pred nat_number_of_def 
wenzelm@23164
   559
            split add: split_if nat.split)
wenzelm@23164
   560
apply (rule_tac x = "number_of v" in spec) 
wenzelm@23164
   561
apply auto
wenzelm@23164
   562
done
wenzelm@23164
   563
 
wenzelm@23164
   564
lemma min_Suc_number_of [simp]:
wenzelm@23164
   565
     "min (number_of v) (Suc n) =  
haftmann@25919
   566
        (let pv = number_of (Int.pred v) in  
wenzelm@23164
   567
         if neg pv then 0 else Suc(min (nat pv) n))"
wenzelm@23164
   568
apply (simp only: Let_def neg_eq_less_0 number_of_pred nat_number_of_def 
wenzelm@23164
   569
            split add: split_if nat.split)
wenzelm@23164
   570
apply (rule_tac x = "number_of v" in spec) 
wenzelm@23164
   571
apply auto
wenzelm@23164
   572
done
wenzelm@23164
   573
 
wenzelm@23164
   574
subsection{*Literal arithmetic involving powers*}
wenzelm@23164
   575
wenzelm@23164
   576
lemma nat_power_eq: "(0::int) <= z ==> nat (z^n) = nat z ^ n"
wenzelm@23164
   577
apply (induct "n")
wenzelm@23164
   578
apply (simp_all (no_asm_simp) add: nat_mult_distrib)
wenzelm@23164
   579
done
wenzelm@23164
   580
wenzelm@23164
   581
lemma power_nat_number_of:
wenzelm@23164
   582
     "(number_of v :: nat) ^ n =  
wenzelm@23164
   583
       (if neg (number_of v :: int) then 0^n else nat ((number_of v :: int) ^ n))"
wenzelm@23164
   584
by (simp only: simp_thms neg_nat not_neg_eq_ge_0 nat_number_of_def nat_power_eq
wenzelm@23164
   585
         split add: split_if cong: imp_cong)
wenzelm@23164
   586
wenzelm@23164
   587
wenzelm@23164
   588
lemmas power_nat_number_of_number_of = power_nat_number_of [of _ "number_of w", standard]
wenzelm@23164
   589
declare power_nat_number_of_number_of [simp]
wenzelm@23164
   590
wenzelm@23164
   591
wenzelm@23164
   592
huffman@23294
   593
text{*For arbitrary rings*}
wenzelm@23164
   594
huffman@23294
   595
lemma power_number_of_even:
huffman@23294
   596
  fixes z :: "'a::{number_ring,recpower}"
huffman@26086
   597
  shows "z ^ number_of (Int.Bit0 w) = (let w = z ^ (number_of w) in w * w)"
huffman@26086
   598
unfolding Let_def nat_number_of_def number_of_Bit0
wenzelm@23164
   599
apply (rule_tac x = "number_of w" in spec, clarify)
wenzelm@23164
   600
apply (case_tac " (0::int) <= x")
wenzelm@23164
   601
apply (auto simp add: nat_mult_distrib power_even_eq power2_eq_square)
wenzelm@23164
   602
done
wenzelm@23164
   603
huffman@23294
   604
lemma power_number_of_odd:
huffman@23294
   605
  fixes z :: "'a::{number_ring,recpower}"
huffman@26086
   606
  shows "z ^ number_of (Int.Bit1 w) = (if (0::int) <= number_of w
wenzelm@23164
   607
     then (let w = z ^ (number_of w) in z * w * w) else 1)"
huffman@26086
   608
unfolding Let_def nat_number_of_def number_of_Bit1
wenzelm@23164
   609
apply (rule_tac x = "number_of w" in spec, auto)
wenzelm@23164
   610
apply (simp only: nat_add_distrib nat_mult_distrib)
wenzelm@23164
   611
apply simp
huffman@23294
   612
apply (auto simp add: nat_add_distrib nat_mult_distrib power_even_eq power2_eq_square neg_nat power_Suc)
wenzelm@23164
   613
done
wenzelm@23164
   614
huffman@23294
   615
lemmas zpower_number_of_even = power_number_of_even [where 'a=int]
huffman@23294
   616
lemmas zpower_number_of_odd = power_number_of_odd [where 'a=int]
wenzelm@23164
   617
huffman@23294
   618
lemmas power_number_of_even_number_of [simp] =
huffman@23294
   619
    power_number_of_even [of "number_of v", standard]
wenzelm@23164
   620
huffman@23294
   621
lemmas power_number_of_odd_number_of [simp] =
huffman@23294
   622
    power_number_of_odd [of "number_of v", standard]
wenzelm@23164
   623
wenzelm@23164
   624
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   625
wenzelm@23164
   626
ML
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   627
{*
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   628
val numeral_ss = @{simpset} addsimps @{thms numerals};
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   629
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   630
val nat_bin_arith_setup =
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   631
 LinArith.map_data
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   632
   (fn {add_mono_thms, mult_mono_thms, inj_thms, lessD, neqE, simpset} =>
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   633
     {add_mono_thms = add_mono_thms, mult_mono_thms = mult_mono_thms,
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   634
      inj_thms = inj_thms,
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   635
      lessD = lessD, neqE = neqE,
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   636
      simpset = simpset addsimps [Suc_nat_number_of, int_nat_number_of,
haftmann@25481
   637
        @{thm not_neg_number_of_Pls}, @{thm neg_number_of_Min},
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   638
        @{thm neg_number_of_Bit0}, @{thm neg_number_of_Bit1}]})
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   639
*}
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   640
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   641
declaration {* K nat_bin_arith_setup *}
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   642
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   643
(* Enable arith to deal with div/mod k where k is a numeral: *)
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   644
declare split_div[of _ _ "number_of k", standard, arith_split]
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   645
declare split_mod[of _ _ "number_of k", standard, arith_split]
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   646
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   647
lemma nat_number_of_Pls: "Numeral0 = (0::nat)"
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   648
  by (simp add: number_of_Pls nat_number_of_def)
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   649
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   650
lemma nat_number_of_Min: "number_of Int.Min = (0::nat)"
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   651
  apply (simp only: number_of_Min nat_number_of_def nat_zminus_int)
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   652
  done
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   653
huffman@26086
   654
lemma nat_number_of_Bit0:
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   655
    "number_of (Int.Bit0 w) = (let n::nat = number_of w in n + n)"
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   656
  apply (simp only: nat_number_of_def Let_def)
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   657
  apply (cases "neg (number_of w :: int)")
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   658
   apply (simp add: neg_nat neg_number_of_Bit0)
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   659
  apply (rule int_int_eq [THEN iffD1])
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   660
  apply (simp only: not_neg_nat neg_number_of_Bit0 int_Suc zadd_int [symmetric] simp_thms)
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   661
  apply (simp only: number_of_Bit0 zadd_assoc)
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   662
  apply simp
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   663
  done
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   664
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   665
lemma nat_number_of_Bit1:
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   666
  "number_of (Int.Bit1 w) =
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   667
    (if neg (number_of w :: int) then 0
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   668
     else let n = number_of w in Suc (n + n))"
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   669
  apply (simp only: nat_number_of_def Let_def split: split_if)
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   670
  apply (intro conjI impI)
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   671
   apply (simp add: neg_nat neg_number_of_Bit1)
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   672
  apply (rule int_int_eq [THEN iffD1])
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   673
  apply (simp only: not_neg_nat neg_number_of_Bit1 int_Suc zadd_int [symmetric] simp_thms)
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   674
  apply (simp only: number_of_Bit1 zadd_assoc)
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   675
  done
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   676
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   677
lemmas nat_number =
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   678
  nat_number_of_Pls nat_number_of_Min
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   679
  nat_number_of_Bit0 nat_number_of_Bit1
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   680
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   681
lemma Let_Suc [simp]: "Let (Suc n) f == f (Suc n)"
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   682
  by (simp add: Let_def)
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   683
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   684
lemma power_m1_even: "(-1) ^ (2*n) = (1::'a::{number_ring,recpower})"
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   685
by (simp add: power_mult power_Suc); 
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   686
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   687
lemma power_m1_odd: "(-1) ^ Suc(2*n) = (-1::'a::{number_ring,recpower})"
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   688
by (simp add: power_mult power_Suc); 
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   689
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   690
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   691
subsection{*Literal arithmetic and @{term of_nat}*}
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   692
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   693
lemma of_nat_double:
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   694
     "0 \<le> x ==> of_nat (nat (2 * x)) = of_nat (nat x) + of_nat (nat x)"
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   695
by (simp only: mult_2 nat_add_distrib of_nat_add) 
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   696
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   697
lemma nat_numeral_m1_eq_0: "-1 = (0::nat)"
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   698
by (simp only: nat_number_of_def)
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   699
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   700
lemma of_nat_number_of_lemma:
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   701
     "of_nat (number_of v :: nat) =  
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   702
         (if 0 \<le> (number_of v :: int) 
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   703
          then (number_of v :: 'a :: number_ring)
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   704
          else 0)"
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   705
by (simp add: int_number_of_def nat_number_of_def number_of_eq of_nat_nat);
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   706
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   707
lemma of_nat_number_of_eq [simp]:
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   708
     "of_nat (number_of v :: nat) =  
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   709
         (if neg (number_of v :: int) then 0  
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   710
          else (number_of v :: 'a :: number_ring))"
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   711
by (simp only: of_nat_number_of_lemma neg_def, simp) 
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   712
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   713
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   714
subsection {*Lemmas for the Combination and Cancellation Simprocs*}
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   715
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   716
lemma nat_number_of_add_left:
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   717
     "number_of v + (number_of v' + (k::nat)) =  
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   718
         (if neg (number_of v :: int) then number_of v' + k  
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   719
          else if neg (number_of v' :: int) then number_of v + k  
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   720
          else number_of (v + v') + k)"
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   721
by simp
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   722
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   723
lemma nat_number_of_mult_left:
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   724
     "number_of v * (number_of v' * (k::nat)) =  
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   725
         (if neg (number_of v :: int) then 0
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   726
          else number_of (v * v') * k)"
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   727
by simp
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   728
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   729
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   730
subsubsection{*For @{text combine_numerals}*}
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   731
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lemma left_add_mult_distrib: "i*u + (j*u + k) = (i+j)*u + (k::nat)"
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   733
by (simp add: add_mult_distrib)
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   734
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   735
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   736
subsubsection{*For @{text cancel_numerals}*}
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   737
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   738
lemma nat_diff_add_eq1:
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   739
     "j <= (i::nat) ==> ((i*u + m) - (j*u + n)) = (((i-j)*u + m) - n)"
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   740
by (simp split add: nat_diff_split add: add_mult_distrib)
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   741
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   742
lemma nat_diff_add_eq2:
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   743
     "i <= (j::nat) ==> ((i*u + m) - (j*u + n)) = (m - ((j-i)*u + n))"
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   744
by (simp split add: nat_diff_split add: add_mult_distrib)
wenzelm@23164
   745
wenzelm@23164
   746
lemma nat_eq_add_iff1:
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   747
     "j <= (i::nat) ==> (i*u + m = j*u + n) = ((i-j)*u + m = n)"
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   748
by (auto split add: nat_diff_split simp add: add_mult_distrib)
wenzelm@23164
   749
wenzelm@23164
   750
lemma nat_eq_add_iff2:
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   751
     "i <= (j::nat) ==> (i*u + m = j*u + n) = (m = (j-i)*u + n)"
wenzelm@23164
   752
by (auto split add: nat_diff_split simp add: add_mult_distrib)
wenzelm@23164
   753
wenzelm@23164
   754
lemma nat_less_add_iff1:
wenzelm@23164
   755
     "j <= (i::nat) ==> (i*u + m < j*u + n) = ((i-j)*u + m < n)"
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   756
by (auto split add: nat_diff_split simp add: add_mult_distrib)
wenzelm@23164
   757
wenzelm@23164
   758
lemma nat_less_add_iff2:
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   759
     "i <= (j::nat) ==> (i*u + m < j*u + n) = (m < (j-i)*u + n)"
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   760
by (auto split add: nat_diff_split simp add: add_mult_distrib)
wenzelm@23164
   761
wenzelm@23164
   762
lemma nat_le_add_iff1:
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   763
     "j <= (i::nat) ==> (i*u + m <= j*u + n) = ((i-j)*u + m <= n)"
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   764
by (auto split add: nat_diff_split simp add: add_mult_distrib)
wenzelm@23164
   765
wenzelm@23164
   766
lemma nat_le_add_iff2:
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   767
     "i <= (j::nat) ==> (i*u + m <= j*u + n) = (m <= (j-i)*u + n)"
wenzelm@23164
   768
by (auto split add: nat_diff_split simp add: add_mult_distrib)
wenzelm@23164
   769
wenzelm@23164
   770
wenzelm@23164
   771
subsubsection{*For @{text cancel_numeral_factors} *}
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   772
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   773
lemma nat_mult_le_cancel1: "(0::nat) < k ==> (k*m <= k*n) = (m<=n)"
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   774
by auto
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   775
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   776
lemma nat_mult_less_cancel1: "(0::nat) < k ==> (k*m < k*n) = (m<n)"
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   777
by auto
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   778
wenzelm@23164
   779
lemma nat_mult_eq_cancel1: "(0::nat) < k ==> (k*m = k*n) = (m=n)"
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   780
by auto
wenzelm@23164
   781
wenzelm@23164
   782
lemma nat_mult_div_cancel1: "(0::nat) < k ==> (k*m) div (k*n) = (m div n)"
wenzelm@23164
   783
by auto
wenzelm@23164
   784
nipkow@23969
   785
lemma nat_mult_dvd_cancel_disj[simp]:
nipkow@23969
   786
  "(k*m) dvd (k*n) = (k=0 | m dvd (n::nat))"
nipkow@23969
   787
by(auto simp: dvd_eq_mod_eq_0 mod_mult_distrib2[symmetric])
nipkow@23969
   788
nipkow@23969
   789
lemma nat_mult_dvd_cancel1: "0 < k \<Longrightarrow> (k*m) dvd (k*n::nat) = (m dvd n)"
nipkow@23969
   790
by(auto)
nipkow@23969
   791
wenzelm@23164
   792
wenzelm@23164
   793
subsubsection{*For @{text cancel_factor} *}
wenzelm@23164
   794
wenzelm@23164
   795
lemma nat_mult_le_cancel_disj: "(k*m <= k*n) = ((0::nat) < k --> m<=n)"
wenzelm@23164
   796
by auto
wenzelm@23164
   797
wenzelm@23164
   798
lemma nat_mult_less_cancel_disj: "(k*m < k*n) = ((0::nat) < k & m<n)"
wenzelm@23164
   799
by auto
wenzelm@23164
   800
wenzelm@23164
   801
lemma nat_mult_eq_cancel_disj: "(k*m = k*n) = (k = (0::nat) | m=n)"
wenzelm@23164
   802
by auto
wenzelm@23164
   803
nipkow@23969
   804
lemma nat_mult_div_cancel_disj[simp]:
wenzelm@23164
   805
     "(k*m) div (k*n) = (if k = (0::nat) then 0 else m div n)"
wenzelm@23164
   806
by (simp add: nat_mult_div_cancel1)
wenzelm@23164
   807
wenzelm@23164
   808
end