author | wenzelm |
Fri, 06 May 2011 17:52:08 +0200 | |
changeset 42711 | 159c4d1d4c42 |
parent 35762 | af3ff2ba4c54 |
child 45608 | 13b101cee425 |
permissions | -rw-r--r-- |
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(* Title: ZF/Arith.thy |
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Author: Lawrence C Paulson, Cambridge University Computer Laboratory |
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Copyright 1992 University of Cambridge |
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*) |
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(*"Difference" is subtraction of natural numbers. |
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There are no negative numbers; we have |
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m #- n = 0 iff m<=n and m #- n = succ(k) iff m>n. |
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Also, rec(m, 0, %z w.z) is pred(m). |
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*) |
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header{*Arithmetic Operators and Their Definitions*} |
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theory Arith imports Univ begin |
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text{*Proofs about elementary arithmetic: addition, multiplication, etc.*} |
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definition |
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pred :: "i=>i" (*inverse of succ*) where |
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"pred(y) == nat_case(0, %x. x, y)" |
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definition |
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natify :: "i=>i" (*coerces non-nats to nats*) where |
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"natify == Vrecursor(%f a. if a = succ(pred(a)) then succ(f`pred(a)) |
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else 0)" |
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consts |
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raw_add :: "[i,i]=>i" |
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raw_diff :: "[i,i]=>i" |
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raw_mult :: "[i,i]=>i" |
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primrec |
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"raw_add (0, n) = n" |
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"raw_add (succ(m), n) = succ(raw_add(m, n))" |
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primrec |
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raw_diff_0: "raw_diff(m, 0) = m" |
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raw_diff_succ: "raw_diff(m, succ(n)) = |
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nat_case(0, %x. x, raw_diff(m, n))" |
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primrec |
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"raw_mult(0, n) = 0" |
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"raw_mult(succ(m), n) = raw_add (n, raw_mult(m, n))" |
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definition |
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add :: "[i,i]=>i" (infixl "#+" 65) where |
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"m #+ n == raw_add (natify(m), natify(n))" |
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definition |
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diff :: "[i,i]=>i" (infixl "#-" 65) where |
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"m #- n == raw_diff (natify(m), natify(n))" |
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definition |
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mult :: "[i,i]=>i" (infixl "#*" 70) where |
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"m #* n == raw_mult (natify(m), natify(n))" |
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definition |
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raw_div :: "[i,i]=>i" where |
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"raw_div (m, n) == |
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transrec(m, %j f. if j<n | n=0 then 0 else succ(f`(j#-n)))" |
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definition |
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raw_mod :: "[i,i]=>i" where |
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"raw_mod (m, n) == |
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transrec(m, %j f. if j<n | n=0 then j else f`(j#-n))" |
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definition |
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div :: "[i,i]=>i" (infixl "div" 70) where |
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"m div n == raw_div (natify(m), natify(n))" |
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definition |
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mod :: "[i,i]=>i" (infixl "mod" 70) where |
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"m mod n == raw_mod (natify(m), natify(n))" |
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notation (xsymbols) |
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mult (infixr "#\<times>" 70) |
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notation (HTML output) |
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mult (infixr "#\<times>" 70) |
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declare rec_type [simp] |
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nat_0_le [simp] |
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lemma zero_lt_lemma: "[| 0<k; k \<in> nat |] ==> \<exists>j\<in>nat. k = succ(j)" |
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apply (erule rev_mp) |
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apply (induct_tac "k", auto) |
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done |
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(* [| 0 < k; k \<in> nat; !!j. [| j \<in> nat; k = succ(j) |] ==> Q |] ==> Q *) |
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lemmas zero_lt_natE = zero_lt_lemma [THEN bexE, standard] |
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subsection{*@{text natify}, the Coercion to @{term nat}*} |
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lemma pred_succ_eq [simp]: "pred(succ(y)) = y" |
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by (unfold pred_def, auto) |
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lemma natify_succ: "natify(succ(x)) = succ(natify(x))" |
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by (rule natify_def [THEN def_Vrecursor, THEN trans], auto) |
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lemma natify_0 [simp]: "natify(0) = 0" |
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by (rule natify_def [THEN def_Vrecursor, THEN trans], auto) |
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lemma natify_non_succ: "\<forall>z. x ~= succ(z) ==> natify(x) = 0" |
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by (rule natify_def [THEN def_Vrecursor, THEN trans], auto) |
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lemma natify_in_nat [iff,TC]: "natify(x) \<in> nat" |
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apply (rule_tac a=x in eps_induct) |
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apply (case_tac "\<exists>z. x = succ(z)") |
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apply (auto simp add: natify_succ natify_non_succ) |
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done |
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lemma natify_ident [simp]: "n \<in> nat ==> natify(n) = n" |
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apply (induct_tac "n") |
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apply (auto simp add: natify_succ) |
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done |
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lemma natify_eqE: "[|natify(x) = y; x \<in> nat|] ==> x=y" |
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by auto |
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(*** Collapsing rules: to remove natify from arithmetic expressions ***) |
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lemma natify_idem [simp]: "natify(natify(x)) = natify(x)" |
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by simp |
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(** Addition **) |
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lemma add_natify1 [simp]: "natify(m) #+ n = m #+ n" |
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by (simp add: add_def) |
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lemma add_natify2 [simp]: "m #+ natify(n) = m #+ n" |
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by (simp add: add_def) |
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(** Multiplication **) |
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lemma mult_natify1 [simp]: "natify(m) #* n = m #* n" |
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by (simp add: mult_def) |
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lemma mult_natify2 [simp]: "m #* natify(n) = m #* n" |
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by (simp add: mult_def) |
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(** Difference **) |
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lemma diff_natify1 [simp]: "natify(m) #- n = m #- n" |
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by (simp add: diff_def) |
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lemma diff_natify2 [simp]: "m #- natify(n) = m #- n" |
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by (simp add: diff_def) |
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(** Remainder **) |
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lemma mod_natify1 [simp]: "natify(m) mod n = m mod n" |
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by (simp add: mod_def) |
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lemma mod_natify2 [simp]: "m mod natify(n) = m mod n" |
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by (simp add: mod_def) |
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(** Quotient **) |
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lemma div_natify1 [simp]: "natify(m) div n = m div n" |
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by (simp add: div_def) |
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lemma div_natify2 [simp]: "m div natify(n) = m div n" |
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by (simp add: div_def) |
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subsection{*Typing rules*} |
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(** Addition **) |
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lemma raw_add_type: "[| m\<in>nat; n\<in>nat |] ==> raw_add (m, n) \<in> nat" |
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by (induct_tac "m", auto) |
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lemma add_type [iff,TC]: "m #+ n \<in> nat" |
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by (simp add: add_def raw_add_type) |
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(** Multiplication **) |
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lemma raw_mult_type: "[| m\<in>nat; n\<in>nat |] ==> raw_mult (m, n) \<in> nat" |
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apply (induct_tac "m") |
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apply (simp_all add: raw_add_type) |
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done |
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lemma mult_type [iff,TC]: "m #* n \<in> nat" |
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by (simp add: mult_def raw_mult_type) |
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(** Difference **) |
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lemma raw_diff_type: "[| m\<in>nat; n\<in>nat |] ==> raw_diff (m, n) \<in> nat" |
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by (induct_tac "n", auto) |
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lemma diff_type [iff,TC]: "m #- n \<in> nat" |
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by (simp add: diff_def raw_diff_type) |
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lemma diff_0_eq_0 [simp]: "0 #- n = 0" |
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apply (unfold diff_def) |
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apply (rule natify_in_nat [THEN nat_induct], auto) |
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done |
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(*Must simplify BEFORE the induction: else we get a critical pair*) |
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lemma diff_succ_succ [simp]: "succ(m) #- succ(n) = m #- n" |
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apply (simp add: natify_succ diff_def) |
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apply (rule_tac x1 = n in natify_in_nat [THEN nat_induct], auto) |
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done |
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(*This defining property is no longer wanted*) |
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declare raw_diff_succ [simp del] |
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(*Natify has weakened this law, compared with the older approach*) |
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lemma diff_0 [simp]: "m #- 0 = natify(m)" |
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by (simp add: diff_def) |
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lemma diff_le_self: "m\<in>nat ==> (m #- n) le m" |
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apply (subgoal_tac " (m #- natify (n)) le m") |
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apply (rule_tac [2] m = m and n = "natify (n) " in diff_induct) |
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apply (erule_tac [6] leE) |
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apply (simp_all add: le_iff) |
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done |
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subsection{*Addition*} |
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(*Natify has weakened this law, compared with the older approach*) |
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lemma add_0_natify [simp]: "0 #+ m = natify(m)" |
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by (simp add: add_def) |
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lemma add_succ [simp]: "succ(m) #+ n = succ(m #+ n)" |
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by (simp add: natify_succ add_def) |
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lemma add_0: "m \<in> nat ==> 0 #+ m = m" |
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by simp |
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(*Associative law for addition*) |
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lemma add_assoc: "(m #+ n) #+ k = m #+ (n #+ k)" |
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apply (subgoal_tac "(natify(m) #+ natify(n)) #+ natify(k) = |
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natify(m) #+ (natify(n) #+ natify(k))") |
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apply (rule_tac [2] n = "natify(m)" in nat_induct) |
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apply auto |
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done |
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(*The following two lemmas are used for add_commute and sometimes |
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elsewhere, since they are safe for rewriting.*) |
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lemma add_0_right_natify [simp]: "m #+ 0 = natify(m)" |
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apply (subgoal_tac "natify(m) #+ 0 = natify(m)") |
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apply (rule_tac [2] n = "natify(m)" in nat_induct) |
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apply auto |
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done |
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lemma add_succ_right [simp]: "m #+ succ(n) = succ(m #+ n)" |
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apply (unfold add_def) |
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apply (rule_tac n = "natify(m) " in nat_induct) |
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apply (auto simp add: natify_succ) |
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done |
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lemma add_0_right: "m \<in> nat ==> m #+ 0 = m" |
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by auto |
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(*Commutative law for addition*) |
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lemma add_commute: "m #+ n = n #+ m" |
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apply (subgoal_tac "natify(m) #+ natify(n) = natify(n) #+ natify(m) ") |
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apply (rule_tac [2] n = "natify(m) " in nat_induct) |
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apply auto |
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done |
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(*for a/c rewriting*) |
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lemma add_left_commute: "m#+(n#+k)=n#+(m#+k)" |
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apply (rule add_commute [THEN trans]) |
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apply (rule add_assoc [THEN trans]) |
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apply (rule add_commute [THEN subst_context]) |
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done |
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(*Addition is an AC-operator*) |
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lemmas add_ac = add_assoc add_commute add_left_commute |
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(*Cancellation law on the left*) |
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lemma raw_add_left_cancel: |
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"[| raw_add(k, m) = raw_add(k, n); k\<in>nat |] ==> m=n" |
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apply (erule rev_mp) |
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apply (induct_tac "k", auto) |
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done |
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lemma add_left_cancel_natify: "k #+ m = k #+ n ==> natify(m) = natify(n)" |
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apply (unfold add_def) |
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apply (drule raw_add_left_cancel, auto) |
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done |
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lemma add_left_cancel: |
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"[| i = j; i #+ m = j #+ n; m\<in>nat; n\<in>nat |] ==> m = n" |
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by (force dest!: add_left_cancel_natify) |
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(*Thanks to Sten Agerholm*) |
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lemma add_le_elim1_natify: "k#+m le k#+n ==> natify(m) le natify(n)" |
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apply (rule_tac P = "natify(k) #+m le natify(k) #+n" in rev_mp) |
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apply (rule_tac [2] n = "natify(k) " in nat_induct) |
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apply auto |
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done |
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lemma add_le_elim1: "[| k#+m le k#+n; m \<in> nat; n \<in> nat |] ==> m le n" |
13163 | 303 |
by (drule add_le_elim1_natify, auto) |
304 |
||
305 |
lemma add_lt_elim1_natify: "k#+m < k#+n ==> natify(m) < natify(n)" |
|
306 |
apply (rule_tac P = "natify(k) #+m < natify(k) #+n" in rev_mp) |
|
307 |
apply (rule_tac [2] n = "natify(k) " in nat_induct) |
|
308 |
apply auto |
|
309 |
done |
|
310 |
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lemma add_lt_elim1: "[| k#+m < k#+n; m \<in> nat; n \<in> nat |] ==> m < n" |
13163 | 312 |
by (drule add_lt_elim1_natify, auto) |
313 |
||
15201 | 314 |
lemma zero_less_add: "[| n \<in> nat; m \<in> nat |] ==> 0 < m #+ n <-> (0<m | 0<n)" |
315 |
by (induct_tac "n", auto) |
|
316 |
||
13163 | 317 |
|
13356 | 318 |
subsection{*Monotonicity of Addition*} |
13163 | 319 |
|
320 |
(*strict, in 1st argument; proof is by rule induction on 'less than'. |
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Still need j\<in>nat, for consider j = omega. Then we can have i<omega, |
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which is the same as i\<in>nat, but natify(j)=0, so the conclusion fails.*) |
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lemma add_lt_mono1: "[| i<j; j\<in>nat |] ==> i#+k < j#+k" |
13163 | 324 |
apply (frule lt_nat_in_nat, assumption) |
325 |
apply (erule succ_lt_induct) |
|
326 |
apply (simp_all add: leI) |
|
327 |
done |
|
328 |
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text{*strict, in second argument*} |
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lemma add_lt_mono2: "[| i<j; j\<in>nat |] ==> k#+i < k#+j" |
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by (simp add: add_commute [of k] add_lt_mono1) |
13163 | 332 |
|
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text{*A [clumsy] way of lifting < monotonicity to @{text "\<le>"} monotonicity*} |
13163 | 334 |
lemma Ord_lt_mono_imp_le_mono: |
335 |
assumes lt_mono: "!!i j. [| i<j; j:k |] ==> f(i) < f(j)" |
|
336 |
and ford: "!!i. i:k ==> Ord(f(i))" |
|
337 |
and leij: "i le j" |
|
338 |
and jink: "j:k" |
|
339 |
shows "f(i) le f(j)" |
|
340 |
apply (insert leij jink) |
|
341 |
apply (blast intro!: leCI lt_mono ford elim!: leE) |
|
342 |
done |
|
343 |
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text{*@{text "\<le>"} monotonicity, 1st argument*} |
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lemma add_le_mono1: "[| i le j; j\<in>nat |] ==> i#+k le j#+k" |
13163 | 346 |
apply (rule_tac f = "%j. j#+k" in Ord_lt_mono_imp_le_mono, typecheck) |
347 |
apply (blast intro: add_lt_mono1 add_type [THEN nat_into_Ord])+ |
|
348 |
done |
|
349 |
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text{*@{text "\<le>"} monotonicity, both arguments*} |
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351 |
lemma add_le_mono: "[| i le j; k le l; j\<in>nat; l\<in>nat |] ==> i#+k le j#+l" |
13163 | 352 |
apply (rule add_le_mono1 [THEN le_trans], assumption+) |
353 |
apply (subst add_commute, subst add_commute, rule add_le_mono1, assumption+) |
|
354 |
done |
|
355 |
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text{*Combinations of less-than and less-than-or-equals*} |
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357 |
|
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lemma add_lt_le_mono: "[| i<j; k\<le>l; j\<in>nat; l\<in>nat |] ==> i#+k < j#+l" |
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apply (rule add_lt_mono1 [THEN lt_trans2], assumption+) |
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apply (subst add_commute, subst add_commute, rule add_le_mono1, assumption+) |
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361 |
done |
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362 |
|
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363 |
lemma add_le_lt_mono: "[| i\<le>j; k<l; j\<in>nat; l\<in>nat |] ==> i#+k < j#+l" |
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364 |
by (subst add_commute, subst add_commute, erule add_lt_le_mono, assumption+) |
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365 |
|
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366 |
text{*Less-than: in other words, strict in both arguments*} |
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367 |
lemma add_lt_mono: "[| i<j; k<l; j\<in>nat; l\<in>nat |] ==> i#+k < j#+l" |
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368 |
apply (rule add_lt_le_mono) |
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apply (auto intro: leI) |
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370 |
done |
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371 |
|
13163 | 372 |
(** Subtraction is the inverse of addition. **) |
373 |
||
374 |
lemma diff_add_inverse: "(n#+m) #- n = natify(m)" |
|
375 |
apply (subgoal_tac " (natify(n) #+ m) #- natify(n) = natify(m) ") |
|
376 |
apply (rule_tac [2] n = "natify(n) " in nat_induct) |
|
377 |
apply auto |
|
378 |
done |
|
379 |
||
380 |
lemma diff_add_inverse2: "(m#+n) #- n = natify(m)" |
|
381 |
by (simp add: add_commute [of m] diff_add_inverse) |
|
382 |
||
383 |
lemma diff_cancel: "(k#+m) #- (k#+n) = m #- n" |
|
384 |
apply (subgoal_tac "(natify(k) #+ natify(m)) #- (natify(k) #+ natify(n)) = |
|
385 |
natify(m) #- natify(n) ") |
|
386 |
apply (rule_tac [2] n = "natify(k) " in nat_induct) |
|
387 |
apply auto |
|
388 |
done |
|
389 |
||
390 |
lemma diff_cancel2: "(m#+k) #- (n#+k) = m #- n" |
|
391 |
by (simp add: add_commute [of _ k] diff_cancel) |
|
392 |
||
393 |
lemma diff_add_0: "n #- (n#+m) = 0" |
|
394 |
apply (subgoal_tac "natify(n) #- (natify(n) #+ natify(m)) = 0") |
|
395 |
apply (rule_tac [2] n = "natify(n) " in nat_induct) |
|
396 |
apply auto |
|
397 |
done |
|
398 |
||
13361 | 399 |
lemma pred_0 [simp]: "pred(0) = 0" |
400 |
by (simp add: pred_def) |
|
401 |
||
402 |
lemma eq_succ_imp_eq_m1: "[|i = succ(j); i\<in>nat|] ==> j = i #- 1 & j \<in>nat" |
|
403 |
by simp |
|
404 |
||
405 |
lemma pred_Un_distrib: |
|
406 |
"[|i\<in>nat; j\<in>nat|] ==> pred(i Un j) = pred(i) Un pred(j)" |
|
407 |
apply (erule_tac n=i in natE, simp) |
|
408 |
apply (erule_tac n=j in natE, simp) |
|
409 |
apply (simp add: succ_Un_distrib [symmetric]) |
|
410 |
done |
|
411 |
||
412 |
lemma pred_type [TC,simp]: |
|
413 |
"i \<in> nat ==> pred(i) \<in> nat" |
|
414 |
by (simp add: pred_def split: split_nat_case) |
|
415 |
||
416 |
lemma nat_diff_pred: "[|i\<in>nat; j\<in>nat|] ==> i #- succ(j) = pred(i #- j)"; |
|
417 |
apply (rule_tac m=i and n=j in diff_induct) |
|
418 |
apply (auto simp add: pred_def nat_imp_quasinat split: split_nat_case) |
|
419 |
done |
|
420 |
||
421 |
lemma diff_succ_eq_pred: "i #- succ(j) = pred(i #- j)"; |
|
422 |
apply (insert nat_diff_pred [of "natify(i)" "natify(j)"]) |
|
423 |
apply (simp add: natify_succ [symmetric]) |
|
424 |
done |
|
425 |
||
426 |
lemma nat_diff_Un_distrib: |
|
427 |
"[|i\<in>nat; j\<in>nat; k\<in>nat|] ==> (i Un j) #- k = (i#-k) Un (j#-k)" |
|
428 |
apply (rule_tac n=k in nat_induct) |
|
429 |
apply (simp_all add: diff_succ_eq_pred pred_Un_distrib) |
|
430 |
done |
|
431 |
||
432 |
lemma diff_Un_distrib: |
|
433 |
"[|i\<in>nat; j\<in>nat|] ==> (i Un j) #- k = (i#-k) Un (j#-k)" |
|
434 |
by (insert nat_diff_Un_distrib [of i j "natify(k)"], simp) |
|
435 |
||
436 |
text{*We actually prove @{term "i #- j #- k = i #- (j #+ k)"}*} |
|
437 |
lemma diff_diff_left [simplified]: |
|
438 |
"natify(i)#-natify(j)#-k = natify(i) #- (natify(j)#+k)"; |
|
439 |
by (rule_tac m="natify(i)" and n="natify(j)" in diff_induct, auto) |
|
440 |
||
13163 | 441 |
|
442 |
(** Lemmas for the CancelNumerals simproc **) |
|
443 |
||
444 |
lemma eq_add_iff: "(u #+ m = u #+ n) <-> (0 #+ m = natify(n))" |
|
445 |
apply auto |
|
446 |
apply (blast dest: add_left_cancel_natify) |
|
447 |
apply (simp add: add_def) |
|
448 |
done |
|
449 |
||
450 |
lemma less_add_iff: "(u #+ m < u #+ n) <-> (0 #+ m < natify(n))" |
|
451 |
apply (auto simp add: add_lt_elim1_natify) |
|
452 |
apply (drule add_lt_mono1) |
|
453 |
apply (auto simp add: add_commute [of u]) |
|
454 |
done |
|
455 |
||
456 |
lemma diff_add_eq: "((u #+ m) #- (u #+ n)) = ((0 #+ m) #- n)" |
|
457 |
by (simp add: diff_cancel) |
|
458 |
||
459 |
(*To tidy up the result of a simproc. Only the RHS will be simplified.*) |
|
460 |
lemma eq_cong2: "u = u' ==> (t==u) == (t==u')" |
|
461 |
by auto |
|
462 |
||
463 |
lemma iff_cong2: "u <-> u' ==> (t==u) == (t==u')" |
|
464 |
by auto |
|
465 |
||
466 |
||
13356 | 467 |
subsection{*Multiplication*} |
13163 | 468 |
|
469 |
lemma mult_0 [simp]: "0 #* m = 0" |
|
470 |
by (simp add: mult_def) |
|
471 |
||
472 |
lemma mult_succ [simp]: "succ(m) #* n = n #+ (m #* n)" |
|
473 |
by (simp add: add_def mult_def natify_succ raw_mult_type) |
|
474 |
||
475 |
(*right annihilation in product*) |
|
476 |
lemma mult_0_right [simp]: "m #* 0 = 0" |
|
477 |
apply (unfold mult_def) |
|
478 |
apply (rule_tac n = "natify(m) " in nat_induct) |
|
479 |
apply auto |
|
480 |
done |
|
481 |
||
482 |
(*right successor law for multiplication*) |
|
483 |
lemma mult_succ_right [simp]: "m #* succ(n) = m #+ (m #* n)" |
|
484 |
apply (subgoal_tac "natify(m) #* succ (natify(n)) = |
|
485 |
natify(m) #+ (natify(m) #* natify(n))") |
|
486 |
apply (simp (no_asm_use) add: natify_succ add_def mult_def) |
|
487 |
apply (rule_tac n = "natify(m) " in nat_induct) |
|
488 |
apply (simp_all add: add_ac) |
|
489 |
done |
|
490 |
||
491 |
lemma mult_1_natify [simp]: "1 #* n = natify(n)" |
|
492 |
by auto |
|
493 |
||
494 |
lemma mult_1_right_natify [simp]: "n #* 1 = natify(n)" |
|
495 |
by auto |
|
496 |
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497 |
lemma mult_1: "n \<in> nat ==> 1 #* n = n" |
13163 | 498 |
by simp |
499 |
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500 |
lemma mult_1_right: "n \<in> nat ==> n #* 1 = n" |
13163 | 501 |
by simp |
502 |
||
503 |
(*Commutative law for multiplication*) |
|
504 |
lemma mult_commute: "m #* n = n #* m" |
|
505 |
apply (subgoal_tac "natify(m) #* natify(n) = natify(n) #* natify(m) ") |
|
506 |
apply (rule_tac [2] n = "natify(m) " in nat_induct) |
|
507 |
apply auto |
|
508 |
done |
|
509 |
||
510 |
(*addition distributes over multiplication*) |
|
511 |
lemma add_mult_distrib: "(m #+ n) #* k = (m #* k) #+ (n #* k)" |
|
512 |
apply (subgoal_tac "(natify(m) #+ natify(n)) #* natify(k) = |
|
513 |
(natify(m) #* natify(k)) #+ (natify(n) #* natify(k))") |
|
514 |
apply (rule_tac [2] n = "natify(m) " in nat_induct) |
|
515 |
apply (simp_all add: add_assoc [symmetric]) |
|
516 |
done |
|
517 |
||
518 |
(*Distributive law on the left*) |
|
519 |
lemma add_mult_distrib_left: "k #* (m #+ n) = (k #* m) #+ (k #* n)" |
|
520 |
apply (subgoal_tac "natify(k) #* (natify(m) #+ natify(n)) = |
|
521 |
(natify(k) #* natify(m)) #+ (natify(k) #* natify(n))") |
|
522 |
apply (rule_tac [2] n = "natify(m) " in nat_induct) |
|
523 |
apply (simp_all add: add_ac) |
|
524 |
done |
|
525 |
||
526 |
(*Associative law for multiplication*) |
|
527 |
lemma mult_assoc: "(m #* n) #* k = m #* (n #* k)" |
|
528 |
apply (subgoal_tac "(natify(m) #* natify(n)) #* natify(k) = |
|
529 |
natify(m) #* (natify(n) #* natify(k))") |
|
530 |
apply (rule_tac [2] n = "natify(m) " in nat_induct) |
|
531 |
apply (simp_all add: add_mult_distrib) |
|
532 |
done |
|
533 |
||
534 |
(*for a/c rewriting*) |
|
535 |
lemma mult_left_commute: "m #* (n #* k) = n #* (m #* k)" |
|
536 |
apply (rule mult_commute [THEN trans]) |
|
537 |
apply (rule mult_assoc [THEN trans]) |
|
538 |
apply (rule mult_commute [THEN subst_context]) |
|
539 |
done |
|
540 |
||
541 |
lemmas mult_ac = mult_assoc mult_commute mult_left_commute |
|
542 |
||
543 |
||
544 |
lemma lt_succ_eq_0_disj: |
|
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545 |
"[| m\<in>nat; n\<in>nat |] |
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546 |
==> (m < succ(n)) <-> (m = 0 | (\<exists>j\<in>nat. m = succ(j) & j < n))" |
13163 | 547 |
by (induct_tac "m", auto) |
548 |
||
549 |
lemma less_diff_conv [rule_format]: |
|
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550 |
"[| j\<in>nat; k\<in>nat |] ==> \<forall>i\<in>nat. (i < j #- k) <-> (i #+ k < j)" |
13784 | 551 |
by (erule_tac m = k in diff_induct, auto) |
13163 | 552 |
|
553 |
lemmas nat_typechecks = rec_type nat_0I nat_1I nat_succI Ord_nat |
|
554 |
||
0 | 555 |
end |