author  wenzelm 
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permissions  rwrr 
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(* Title: HOL/Nat.thy 
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Author: Tobias Nipkow 
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Author: Lawrence C Paulson 

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Author: Markus Wenzel 

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Type "nat" is a linear order, and a datatype; arithmetic operators +  
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and * (for div and mod, see theory Divides). 
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*) 
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section \<open>Natural numbers\<close> 
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theory Nat 
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imports Inductive Typedef Fun Rings 
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begin 
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named_theorems arith "arith facts  only ground formulas" 
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ML_file "Tools/arith_data.ML" 
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subsection \<open>Type \<open>ind\<close>\<close> 
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typedecl ind 

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axiomatization Zero_Rep :: ind and Suc_Rep :: "ind \<Rightarrow> ind" 
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\<comment> \<open>The axiom of infinity in 2 parts:\<close> 

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where Suc_Rep_inject: "Suc_Rep x = Suc_Rep y \<Longrightarrow> x = y" 
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and Suc_Rep_not_Zero_Rep: "Suc_Rep x \<noteq> Zero_Rep" 

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subsection \<open>Type nat\<close> 
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text \<open>Type definition\<close> 

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inductive Nat :: "ind \<Rightarrow> bool" 
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where 

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Zero_RepI: "Nat Zero_Rep" 

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 Suc_RepI: "Nat i \<Longrightarrow> Nat (Suc_Rep i)" 

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typedef nat = "{n. Nat n}" 
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morphisms Rep_Nat Abs_Nat 
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using Nat.Zero_RepI by auto 
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lemma Nat_Rep_Nat: "Nat (Rep_Nat n)" 
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using Rep_Nat by simp 
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lemma Nat_Abs_Nat_inverse: "Nat n \<Longrightarrow> Rep_Nat (Abs_Nat n) = n" 
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using Abs_Nat_inverse by simp 
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lemma Nat_Abs_Nat_inject: "Nat n \<Longrightarrow> Nat m \<Longrightarrow> Abs_Nat n = Abs_Nat m \<longleftrightarrow> n = m" 
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using Abs_Nat_inject by simp 
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instantiation nat :: zero 
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begin 

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definition Zero_nat_def: "0 = Abs_Nat Zero_Rep" 
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instance .. 

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end 

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definition Suc :: "nat \<Rightarrow> nat" 
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where "Suc n = Abs_Nat (Suc_Rep (Rep_Nat n))" 

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lemma Suc_not_Zero: "Suc m \<noteq> 0" 
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by (simp add: Zero_nat_def Suc_def Suc_RepI Zero_RepI 
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Nat_Abs_Nat_inject Suc_Rep_not_Zero_Rep Nat_Rep_Nat) 

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lemma Zero_not_Suc: "0 \<noteq> Suc m" 
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by (rule not_sym) (rule Suc_not_Zero) 
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lemma Suc_Rep_inject': "Suc_Rep x = Suc_Rep y \<longleftrightarrow> x = y" 
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by (rule iffI, rule Suc_Rep_inject) simp_all 
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lemma nat_induct0: 
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assumes "P 0" 
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and "\<And>n. P n \<Longrightarrow> P (Suc n)" 

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shows "P n" 
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using assms 
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apply (unfold Zero_nat_def Suc_def) 

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apply (rule Rep_Nat_inverse [THEN subst]) \<comment> \<open>types force good instantiation\<close> 

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apply (erule Nat_Rep_Nat [THEN Nat.induct]) 

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apply (iprover elim: Nat_Abs_Nat_inverse [THEN subst]) 

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done 

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free_constructors case_nat for "0 :: nat"  Suc pred 

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where "pred (0 :: nat) = (0 :: nat)" 

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apply atomize_elim 
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apply (rename_tac n, induct_tac n rule: nat_induct0, auto) 
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apply (simp add: Suc_def Nat_Abs_Nat_inject Nat_Rep_Nat Suc_RepI Suc_Rep_inject' Rep_Nat_inject) 
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apply (simp only: Suc_not_Zero) 
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done 
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\<comment> \<open>Avoid name clashes by prefixing the output of \<open>old_rep_datatype\<close> with \<open>old\<close>.\<close> 
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setup \<open>Sign.mandatory_path "old"\<close> 
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old_rep_datatype "0 :: nat" Suc 
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apply (erule nat_induct0) 
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apply assumption 

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apply (rule nat.inject) 

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apply (rule nat.distinct(1)) 

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done 

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setup \<open>Sign.parent_path\<close> 
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\<comment> \<open>But erase the prefix for properties that are not generated by \<open>free_constructors\<close>.\<close> 
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setup \<open>Sign.mandatory_path "nat"\<close> 
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declare old.nat.inject[iff del] 
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and old.nat.distinct(1)[simp del, induct_simp del] 

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lemmas induct = old.nat.induct 
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lemmas inducts = old.nat.inducts 
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lemmas rec = old.nat.rec 
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lemmas simps = nat.inject nat.distinct nat.case nat.rec 
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setup \<open>Sign.parent_path\<close> 
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abbreviation rec_nat :: "'a \<Rightarrow> (nat \<Rightarrow> 'a \<Rightarrow> 'a) \<Rightarrow> nat \<Rightarrow> 'a" 
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where "rec_nat \<equiv> old.rec_nat" 

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declare nat.sel[code del] 
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hide_const (open) Nat.pred \<comment> \<open>hide everything related to the selector\<close> 
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hide_fact 
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nat.case_eq_if 
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nat.collapse 
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nat.expand 
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nat.sel 
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nat.exhaust_sel 
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nat.split_sel 
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nat.split_sel_asm 
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lemma nat_exhaust [case_names 0 Suc, cases type: nat]: 
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"(y = 0 \<Longrightarrow> P) \<Longrightarrow> (\<And>nat. y = Suc nat \<Longrightarrow> P) \<Longrightarrow> P" 
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\<comment> \<open>for backward compatibility  names of variables differ\<close> 
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by (rule old.nat.exhaust) 
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lemma nat_induct [case_names 0 Suc, induct type: nat]: 
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fixes n 
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assumes "P 0" and "\<And>n. P n \<Longrightarrow> P (Suc n)" 
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shows "P n" 
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\<comment> \<open>for backward compatibility  names of variables differ\<close> 
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using assms by (rule nat.induct) 

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hide_fact 
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nat_exhaust 
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nat_induct0 
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ML \<open> 
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val nat_basic_lfp_sugar = 
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let 

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val ctr_sugar = the (Ctr_Sugar.ctr_sugar_of_global @{theory} @{type_name nat}); 

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val recx = Logic.varify_types_global @{term rec_nat}; 

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val C = body_type (fastype_of recx); 

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in 

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{T = HOLogic.natT, fp_res_index = 0, C = C, fun_arg_Tsss = [[], [[HOLogic.natT, C]]], 

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ctr_sugar = ctr_sugar, recx = recx, rec_thms = @{thms nat.rec}} 

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end; 

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\<close> 
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setup \<open> 

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let 
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fun basic_lfp_sugars_of _ [@{typ nat}] _ _ ctxt = 

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([], [0], [nat_basic_lfp_sugar], [], [], [], TrueI (*dummy*), [], false, ctxt) 
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 basic_lfp_sugars_of bs arg_Ts callers callssss ctxt = 
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BNF_LFP_Rec_Sugar.default_basic_lfp_sugars_of bs arg_Ts callers callssss ctxt; 

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in 

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BNF_LFP_Rec_Sugar.register_lfp_rec_extension 

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{nested_simps = [], is_new_datatype = K (K true), basic_lfp_sugars_of = basic_lfp_sugars_of, 

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rewrite_nested_rec_call = NONE} 

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end 

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\<close> 
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text \<open>Injectiveness and distinctness lemmas\<close> 

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lemma inj_Suc[simp]: "inj_on Suc N" 
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by (simp add: inj_on_def) 
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lemma Suc_neq_Zero: "Suc m = 0 \<Longrightarrow> R" 
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by (rule notE) (rule Suc_not_Zero) 
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lemma Zero_neq_Suc: "0 = Suc m \<Longrightarrow> R" 
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by (rule Suc_neq_Zero) (erule sym) 
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lemma Suc_inject: "Suc x = Suc y \<Longrightarrow> x = y" 
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by (rule inj_Suc [THEN injD]) 
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lemma n_not_Suc_n: "n \<noteq> Suc n" 
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by (induct n) simp_all 
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lemma Suc_n_not_n: "Suc n \<noteq> n" 
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by (rule not_sym) (rule n_not_Suc_n) 
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text \<open>A special form of induction for reasoning about @{term "m < n"} and @{term "m  n"}.\<close> 

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lemma diff_induct: 
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assumes "\<And>x. P x 0" 

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and "\<And>y. P 0 (Suc y)" 

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and "\<And>x y. P x y \<Longrightarrow> P (Suc x) (Suc y)" 

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shows "P m n" 

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proof (induct n arbitrary: m) 
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case 0 

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show ?case by (rule assms(1)) 

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next 

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case (Suc n) 

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show ?case 

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proof (induct m) 

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case 0 

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show ?case by (rule assms(2)) 

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next 

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case (Suc m) 

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from \<open>P m n\<close> show ?case by (rule assms(3)) 

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qed 

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qed 

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subsection \<open>Arithmetic operators\<close> 
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instantiation nat :: comm_monoid_diff 
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begin 
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primrec plus_nat 
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where 

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add_0: "0 + n = (n::nat)" 

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 add_Suc: "Suc m + n = Suc (m + n)" 

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lemma add_0_right [simp]: "m + 0 = m" 

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for m :: nat 

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by (induct m) simp_all 
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lemma add_Suc_right [simp]: "m + Suc n = Suc (m + n)" 
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by (induct m) simp_all 
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declare add_0 [code] 
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lemma add_Suc_shift [code]: "Suc m + n = m + Suc n" 
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by simp 
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primrec minus_nat 
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where 

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diff_0 [code]: "m  0 = (m::nat)" 

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 diff_Suc: "m  Suc n = (case m  n of 0 \<Rightarrow> 0  Suc k \<Rightarrow> k)" 

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28514  243 
declare diff_Suc [simp del] 
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lemma diff_0_eq_0 [simp, code]: "0  n = 0" 
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for n :: nat 

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by (induct n) (simp_all add: diff_Suc) 
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lemma diff_Suc_Suc [simp, code]: "Suc m  Suc n = m  n" 
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by (induct n) (simp_all add: diff_Suc) 
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instance 
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proof 

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fix n m q :: nat 
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show "(n + m) + q = n + (m + q)" by (induct n) simp_all 
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show "n + m = m + n" by (induct n) simp_all 
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show "m + n  m = n" by (induct m) simp_all 
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show "n  m  q = n  (m + q)" by (induct q) (simp_all add: diff_Suc) 
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259 
show "0 + n = n" by simp 
49388  260 
show "0  n = 0" by simp 
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261 
qed 
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262 

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263 
end 
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264 

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265 
hide_fact (open) add_0 add_0_right diff_0 
35047
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266 

26072
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267 
instantiation nat :: comm_semiring_1_cancel 
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268 
begin 
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269 

63588  270 
definition One_nat_def [simp]: "1 = Suc 0" 
271 

272 
primrec times_nat 

273 
where 

274 
mult_0: "0 * n = (0::nat)" 

275 
 mult_Suc: "Suc m * n = n + (m * n)" 

276 

277 
lemma mult_0_right [simp]: "m * 0 = 0" 

278 
for m :: nat 

26072
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279 
by (induct m) simp_all 
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280 

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281 
lemma mult_Suc_right [simp]: "m * Suc n = m + (m * n)" 
57512
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282 
by (induct m) (simp_all add: add.left_commute) 
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283 

63588  284 
lemma add_mult_distrib: "(m + n) * k = (m * k) + (n * k)" 
285 
for m n k :: nat 

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286 
by (induct m) (simp_all add: add.assoc) 
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287 

63110  288 
instance 
289 
proof 

290 
fix k n m q :: nat 

63588  291 
show "0 \<noteq> (1::nat)" 
292 
by simp 

293 
show "1 * n = n" 

294 
by simp 

295 
show "n * m = m * n" 

296 
by (induct n) simp_all 

297 
show "(n * m) * q = n * (m * q)" 

298 
by (induct n) (simp_all add: add_mult_distrib) 

299 
show "(n + m) * q = n * q + m * q" 

300 
by (rule add_mult_distrib) 

63110  301 
show "k * (m  n) = (k * m)  (k * n)" 
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302 
by (induct m n rule: diff_induct) simp_all 
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303 
qed 
25571
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instantiation target rather than legacy instance
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304 

c9e39eafc7a0
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305 
end 
24995  306 

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307 

60758  308 
subsubsection \<open>Addition\<close> 
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309 

61799  310 
text \<open>Reasoning about \<open>m + 0 = 0\<close>, etc.\<close> 
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311 

63588  312 
lemma add_is_0 [iff]: "m + n = 0 \<longleftrightarrow> m = 0 \<and> n = 0" 
313 
for m n :: nat 

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314 
by (cases m) simp_all 
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315 

63110  316 
lemma add_is_1: "m + n = Suc 0 \<longleftrightarrow> m = Suc 0 \<and> n = 0  m = 0 \<and> n = Suc 0" 
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317 
by (cases m) simp_all 
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318 

63110  319 
lemma one_is_add: "Suc 0 = m + n \<longleftrightarrow> m = Suc 0 \<and> n = 0  m = 0 \<and> n = Suc 0" 
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320 
by (rule trans, rule eq_commute, rule add_is_1) 
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321 

63588  322 
lemma add_eq_self_zero: "m + n = m \<Longrightarrow> n = 0" 
323 
for m n :: nat 

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324 
by (induct m) simp_all 
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325 

63588  326 
lemma inj_on_add_nat [simp]: "inj_on (\<lambda>n. n + k) N" 
327 
for k :: nat 

328 
proof (induct k) 

329 
case 0 

330 
then show ?case by simp 

331 
next 

332 
case (Suc k) 

333 
show ?case 

334 
using comp_inj_on [OF Suc inj_Suc] by (simp add: o_def) 

335 
qed 

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336 

47208  337 
lemma Suc_eq_plus1: "Suc n = n + 1" 
63588  338 
by simp 
47208  339 

340 
lemma Suc_eq_plus1_left: "Suc n = 1 + n" 

63588  341 
by simp 
47208  342 

26072
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343 

60758  344 
subsubsection \<open>Difference\<close> 
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345 

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346 
lemma Suc_diff_diff [simp]: "(Suc m  n)  Suc k = m  n  k" 
62365  347 
by (simp add: diff_diff_add) 
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348 

30093  349 
lemma diff_Suc_1 [simp]: "Suc n  1 = n" 
63588  350 
by simp 
351 

30093  352 

60758  353 
subsubsection \<open>Multiplication\<close> 
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354 

63110  355 
lemma mult_is_0 [simp]: "m * n = 0 \<longleftrightarrow> m = 0 \<or> n = 0" for m n :: nat 
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356 
by (induct m) auto 
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357 

63110  358 
lemma mult_eq_1_iff [simp]: "m * n = Suc 0 \<longleftrightarrow> m = Suc 0 \<and> n = Suc 0" 
63588  359 
proof (induct m) 
360 
case 0 

361 
then show ?case by simp 

362 
next 

363 
case (Suc m) 

364 
then show ?case by (induct n) auto 

365 
qed 

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366 

63110  367 
lemma one_eq_mult_iff [simp]: "Suc 0 = m * n \<longleftrightarrow> m = Suc 0 \<and> n = Suc 0" 
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368 
apply (rule trans) 
63588  369 
apply (rule_tac [2] mult_eq_1_iff) 
370 
apply fastforce 

26072
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371 
done 
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372 

63588  373 
lemma nat_mult_eq_1_iff [simp]: "m * n = 1 \<longleftrightarrow> m = 1 \<and> n = 1" 
374 
for m n :: nat 

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375 
unfolding One_nat_def by (rule mult_eq_1_iff) 
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376 

63588  377 
lemma nat_1_eq_mult_iff [simp]: "1 = m * n \<longleftrightarrow> m = 1 \<and> n = 1" 
378 
for m n :: nat 

30079
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changeset

379 
unfolding One_nat_def by (rule one_eq_mult_iff) 
293b896b9c25
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changeset

380 

63588  381 
lemma mult_cancel1 [simp]: "k * m = k * n \<longleftrightarrow> m = n \<or> k = 0" 
382 
for k m n :: nat 

26072
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383 
proof  
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384 
have "k \<noteq> 0 \<Longrightarrow> k * m = k * n \<Longrightarrow> m = n" 
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385 
proof (induct n arbitrary: m) 
63110  386 
case 0 
387 
then show "m = 0" by simp 

26072
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388 
next 
63110  389 
case (Suc n) 
390 
then show "m = Suc n" 

391 
by (cases m) (simp_all add: eq_commute [of 0]) 

26072
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392 
qed 
f65a7fa2da6c
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changeset

393 
then show ?thesis by auto 
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394 
qed 
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395 

63588  396 
lemma mult_cancel2 [simp]: "m * k = n * k \<longleftrightarrow> m = n \<or> k = 0" 
397 
for k m n :: nat 

57512
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parents:
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398 
by (simp add: mult.commute) 
26072
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changeset

399 

63110  400 
lemma Suc_mult_cancel1: "Suc k * m = Suc k * n \<longleftrightarrow> m = n" 
26072
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parents:
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401 
by (subst mult_cancel1) simp 
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changeset

402 

24995  403 

60758  404 
subsection \<open>Orders on @{typ nat}\<close> 
405 

406 
subsubsection \<open>Operation definition\<close> 

24995  407 

26072
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408 
instantiation nat :: linorder 
25510  409 
begin 
410 

63588  411 
primrec less_eq_nat 
412 
where 

413 
"(0::nat) \<le> n \<longleftrightarrow> True" 

414 
 "Suc m \<le> n \<longleftrightarrow> (case n of 0 \<Rightarrow> False  Suc n \<Rightarrow> m \<le> n)" 

26072
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415 

28514  416 
declare less_eq_nat.simps [simp del] 
63110  417 

63588  418 
lemma le0 [iff]: "0 \<le> n" for 
419 
n :: nat 

63110  420 
by (simp add: less_eq_nat.simps) 
421 

63588  422 
lemma [code]: "0 \<le> n \<longleftrightarrow> True" 
423 
for n :: nat 

63110  424 
by simp 
26072
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425 

63588  426 
definition less_nat 
427 
where less_eq_Suc_le: "n < m \<longleftrightarrow> Suc n \<le> m" 

26072
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parents:
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428 

f65a7fa2da6c
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changeset

429 
lemma Suc_le_mono [iff]: "Suc n \<le> Suc m \<longleftrightarrow> n \<le> m" 
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changeset

430 
by (simp add: less_eq_nat.simps(2)) 
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parents:
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changeset

431 

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parents:
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changeset

432 
lemma Suc_le_eq [code]: "Suc m \<le> n \<longleftrightarrow> m < n" 
f65a7fa2da6c
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parents:
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diff
changeset

433 
unfolding less_eq_Suc_le .. 
f65a7fa2da6c
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parents:
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diff
changeset

434 

63588  435 
lemma le_0_eq [iff]: "n \<le> 0 \<longleftrightarrow> n = 0" 
436 
for n :: nat 

26072
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parents:
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changeset

437 
by (induct n) (simp_all add: less_eq_nat.simps(2)) 
f65a7fa2da6c
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haftmann
parents:
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438 

63588  439 
lemma not_less0 [iff]: "\<not> n < 0" 
440 
for n :: nat 

26072
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parents:
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diff
changeset

441 
by (simp add: less_eq_Suc_le) 
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parents:
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diff
changeset

442 

63588  443 
lemma less_nat_zero_code [code]: "n < 0 \<longleftrightarrow> False" 
444 
for n :: nat 

26072
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parents:
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changeset

445 
by simp 
f65a7fa2da6c
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parents:
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changeset

446 

f65a7fa2da6c
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parents:
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diff
changeset

447 
lemma Suc_less_eq [iff]: "Suc m < Suc n \<longleftrightarrow> m < n" 
f65a7fa2da6c
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parents:
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changeset

448 
by (simp add: less_eq_Suc_le) 
f65a7fa2da6c
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parents:
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diff
changeset

449 

f65a7fa2da6c
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parents:
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diff
changeset

450 
lemma less_Suc_eq_le [code]: "m < Suc n \<longleftrightarrow> m \<le> n" 
f65a7fa2da6c
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parents:
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diff
changeset

451 
by (simp add: less_eq_Suc_le) 
f65a7fa2da6c
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parents:
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diff
changeset

452 

56194  453 
lemma Suc_less_eq2: "Suc n < m \<longleftrightarrow> (\<exists>m'. m = Suc m' \<and> n < m')" 
454 
by (cases m) auto 

455 

26072
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haftmann
parents:
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diff
changeset

456 
lemma le_SucI: "m \<le> n \<Longrightarrow> m \<le> Suc n" 
63110  457 
by (induct m arbitrary: n) (simp_all add: less_eq_nat.simps(2) split: nat.splits) 
26072
f65a7fa2da6c
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haftmann
parents:
25928
diff
changeset

458 

f65a7fa2da6c
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haftmann
parents:
25928
diff
changeset

459 
lemma Suc_leD: "Suc m \<le> n \<Longrightarrow> m \<le> n" 
f65a7fa2da6c
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haftmann
parents:
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diff
changeset

460 
by (cases n) (auto intro: le_SucI) 
f65a7fa2da6c
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haftmann
parents:
25928
diff
changeset

461 

f65a7fa2da6c
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haftmann
parents:
25928
diff
changeset

462 
lemma less_SucI: "m < n \<Longrightarrow> m < Suc n" 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

463 
by (simp add: less_eq_Suc_le) (erule Suc_leD) 
24995  464 

26072
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haftmann
parents:
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diff
changeset

465 
lemma Suc_lessD: "Suc m < n \<Longrightarrow> m < n" 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
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diff
changeset

466 
by (simp add: less_eq_Suc_le) (erule Suc_leD) 
25510  467 

26315
cb3badaa192e
removed redundant less_trans, less_linear, le_imp_less_or_eq, le_less_trans, less_le_trans (cf. Orderings.thy);
wenzelm
parents:
26300
diff
changeset

468 
instance 
cb3badaa192e
removed redundant less_trans, less_linear, le_imp_less_or_eq, le_less_trans, less_le_trans (cf. Orderings.thy);
wenzelm
parents:
26300
diff
changeset

469 
proof 
63110  470 
fix n m q :: nat 
60562
24af00b010cf
Amalgamation of the class comm_semiring_1_diff_distrib into comm_semiring_1_cancel. Moving axiom le_add_diff_inverse2 from semiring_numeral_div to linordered_semidom.
paulson <lp15@cam.ac.uk>
parents:
60427
diff
changeset

471 
show "n < m \<longleftrightarrow> n \<le> m \<and> \<not> m \<le> n" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

472 
proof (induct n arbitrary: m) 
63110  473 
case 0 
63588  474 
then show ?case 
475 
by (cases m) (simp_all add: less_eq_Suc_le) 

26072
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haftmann
parents:
25928
diff
changeset

476 
next 
63110  477 
case (Suc n) 
63588  478 
then show ?case 
479 
by (cases m) (simp_all add: less_eq_Suc_le) 

26072
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haftmann
parents:
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diff
changeset

480 
qed 
63588  481 
show "n \<le> n" 
482 
by (induct n) simp_all 

63110  483 
then show "n = m" if "n \<le> m" and "m \<le> n" 
484 
using that by (induct n arbitrary: m) 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

485 
(simp_all add: less_eq_nat.simps(2) split: nat.splits) 
63110  486 
show "n \<le> q" if "n \<le> m" and "m \<le> q" 
487 
using that 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

488 
proof (induct n arbitrary: m q) 
63110  489 
case 0 
490 
show ?case by simp 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

491 
next 
63110  492 
case (Suc n) 
493 
then show ?case 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

494 
by (simp_all (no_asm_use) add: less_eq_nat.simps(2) split: nat.splits, clarify, 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

495 
simp_all (no_asm_use) add: less_eq_nat.simps(2) split: nat.splits, clarify, 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

496 
simp_all (no_asm_use) add: less_eq_nat.simps(2) split: nat.splits) 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

497 
qed 
63110  498 
show "n \<le> m \<or> m \<le> n" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

499 
by (induct n arbitrary: m) 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

500 
(simp_all add: less_eq_nat.simps(2) split: nat.splits) 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

501 
qed 
25510  502 

503 
end 

13449  504 

52729
412c9e0381a1
factored syntactic type classes for bot and top (by Alessandro Coglio)
haftmann
parents:
52435
diff
changeset

505 
instantiation nat :: order_bot 
29652  506 
begin 
507 

63588  508 
definition bot_nat :: nat 
509 
where "bot_nat = 0" 

510 

511 
instance 

512 
by standard (simp add: bot_nat_def) 

29652  513 

514 
end 

515 

51329
4a3c453f99a1
split dense into inner_dense_order and no_top/no_bot
hoelzl
parents:
51263
diff
changeset

516 
instance nat :: no_top 
61169  517 
by standard (auto intro: less_Suc_eq_le [THEN iffD2]) 
52289  518 

51329
4a3c453f99a1
split dense into inner_dense_order and no_top/no_bot
hoelzl
parents:
51263
diff
changeset

519 

60758  520 
subsubsection \<open>Introduction properties\<close> 
13449  521 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

522 
lemma lessI [iff]: "n < Suc n" 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

523 
by (simp add: less_Suc_eq_le) 
13449  524 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

525 
lemma zero_less_Suc [iff]: "0 < Suc n" 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

526 
by (simp add: less_Suc_eq_le) 
13449  527 

528 

60758  529 
subsubsection \<open>Elimination properties\<close> 
13449  530 

63588  531 
lemma less_not_refl: "\<not> n < n" 
532 
for n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

533 
by (rule order_less_irrefl) 
13449  534 

63588  535 
lemma less_not_refl2: "n < m \<Longrightarrow> m \<noteq> n" 
536 
for m n :: nat 

60562
24af00b010cf
Amalgamation of the class comm_semiring_1_diff_distrib into comm_semiring_1_cancel. Moving axiom le_add_diff_inverse2 from semiring_numeral_div to linordered_semidom.
paulson <lp15@cam.ac.uk>
parents:
60427
diff
changeset

537 
by (rule not_sym) (rule less_imp_neq) 
13449  538 

63588  539 
lemma less_not_refl3: "s < t \<Longrightarrow> s \<noteq> t" 
540 
for s t :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

541 
by (rule less_imp_neq) 
13449  542 

63588  543 
lemma less_irrefl_nat: "n < n \<Longrightarrow> R" 
544 
for n :: nat 

26335
961bbcc9d85b
removed redundant Nat.less_not_sym, Nat.less_asym;
wenzelm
parents:
26315
diff
changeset

545 
by (rule notE, rule less_not_refl) 
13449  546 

63588  547 
lemma less_zeroE: "n < 0 \<Longrightarrow> R" 
548 
for n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

549 
by (rule notE) (rule not_less0) 
13449  550 

63110  551 
lemma less_Suc_eq: "m < Suc n \<longleftrightarrow> m < n \<or> m = n" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

552 
unfolding less_Suc_eq_le le_less .. 
13449  553 

30079
293b896b9c25
make proofs work whether or not One_nat_def is a simp rule; replace 1 with Suc 0 in the rhs of some simp rules
huffman
parents:
30056
diff
changeset

554 
lemma less_Suc0 [iff]: "(n < Suc 0) = (n = 0)" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

555 
by (simp add: less_Suc_eq) 
13449  556 

63588  557 
lemma less_one [iff]: "n < 1 \<longleftrightarrow> n = 0" 
558 
for n :: nat 

30079
293b896b9c25
make proofs work whether or not One_nat_def is a simp rule; replace 1 with Suc 0 in the rhs of some simp rules
huffman
parents:
30056
diff
changeset

559 
unfolding One_nat_def by (rule less_Suc0) 
13449  560 

63110  561 
lemma Suc_mono: "m < n \<Longrightarrow> Suc m < Suc n" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

562 
by simp 
13449  563 

63588  564 
text \<open>"Less than" is antisymmetric, sort of.\<close> 
565 
lemma less_antisym: "\<not> n < m \<Longrightarrow> n < Suc m \<Longrightarrow> m = n" 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

566 
unfolding not_less less_Suc_eq_le by (rule antisym) 
14302  567 

63588  568 
lemma nat_neq_iff: "m \<noteq> n \<longleftrightarrow> m < n \<or> n < m" 
569 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

570 
by (rule linorder_neq_iff) 
13449  571 

572 

60758  573 
subsubsection \<open>Inductive (?) properties\<close> 
13449  574 

63110  575 
lemma Suc_lessI: "m < n \<Longrightarrow> Suc m \<noteq> n \<Longrightarrow> Suc m < n" 
60562
24af00b010cf
Amalgamation of the class comm_semiring_1_diff_distrib into comm_semiring_1_cancel. Moving axiom le_add_diff_inverse2 from semiring_numeral_div to linordered_semidom.
paulson <lp15@cam.ac.uk>
parents:
60427
diff
changeset

576 
unfolding less_eq_Suc_le [of m] le_less by simp 
13449  577 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

578 
lemma lessE: 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

579 
assumes major: "i < k" 
63110  580 
and 1: "k = Suc i \<Longrightarrow> P" 
581 
and 2: "\<And>j. i < j \<Longrightarrow> k = Suc j \<Longrightarrow> P" 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

582 
shows P 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

583 
proof  
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

584 
from major have "\<exists>j. i \<le> j \<and> k = Suc j" 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

585 
unfolding less_eq_Suc_le by (induct k) simp_all 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

586 
then have "(\<exists>j. i < j \<and> k = Suc j) \<or> k = Suc i" 
63110  587 
by (auto simp add: less_le) 
588 
with 1 2 show P by auto 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

589 
qed 
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

590 

63110  591 
lemma less_SucE: 
592 
assumes major: "m < Suc n" 

593 
and less: "m < n \<Longrightarrow> P" 

594 
and eq: "m = n \<Longrightarrow> P" 

595 
shows P 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

596 
apply (rule major [THEN lessE]) 
63588  597 
apply (rule eq) 
598 
apply blast 

599 
apply (rule less) 

600 
apply blast 

13449  601 
done 
602 

63110  603 
lemma Suc_lessE: 
604 
assumes major: "Suc i < k" 

605 
and minor: "\<And>j. i < j \<Longrightarrow> k = Suc j \<Longrightarrow> P" 

606 
shows P 

13449  607 
apply (rule major [THEN lessE]) 
63588  608 
apply (erule lessI [THEN minor]) 
609 
apply (erule Suc_lessD [THEN minor]) 

610 
apply assumption 

13449  611 
done 
612 

63110  613 
lemma Suc_less_SucD: "Suc m < Suc n \<Longrightarrow> m < n" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

614 
by simp 
13449  615 

616 
lemma less_trans_Suc: 

63110  617 
assumes le: "i < j" 
618 
shows "j < k \<Longrightarrow> Suc i < k" 

63588  619 
proof (induct k) 
620 
case 0 

621 
then show ?case by simp 

622 
next 

623 
case (Suc k) 

624 
with le show ?case 

625 
by simp (auto simp add: less_Suc_eq dest: Suc_lessD) 

626 
qed 

627 

628 
text \<open>Can be used with \<open>less_Suc_eq\<close> to get @{prop "n = m \<or> n < m"}.\<close> 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

629 
lemma not_less_eq: "\<not> m < n \<longleftrightarrow> n < Suc m" 
63588  630 
by (simp only: not_less less_Suc_eq_le) 
13449  631 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

632 
lemma not_less_eq_eq: "\<not> m \<le> n \<longleftrightarrow> Suc n \<le> m" 
63588  633 
by (simp only: not_le Suc_le_eq) 
634 

635 
text \<open>Properties of "less than or equal".\<close> 

13449  636 

63110  637 
lemma le_imp_less_Suc: "m \<le> n \<Longrightarrow> m < Suc n" 
63588  638 
by (simp only: less_Suc_eq_le) 
13449  639 

63110  640 
lemma Suc_n_not_le_n: "\<not> Suc n \<le> n" 
63588  641 
by (simp add: not_le less_Suc_eq_le) 
642 

643 
lemma le_Suc_eq: "m \<le> Suc n \<longleftrightarrow> m \<le> n \<or> m = Suc n" 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

644 
by (simp add: less_Suc_eq_le [symmetric] less_Suc_eq) 
13449  645 

63110  646 
lemma le_SucE: "m \<le> Suc n \<Longrightarrow> (m \<le> n \<Longrightarrow> R) \<Longrightarrow> (m = Suc n \<Longrightarrow> R) \<Longrightarrow> R" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

647 
by (drule le_Suc_eq [THEN iffD1], iprover+) 
13449  648 

63588  649 
lemma Suc_leI: "m < n \<Longrightarrow> Suc m \<le> n" 
650 
by (simp only: Suc_le_eq) 

651 

652 
text \<open>Stronger version of \<open>Suc_leD\<close>.\<close> 

63110  653 
lemma Suc_le_lessD: "Suc m \<le> n \<Longrightarrow> m < n" 
63588  654 
by (simp only: Suc_le_eq) 
13449  655 

63110  656 
lemma less_imp_le_nat: "m < n \<Longrightarrow> m \<le> n" for m n :: nat 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

657 
unfolding less_eq_Suc_le by (rule Suc_leD) 
13449  658 

61799  659 
text \<open>For instance, \<open>(Suc m < Suc n) = (Suc m \<le> n) = (m < n)\<close>\<close> 
26315
cb3badaa192e
removed redundant less_trans, less_linear, le_imp_less_or_eq, le_less_trans, less_le_trans (cf. Orderings.thy);
wenzelm
parents:
26300
diff
changeset

660 
lemmas le_simps = less_imp_le_nat less_Suc_eq_le Suc_le_eq 
13449  661 

662 

63110  663 
text \<open>Equivalence of \<open>m \<le> n\<close> and \<open>m < n \<or> m = n\<close>\<close> 
664 

63588  665 
lemma less_or_eq_imp_le: "m < n \<or> m = n \<Longrightarrow> m \<le> n" 
666 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

667 
unfolding le_less . 
13449  668 

63588  669 
lemma le_eq_less_or_eq: "m \<le> n \<longleftrightarrow> m < n \<or> m = n" 
670 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

671 
by (rule le_less) 
13449  672 

61799  673 
text \<open>Useful with \<open>blast\<close>.\<close> 
63588  674 
lemma eq_imp_le: "m = n \<Longrightarrow> m \<le> n" 
675 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

676 
by auto 
13449  677 

63588  678 
lemma le_refl: "n \<le> n" 
679 
for n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

680 
by simp 
13449  681 

63588  682 
lemma le_trans: "i \<le> j \<Longrightarrow> j \<le> k \<Longrightarrow> i \<le> k" 
683 
for i j k :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

684 
by (rule order_trans) 
13449  685 

63588  686 
lemma le_antisym: "m \<le> n \<Longrightarrow> n \<le> m \<Longrightarrow> m = n" 
687 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

688 
by (rule antisym) 
13449  689 

63588  690 
lemma nat_less_le: "m < n \<longleftrightarrow> m \<le> n \<and> m \<noteq> n" 
691 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

692 
by (rule less_le) 
13449  693 

63588  694 
lemma le_neq_implies_less: "m \<le> n \<Longrightarrow> m \<noteq> n \<Longrightarrow> m < n" 
695 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

696 
unfolding less_le .. 
13449  697 

63588  698 
lemma nat_le_linear: "m \<le> n  n \<le> m" 
699 
for m n :: nat 

26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

700 
by (rule linear) 
14341
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

701 

22718  702 
lemmas linorder_neqE_nat = linorder_neqE [where 'a = nat] 
15921  703 

63110  704 
lemma le_less_Suc_eq: "m \<le> n \<Longrightarrow> n < Suc m \<longleftrightarrow> n = m" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

705 
unfolding less_Suc_eq_le by auto 
13449  706 

63110  707 
lemma not_less_less_Suc_eq: "\<not> n < m \<Longrightarrow> n < Suc m \<longleftrightarrow> n = m" 
26072
f65a7fa2da6c
<= and < on nat no longer depend on wellfounded relations
haftmann
parents:
25928
diff
changeset

708 
unfolding not_less by (rule le_less_Suc_eq) 
13449  709 

710 
lemmas not_less_simps = not_less_less_Suc_eq le_less_Suc_eq 

711 

63110  712 
lemma not0_implies_Suc: "n \<noteq> 0 \<Longrightarrow> \<exists>m. n = Suc m" 
713 
by (cases n) simp_all 

714 

715 
lemma gr0_implies_Suc: "n > 0 \<Longrightarrow> \<exists>m. n = Suc m" 

716 
by (cases n) simp_all 

717 

63588  718 
lemma gr_implies_not0: "m < n \<Longrightarrow> n \<noteq> 0" 
719 
for m n :: nat 

63110  720 
by (cases n) simp_all 
721 

63588  722 
lemma neq0_conv[iff]: "n \<noteq> 0 \<longleftrightarrow> 0 < n" 
723 
for n :: nat 

63110  724 
by (cases n) simp_all 
25140  725 

61799  726 
text \<open>This theorem is useful with \<open>blast\<close>\<close> 
63588  727 
lemma gr0I: "(n = 0 \<Longrightarrow> False) \<Longrightarrow> 0 < n" 
728 
for n :: nat 

729 
by (rule neq0_conv[THEN iffD1]) iprover 

63110  730 

731 
lemma gr0_conv_Suc: "0 < n \<longleftrightarrow> (\<exists>m. n = Suc m)" 

732 
by (fast intro: not0_implies_Suc) 

733 

63588  734 
lemma not_gr0 [iff]: "\<not> 0 < n \<longleftrightarrow> n = 0" 
735 
for n :: nat 

63110  736 
using neq0_conv by blast 
737 

738 
lemma Suc_le_D: "Suc n \<le> m' \<Longrightarrow> \<exists>m. m' = Suc m" 

739 
by (induct m') simp_all 

13449  740 

60758  741 
text \<open>Useful in certain inductive arguments\<close> 
63110  742 
lemma less_Suc_eq_0_disj: "m < Suc n \<longleftrightarrow> m = 0 \<or> (\<exists>j. m = Suc j \<and> j < n)" 
743 
by (cases m) simp_all 

13449  744 

745 

60758  746 
subsubsection \<open>Monotonicity of Addition\<close> 
13449  747 

63110  748 
lemma Suc_pred [simp]: "n > 0 \<Longrightarrow> Suc (n  Suc 0) = n" 
749 
by (simp add: diff_Suc split: nat.split) 

750 

751 
lemma Suc_diff_1 [simp]: "0 < n \<Longrightarrow> Suc (n  1) = n" 

752 
unfolding One_nat_def by (rule Suc_pred) 

753 

63588  754 
lemma nat_add_left_cancel_le [simp]: "k + m \<le> k + n \<longleftrightarrow> m \<le> n" 
755 
for k m n :: nat 

63110  756 
by (induct k) simp_all 
757 

63588  758 
lemma nat_add_left_cancel_less [simp]: "k + m < k + n \<longleftrightarrow> m < n" 
759 
for k m n :: nat 

63110  760 
by (induct k) simp_all 
761 

63588  762 
lemma add_gr_0 [iff]: "m + n > 0 \<longleftrightarrow> m > 0 \<or> n > 0" 
763 
for m n :: nat 

63110  764 
by (auto dest: gr0_implies_Suc) 
13449  765 

60758  766 
text \<open>strict, in 1st argument\<close> 
63588  767 
lemma add_less_mono1: "i < j \<Longrightarrow> i + k < j + k" 
768 
for i j k :: nat 

63110  769 
by (induct k) simp_all 
14341
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

770 

60758  771 
text \<open>strict, in both arguments\<close> 
63588  772 
lemma add_less_mono: "i < j \<Longrightarrow> k < l \<Longrightarrow> i + k < j + l" 
773 
for i j k l :: nat 

14341
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

774 
apply (rule add_less_mono1 [THEN less_trans], assumption+) 
63588  775 
apply (induct j) 
776 
apply simp_all 

14341
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

777 
done 
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

778 

61799  779 
text \<open>Deleted \<open>less_natE\<close>; use \<open>less_imp_Suc_add RS exE\<close>\<close> 
63110  780 
lemma less_imp_Suc_add: "m < n \<Longrightarrow> \<exists>k. n = Suc (m + k)" 
63588  781 
proof (induct n) 
782 
case 0 

783 
then show ?case by simp 

784 
next 

785 
case Suc 

786 
then show ?case 

787 
by (simp add: order_le_less) 

788 
(blast elim!: less_SucE intro!: Nat.add_0_right [symmetric] add_Suc_right [symmetric]) 

789 
qed 

790 

791 
lemma le_Suc_ex: "k \<le> l \<Longrightarrow> (\<exists>n. l = k + n)" 

792 
for k l :: nat 

56194  793 
by (auto simp: less_Suc_eq_le[symmetric] dest: less_imp_Suc_add) 
794 

61799  795 
text \<open>strict, in 1st argument; proof is by induction on \<open>k > 0\<close>\<close> 
62481
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

796 
lemma mult_less_mono2: 
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

797 
fixes i j :: nat 
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

798 
assumes "i < j" and "0 < k" 
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

799 
shows "k * i < k * j" 
63110  800 
using \<open>0 < k\<close> 
801 
proof (induct k) 

802 
case 0 

803 
then show ?case by simp 

62481
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

804 
next 
63110  805 
case (Suc k) 
806 
with \<open>i < j\<close> show ?case 

62481
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

807 
by (cases k) (simp_all add: add_less_mono) 
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

808 
qed 
14341
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

809 

60758  810 
text \<open>Addition is the inverse of subtraction: 
811 
if @{term "n \<le> m"} then @{term "n + (m  n) = m"}.\<close> 

63588  812 
lemma add_diff_inverse_nat: "\<not> m < n \<Longrightarrow> n + (m  n) = m" 
813 
for m n :: nat 

63110  814 
by (induct m n rule: diff_induct) simp_all 
815 

63588  816 
lemma nat_le_iff_add: "m \<le> n \<longleftrightarrow> (\<exists>k. n = m + k)" 
817 
for m n :: nat 

63110  818 
using nat_add_left_cancel_le[of m 0] by (auto dest: le_Suc_ex) 
62376
85f38d5f8807
Rename ordered_comm_monoid_add to ordered_cancel_comm_monoid_add. Introduce ordreed_comm_monoid_add, canonically_ordered_comm_monoid and dioid. Setup nat, entat and ennreal as dioids.
hoelzl
parents:
62365
diff
changeset

819 

63588  820 
text \<open>The naturals form an ordered \<open>semidom\<close> and a \<open>dioid\<close>.\<close> 
62376
85f38d5f8807
Rename ordered_comm_monoid_add to ordered_cancel_comm_monoid_add. Introduce ordreed_comm_monoid_add, canonically_ordered_comm_monoid and dioid. Setup nat, entat and ennreal as dioids.
hoelzl
parents:
62365
diff
changeset

821 

35028
108662d50512
more consistent naming of type classes involving orderings (and lattices)  c.f. NEWS
haftmann
parents:
34208
diff
changeset

822 
instance nat :: linordered_semidom 
14341
a09441bd4f1e
Ring_and_Field now requires axiom add_left_imp_eq for semirings.
paulson
parents:
14331
diff
changeset

823 
proof 
63110  824 
fix m n q :: nat 
63588  825 
show "0 < (1::nat)" 
826 
by simp 

827 
show "m \<le> n \<Longrightarrow> q + m \<le> q + n" 

828 
by simp 

829 
show "m < n \<Longrightarrow> 0 < q \<Longrightarrow> q * m < q * n" 

830 
by (simp add: mult_less_mono2) 

831 
show "m \<noteq> 0 \<Longrightarrow> n \<noteq> 0 \<Longrightarrow> m * n \<noteq> 0" 

832 
by simp 

63110  833 
show "n \<le> m \<Longrightarrow> (m  n) + n = m" 
60562
24af00b010cf
Amalgamation of the class comm_semiring_1_diff_distrib into comm_semiring_1_cancel. Moving axiom le_add_diff_inverse2 from semiring_numeral_div to linordered_semidom.
paulson <lp15@cam.ac.uk>
parents:
60427
diff
changeset

834 
by (simp add: add_diff_inverse_nat add.commute linorder_not_less) 
62376
85f38d5f8807
Rename ordered_comm_monoid_add to ordered_cancel_comm_monoid_add. Introduce ordreed_comm_monoid_add, canonically_ordered_comm_monoid and dioid. Setup nat, entat and ennreal as dioids.
hoelzl
parents:
62365
diff
changeset

835 
qed 
85f38d5f8807
Rename ordered_comm_monoid_add to ordered_cancel_comm_monoid_add. Introduce ordreed_comm_monoid_add, canonically_ordered_comm_monoid and dioid. Setup nat, entat and ennreal as dioids.
hoelzl
parents:
62365
diff
changeset

836 

85f38d5f8807
Rename ordered_comm_monoid_add to ordered_cancel_comm_monoid_add. Introduce ordreed_comm_monoid_add, canonically_ordered_comm_monoid and dioid. Setup nat, entat and ennreal as dioids.
hoelzl
parents:
62365
diff
changeset

837 
instance nat :: dioid 
63110  838 
by standard (rule nat_le_iff_add) 
63588  839 

63145  840 
declare le0[simp del] \<comment> \<open>This is now @{thm zero_le}\<close> 
841 
declare le_0_eq[simp del] \<comment> \<open>This is now @{thm le_zero_eq}\<close> 

842 
declare not_less0[simp del] \<comment> \<open>This is now @{thm not_less_zero}\<close> 

843 
declare not_gr0[simp del] \<comment> \<open>This is now @{thm not_gr_zero}\<close> 

62376
85f38d5f8807
Rename ordered_comm_monoid_add to ordered_cancel_comm_monoid_add. Introduce ordreed_comm_monoid_add, canonically_ordered_comm_monoid and dioid. Setup nat, entat and ennreal as dioids.
hoelzl
parents:
62365
diff
changeset

844 

63110  845 
instance nat :: ordered_cancel_comm_monoid_add .. 
846 
instance nat :: ordered_cancel_comm_monoid_diff .. 

847 

44817  848 

60758  849 
subsubsection \<open>@{term min} and @{term max}\<close> 
44817  850 

851 
lemma mono_Suc: "mono Suc" 

63110  852 
by (rule monoI) simp 
853 

63588  854 
lemma min_0L [simp]: "min 0 n = 0" 
855 
for n :: nat 

63110  856 
by (rule min_absorb1) simp 
857 

63588  858 
lemma min_0R [simp]: "min n 0 = 0" 
859 
for n :: nat 

63110  860 
by (rule min_absorb2) simp 
44817  861 

862 
lemma min_Suc_Suc [simp]: "min (Suc m) (Suc n) = Suc (min m n)" 

63110  863 
by (simp add: mono_Suc min_of_mono) 
864 

865 
lemma min_Suc1: "min (Suc n) m = (case m of 0 \<Rightarrow> 0  Suc m' \<Rightarrow> Suc(min n m'))" 

866 
by (simp split: nat.split) 

867 

868 
lemma min_Suc2: "min m (Suc n) = (case m of 0 \<Rightarrow> 0  Suc m' \<Rightarrow> Suc(min m' n))" 

869 
by (simp split: nat.split) 

870 

63588  871 
lemma max_0L [simp]: "max 0 n = n" 
872 
for n :: nat 

63110  873 
by (rule max_absorb2) simp 
874 

63588  875 
lemma max_0R [simp]: "max n 0 = n" 
876 
for n :: nat 

63110  877 
by (rule max_absorb1) simp 
878 

879 
lemma max_Suc_Suc [simp]: "max (Suc m) (Suc n) = Suc (max m n)" 

880 
by (simp add: mono_Suc max_of_mono) 

881 

882 
lemma max_Suc1: "max (Suc n) m = (case m of 0 \<Rightarrow> Suc n  Suc m' \<Rightarrow> Suc (max n m'))" 

883 
by (simp split: nat.split) 

884 

885 
lemma max_Suc2: "max m (Suc n) = (case m of 0 \<Rightarrow> Suc n  Suc m' \<Rightarrow> Suc (max m' n))" 

886 
by (simp split: nat.split) 

887 

63588  888 
lemma nat_mult_min_left: "min m n * q = min (m * q) (n * q)" 
889 
for m n q :: nat 

63110  890 
by (simp add: min_def not_le) 
891 
(auto dest: mult_right_le_imp_le mult_right_less_imp_less le_less_trans) 

892 

63588  893 
lemma nat_mult_min_right: "m * min n q = min (m * n) (m * q)" 
894 
for m n q :: nat 

63110  895 
by (simp add: min_def not_le) 
896 
(auto dest: mult_left_le_imp_le mult_left_less_imp_less le_less_trans) 

897 

63588  898 
lemma nat_add_max_left: "max m n + q = max (m + q) (n + q)" 
899 
for m n q :: nat 

44817  900 
by (simp add: max_def) 
901 

63588  902 
lemma nat_add_max_right: "m + max n q = max (m + n) (m + q)" 
903 
for m n q :: nat 

44817  904 
by (simp add: max_def) 
905 

63588  906 
lemma nat_mult_max_left: "max m n * q = max (m * q) (n * q)" 
907 
for m n q :: nat 

63110  908 
by (simp add: max_def not_le) 
909 
(auto dest: mult_right_le_imp_le mult_right_less_imp_less le_less_trans) 

910 

63588  911 
lemma nat_mult_max_right: "m * max n q = max (m * n) (m * q)" 
912 
for m n q :: nat 

63110  913 
by (simp add: max_def not_le) 
914 
(auto dest: mult_left_le_imp_le mult_left_less_imp_less le_less_trans) 

14267
b963e9cee2a0
More refinements to Ring_and_Field and numerics. Conversion of Divides_lemmas
paulson
parents:
14266
diff
changeset

915 

b963e9cee2a0
More refinements to Ring_and_Field and numerics. Conversion of Divides_lemmas
paulson
parents:
14266
diff
changeset

916 

60758  917 
subsubsection \<open>Additional theorems about @{term "op \<le>"}\<close> 
918 

919 
text \<open>Complete induction, aka courseofvalues induction\<close> 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

920 

63110  921 
instance nat :: wellorder 
922 
proof 

27823  923 
fix P and n :: nat 
63110  924 
assume step: "(\<And>m. m < n \<Longrightarrow> P m) \<Longrightarrow> P n" for n :: nat 
27823  925 
have "\<And>q. q \<le> n \<Longrightarrow> P q" 
926 
proof (induct n) 

927 
case (0 n) 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

928 
have "P 0" by (rule step) auto 
63588  929 
with 0 show ?case by auto 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

930 
next 
27823  931 
case (Suc m n) 
63588  932 
then have "n \<le> m \<or> n = Suc m" 
933 
by (simp add: le_Suc_eq) 

63110  934 
then show ?case 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

935 
proof 
63110  936 
assume "n \<le> m" 
937 
then show "P n" by (rule Suc(1)) 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

938 
next 
27823  939 
assume n: "n = Suc m" 
63110  940 
show "P n" by (rule step) (rule Suc(1), simp add: n le_simps) 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

941 
qed 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

942 
qed 
27823  943 
then show "P n" by auto 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

944 
qed 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

945 

57015  946 

63588  947 
lemma Least_eq_0[simp]: "P 0 \<Longrightarrow> Least P = 0" 
948 
for P :: "nat \<Rightarrow> bool" 

63110  949 
by (rule Least_equality[OF _ le0]) 
950 

951 
lemma Least_Suc: "P n \<Longrightarrow> \<not> P 0 \<Longrightarrow> (LEAST n. P n) = Suc (LEAST m. P (Suc m))" 

63588  952 
apply (cases n) 
953 
apply auto 

27823  954 
apply (frule LeastI) 
63588  955 
apply (drule_tac P = "\<lambda>x. P (Suc x)" in LeastI) 
27823  956 
apply (subgoal_tac " (LEAST x. P x) \<le> Suc (LEAST x. P (Suc x))") 
63588  957 
apply (erule_tac [2] Least_le) 
958 
apply (cases "LEAST x. P x") 

959 
apply auto 

960 
apply (drule_tac P = "\<lambda>x. P (Suc x)" in Least_le) 

27823  961 
apply (blast intro: order_antisym) 
962 
done 

963 

63110  964 
lemma Least_Suc2: "P n \<Longrightarrow> Q m \<Longrightarrow> \<not> P 0 \<Longrightarrow> \<forall>k. P (Suc k) = Q k \<Longrightarrow> Least P = Suc (Least Q)" 
63588  965 
by (erule (1) Least_Suc [THEN ssubst]) simp 
966 

967 
lemma ex_least_nat_le: "\<not> P 0 \<Longrightarrow> P n \<Longrightarrow> \<exists>k\<le>n. (\<forall>i<k. \<not> P i) \<and> P k" 

968 
for P :: "nat \<Rightarrow> bool" 

27823  969 
apply (cases n) 
970 
apply blast 

63110  971 
apply (rule_tac x="LEAST k. P k" in exI) 
27823  972 
apply (blast intro: Least_le dest: not_less_Least intro: LeastI_ex) 
973 
done 

974 

63588  975 
lemma ex_least_nat_less: "\<not> P 0 \<Longrightarrow> P n \<Longrightarrow> \<exists>k<n. (\<forall>i\<le>k. \<not> P i) \<and> P (k + 1)" 
976 
for P :: "nat \<Rightarrow> bool" 

27823  977 
apply (cases n) 
978 
apply blast 

979 
apply (frule (1) ex_least_nat_le) 

980 
apply (erule exE) 

981 
apply (case_tac k) 

982 
apply simp 

983 
apply (rename_tac k1) 

984 
apply (rule_tac x=k1 in exI) 

985 
apply (auto simp add: less_eq_Suc_le) 

986 
done 

987 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

988 
lemma nat_less_induct: 
63110  989 
fixes P :: "nat \<Rightarrow> bool" 
990 
assumes "\<And>n. \<forall>m. m < n \<longrightarrow> P m \<Longrightarrow> P n" 

991 
shows "P n" 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

992 
using assms less_induct by blast 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

993 

4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

994 
lemma measure_induct_rule [case_names less]: 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

995 
fixes f :: "'a \<Rightarrow> nat" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

996 
assumes step: "\<And>x. (\<And>y. f y < f x \<Longrightarrow> P y) \<Longrightarrow> P x" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

997 
shows "P a" 
63110  998 
by (induct m \<equiv> "f a" arbitrary: a rule: less_induct) (auto intro: step) 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

999 

60758  1000 
text \<open>old style induction rules:\<close> 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1001 
lemma measure_induct: 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1002 
fixes f :: "'a \<Rightarrow> nat" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1003 
shows "(\<And>x. \<forall>y. f y < f x \<longrightarrow> P y \<Longrightarrow> P x) \<Longrightarrow> P a" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1004 
by (rule measure_induct_rule [of f P a]) iprover 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1005 

4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1006 
lemma full_nat_induct: 
63110  1007 
assumes step: "\<And>n. (\<forall>m. Suc m \<le> n \<longrightarrow> P m) \<Longrightarrow> P n" 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1008 
shows "P n" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1009 
by (rule less_induct) (auto intro: step simp:le_simps) 
14267
b963e9cee2a0
More refinements to Ring_and_Field and numerics. Conversion of Divides_lemmas
paulson
parents:
14266
diff
changeset

1010 

63110  1011 
text\<open>An induction rule for establishing binary relations\<close> 
62683  1012 
lemma less_Suc_induct [consumes 1]: 
63110  1013 
assumes less: "i < j" 
1014 
and step: "\<And>i. P i (Suc i)" 

1015 
and trans: "\<And>i j k. i < j \<Longrightarrow> j < k \<Longrightarrow> P i j \<Longrightarrow> P j k \<Longrightarrow> P i k" 

19870  1016 
shows "P i j" 
1017 
proof  

63110  1018 
from less obtain k where j: "j = Suc (i + k)" 
1019 
by (auto dest: less_imp_Suc_add) 

22718  1020 
have "P i (Suc (i + k))" 
19870  1021 
proof (induct k) 
22718  1022 
case 0 
1023 
show ?case by (simp add: step) 

19870  1024 
next 
1025 
case (Suc k) 

31714  1026 
have "0 + i < Suc k + i" by (rule add_less_mono1) simp 
63110  1027 
then have "i < Suc (i + k)" by (simp add: add.commute) 
31714  1028 
from trans[OF this lessI Suc step] 
1029 
show ?case by simp 

19870  1030 
qed 
63110  1031 
then show "P i j" by (simp add: j) 
19870  1032 
qed 
1033 

63111  1034 
text \<open> 
1035 
The method of infinite descent, frequently used in number theory. 

1036 
Provided by Roelof Oosterhuis. 

1037 
\<open>P n\<close> is true for all natural numbers if 

1038 
\<^item> case ``0'': given \<open>n = 0\<close> prove \<open>P n\<close> 

1039 
\<^item> case ``smaller'': given \<open>n > 0\<close> and \<open>\<not> P n\<close> prove there exists 

1040 
a smaller natural number \<open>m\<close> such that \<open>\<not> P m\<close>. 

1041 
\<close> 

1042 

63110  1043 
lemma infinite_descent: "(\<And>n. \<not> P n \<Longrightarrow> \<exists>m<n. \<not> P m) \<Longrightarrow> P n" for P :: "nat \<Rightarrow> bool" 
63111  1044 
\<comment> \<open>compact version without explicit base case\<close> 
63110  1045 
by (induct n rule: less_induct) auto 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1046 

63111  1047 
lemma infinite_descent0 [case_names 0 smaller]: 
63110  1048 
fixes P :: "nat \<Rightarrow> bool" 
63111  1049 
assumes "P 0" 
1050 
and "\<And>n. n > 0 \<Longrightarrow> \<not> P n \<Longrightarrow> \<exists>m. m < n \<and> \<not> P m" 

63110  1051 
shows "P n" 
1052 
apply (rule infinite_descent) 

1053 
using assms 

1054 
apply (case_tac "n > 0") 

63588  1055 
apply auto 
63110  1056 
done 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1057 

60758  1058 
text \<open> 
63111  1059 
Infinite descent using a mapping to \<open>nat\<close>: 
1060 
\<open>P x\<close> is true for all \<open>x \<in> D\<close> if there exists a \<open>V \<in> D \<Rightarrow> nat\<close> and 

1061 
\<^item> case ``0'': given \<open>V x = 0\<close> prove \<open>P x\<close> 

1062 
\<^item> ``smaller'': given \<open>V x > 0\<close> and \<open>\<not> P x\<close> prove 

1063 
there exists a \<open>y \<in> D\<close> such that \<open>V y < V x\<close> and \<open>\<not> P y\<close>. 

1064 
\<close> 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1065 
corollary infinite_descent0_measure [case_names 0 smaller]: 
63110  1066 
fixes V :: "'a \<Rightarrow> nat" 
1067 
assumes 1: "\<And>x. V x = 0 \<Longrightarrow> P x" 

1068 
and 2: "\<And>x. V x > 0 \<Longrightarrow> \<not> P x \<Longrightarrow> \<exists>y. V y < V x \<and> \<not> P y" 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1069 
shows "P x" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1070 
proof  
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1071 
obtain n where "n = V x" by auto 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1072 
moreover have "\<And>x. V x = n \<Longrightarrow> P x" 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1073 
proof (induct n rule: infinite_descent0) 
63110  1074 
case 0 
1075 
with 1 show "P x" by auto 

1076 
next 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1077 
case (smaller n) 
63110  1078 
then obtain x where *: "V x = n " and "V x > 0 \<and> \<not> P x" by auto 
1079 
with 2 obtain y where "V y < V x \<and> \<not> P y" by auto 

63111  1080 
with * obtain m where "m = V y \<and> m < n \<and> \<not> P y" by auto 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1081 
then show ?case by auto 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1082 
qed 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1083 
ultimately show "P x" by auto 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1084 
qed 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1085 

63588  1086 
text \<open>Again, without explicit base case:\<close> 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1087 
lemma infinite_descent_measure: 
63110  1088 
fixes V :: "'a \<Rightarrow> nat" 
1089 
assumes "\<And>x. \<not> P x \<Longrightarrow> \<exists>y. V y < V x \<and> \<not> P y" 

1090 
shows "P x" 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1091 
proof  
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1092 
from assms obtain n where "n = V x" by auto 
63110  1093 
moreover have "\<And>x. V x = n \<Longrightarrow> P x" 
26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1094 
proof (induct n rule: infinite_descent, auto) 
63111  1095 
show "\<exists>m < V x. \<exists>y. V y = m \<and> \<not> P y" if "\<not> P x" for x 
1096 
using assms and that by auto 

26748
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1097 
qed 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1098 
ultimately show "P x" by auto 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1099 
qed 
4d51ddd6aa5c
Merged theories about wellfoundedness into one: Wellfounded.thy
krauss
parents:
26335
diff
changeset

1100 

63111  1101 
text \<open>A (clumsy) way of lifting \<open><\<close> monotonicity to \<open>\<le>\<close> monotonicity\<close> 
14267
b963e9cee2a0
More refinements to Ring_and_Field and numerics. Conversion of Divides_lemmas
paulson
parents:
14266
diff
changeset

1102 
lemma less_mono_imp_le_mono: 
63110  1103 
fixes f :: "nat \<Rightarrow> nat" 
1104 
and i j :: nat 

1105 
assumes "\<And>i j::nat. i < j \<Longrightarrow> f i < f j" 

1106 
and "i \<le> j" 

1107 
shows "f i \<le> f j" 

1108 
using assms by (auto simp add: order_le_less) 

24438  1109 

14267
b963e9cee2a0
More refinements to Ring_and_Field and numerics. Conversion of Divides_lemmas
paulson
parents:
14266
diff
changeset

1110 

60758  1111 
text \<open>nonstrict, in 1st argument\<close> 
63588  1112 
lemma add_le_mono1: "i \<le> j \<Longrightarrow> i + k \<le> j + k" 
1113 
for i j k :: nat 

63110  1114 
by (rule add_right_mono) 
14267
b963e9cee2a0
More refinements to Ring_and_Field and numerics. Conversion of Divides_lemmas
paulson
parents:
14266
diff
changeset

1115 

60758  1116 
text \<open>nonstrict, in both arguments\<close> 
63588  1117 
lemma add_le_mono: "i \<le> j \<Longrightarrow> k \<le> l \<Longrightarrow> i + k \<le> j + l" 
1118 
for i j k l :: nat 

63110  1119 
by (rule add_mono) 
1120 

63588  1121 
lemma le_add2: "n \<le> m + n" 
1122 
for m n :: nat 

62608  1123 
by simp 
13449  1124 

63588  1125 
lemma le_add1: "n \<le> n + m" 
1126 
for m n :: nat 

62608  1127 
by simp 
13449  1128 

1129 
lemma less_add_Suc1: "i < Suc (i + m)" 

63110  1130 
by (rule le_less_trans, rule le_add1, rule lessI) 
13449  1131 

1132 
lemma less_add_Suc2: "i < Suc (m + i)" 

63110  1133 
by (rule le_less_trans, rule le_add2, rule lessI) 
1134 

1135 
lemma less_iff_Suc_add: "m < n \<longleftrightarrow> (\<exists>k. n = Suc (m + k))" 

1136 
by (iprover intro!: less_add_Suc1 less_imp_Suc_add) 

1137 

63588  1138 
lemma trans_le_add1: "i \<le> j \<Longrightarrow> i \<le> j + m" 
1139 
for i j m :: nat 

63110  1140 
by (rule le_trans, assumption, rule le_add1) 
1141 

63588  1142 
lemma trans_le_add2: "i \<le> j \<Longrightarrow> i \<le> m + j" 
1143 
for i j m :: nat 

63110  1144 
by (rule le_trans, assumption, rule le_add2) 
1145 

63588  1146 
lemma trans_less_add1: "i < j \<Longrightarrow> i < j + m" 
1147 
for i j m :: nat 

63110  1148 
by (rule less_le_trans, assumption, rule le_add1) 
1149 

63588  1150 
lemma trans_less_add2: "i < j \<Longrightarrow> i < m + j" 
1151 
for i j m :: nat 

63110  1152 
by (rule less_le_trans, assumption, rule le_add2) 
1153 

63588  1154 
lemma add_lessD1: "i + j < k \<Longrightarrow> i < k" 
1155 
for i j k :: nat 

63110  1156 
by (rule le_less_trans [of _ "i+j"]) (simp_all add: le_add1) 
1157 

63588  1158 
lemma not_add_less1 [iff]: "\<not> i + j < i" 
1159 
for i j :: nat 

63110  1160 
apply (rule notI) 
1161 
apply (drule add_lessD1) 

1162 
apply (erule less_irrefl [THEN notE]) 

1163 
done 

1164 

63588  1165 
lemma not_add_less2 [iff]: "\<not> j + i < i" 
1166 
for i j :: nat 

63110  1167 
by (simp add: add.commute) 
1168 

63588  1169 
lemma add_leD1: "m + k \<le> n \<Longrightarrow> m \<le> n" 
1170 
for k m n :: nat 

1171 
by (rule order_trans [of _ "m + k"]) (simp_all add: le_add1) 

1172 

1173 
lemma add_leD2: "m + k \<le> n \<Longrightarrow> k \<le> n" 

1174 
for k m n :: nat 

63110  1175 
apply (simp add: add.commute) 
1176 
apply (erule add_leD1) 

1177 
done 

1178 

63588  1179 
lemma add_leE: "m + k \<le> n \<Longrightarrow> (m \<le> n \<Longrightarrow> k \<le> n \<Longrightarrow> R) \<Longrightarrow> R" 
1180 
for k m n :: nat 

63110  1181 
by (blast dest: add_leD1 add_leD2) 
1182 

1183 
text \<open>needs \<open>\<And>k\<close> for \<open>ac_simps\<close> to work\<close> 

63588  1184 
lemma less_add_eq_less: "\<And>k. k < l \<Longrightarrow> m + l = k + n \<Longrightarrow> m < n" 
1185 
for l m n :: nat 

63110  1186 
by (force simp del: add_Suc_right simp add: less_iff_Suc_add add_Suc_right [symmetric] ac_simps) 
13449  1187 

1188 

60758  1189 
subsubsection \<open>More results about difference\<close> 
13449  1190 

63110  1191 
lemma Suc_diff_le: "n \<le> m \<Longrightarrow> Suc m  n = Suc (m  n)" 
1192 
by (induct m n rule: diff_induct) simp_all 

13449  1193 

1194 
lemma diff_less_Suc: "m  n < Suc m" 

63588  1195 
apply (induct m n rule: diff_induct) 
1196 
apply (erule_tac [3] less_SucE) 

1197 
apply (simp_all add: less_Suc_eq) 

1198 
done 

1199 

1200 
lemma diff_le_self [simp]: "m  n \<le> m" 

1201 
for m n :: nat 

63110  1202 
by (induct m n rule: diff_induct) (simp_all add: le_SucI) 
1203 

63588  1204 
lemma less_imp_diff_less: "j < k \<Longrightarrow> j  n < k" 
1205 
for j k n :: nat 

63110  1206 
by (rule le_less_trans, rule diff_le_self) 
1207 

1208 
lemma diff_Suc_less [simp]: "0 < n \<Longrightarrow> n  Suc i < n" 

1209 
by (cases n) (auto simp add: le_simps) 

1210 

63588  1211 
lemma diff_add_assoc: "k \<le> j \<Longrightarrow> (i + j)  k = i + (j  k)" 
1212 
for i j k :: nat 

63110  1213 
by (induct j k rule: diff_induct) simp_all 
1214 

63588  1215 
lemma add_diff_assoc [simp]: "k \<le> j \<Longrightarrow> i + (j  k) = i + j  k" 
1216 
for i j k :: nat 

62481
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

1217 
by (fact diff_add_assoc [symmetric]) 
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

1218 

63588  1219 
lemma diff_add_assoc2: "k \<le> j \<Longrightarrow> (j + i)  k = (j  k) + i" 
1220 
for i j k :: nat 

62481
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

1221 
by (simp add: ac_simps) 
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

1222 

63588  1223 
lemma add_diff_assoc2 [simp]: "k \<le> j \<Longrightarrow> j  k + i = j + i  k" 
1224 
for i j k :: nat 

62481
b5d8e57826df
tuned bootstrap order to provide type classes in a more sensible order
haftmann
parents:
62378
diff
changeset

1225 
by (fact diff_add_assoc2 [symmetric]) 
13449  1226 

63588  1227 
lemma le_imp_diff_is_add: "i \<le> j \<Longrightarrow> (j  i = k) = (j = k + i)" 
1228 
for i j k :: nat 

63110  1229 
by auto 
1230 

63588  1231 
lemma diff_is_0_eq [simp]: "m  n = 0 \<longleftrightarrow> m \<le> n" 
1232 
for m n :: nat 

63110  1233 
by (induct m n rule: diff_induct) simp_all 
1234 

63588  1235 
lemma diff_is_0_eq' [simp]: "m \<le> n \<Longrightarrow> m  n = 0" 
1236 
for m n :: nat 

63110  1237 
by (rule iffD2, rule diff_is_0_eq) 
1238 

63588  1239 
lemma zero_less_diff [simp]: "0 < n  m \<longleftrightarrow> m < n" 
1240 
for m n :: nat 

63110  1241 
by (induct m n rule: diff_induct) simp_all 
13449  1242 

22718  1243 
lemma less_imp_add_positive: 
1244 
assumes "i < j" 

63110  1245 
shows "\<exists>k::nat. 0 < k \<and> i + k = j" 
22718  1246 
proof 
63110  1247 
from assms show "0 < j  i \<and> i + (j  i) = j" 
23476  1248 
by (simp add: order_less_imp_le) 
22718  1249 
qed 
9436
62bb04ab4b01
rearranged setup of arithmetic procedures, avoiding global reference values;
wenzelm
parents:
7702
diff
changeset

1250 

60758  1251 
text \<open>a nice rewrite for bounded subtraction\<close> 
63588  1252 
lemma nat_minus_add_max: "n  m + m = max n m" 
1253 
for m n :: nat 

1254 
by (simp add: max_def not_le order_less_imp_le) 

13449  1255 

63110  1256 
lemma nat_diff_split: "P (a  b) \<longleftrightarrow> (a < b \<longrightarrow> P 0) \<and> (\<forall>d. a = b + d \<longrightarrow> P d)" 
1257 
for a b :: nat 

63588  1258 
\<comment> \<open>elimination of \<open>\<close> on \<open>nat\<close>\<close> 
1259 
by (cases "a < b") (auto simp add: not_less le_less dest!: add_eq_self_zero [OF sym]) 

13449  1260 

63110  1261 
lemma nat_diff_split_asm: "P (a  b) \<longleftrightarrow> \<not> (a < b \<and> \<not> P 0 \<or> (\<exists>d. a = b + d \<and> \<not> P d))" 
1262 
for a b :: nat 

63588  1263 
\<comment> \<open>elimination of \<open>\<close> on \<open>nat\<close> in assumptions\<close> 
62365  1264 
by (auto split: nat_diff_split) 
13449  1265 

63110  1266 
lemma Suc_pred': "0 < n \<Longrightarrow> n = Suc(n  1)" 
47255
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1267 
by simp 
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1268 

63110  1269 
lemma add_eq_if: "m + n = (if m = 0 then n else Suc ((m  1) + n))" 
47255
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1270 
unfolding One_nat_def by (cases m) simp_all 
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1271 

63588  1272 
lemma mult_eq_if: "m * n = (if m = 0 then 0 else n + ((m  1) * n))" 
1273 
for m n :: nat 

1274 
by (cases m) simp_all 

47255
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1275 

63110  1276 
lemma Suc_diff_eq_diff_pred: "0 < n \<Longrightarrow> Suc m  n = m  (n  1)" 
63588  1277 
by (cases n) simp_all 
47255
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1278 

30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1279 
lemma diff_Suc_eq_diff_pred: "m  Suc n = (m  1)  n" 
63588  1280 
by (cases m) simp_all 
1281 

1282 
lemma Let_Suc [simp]: "Let (Suc n) f \<equiv> f (Suc n)" 

47255
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1283 
by (fact Let_def) 
30a1692557b0
removed Nat_Numeral.thy, moving all theorems elsewhere
huffman
parents:
47208
diff
changeset

1284 

13449  1285 

60758  1286 
subsubsection \<open>Monotonicity of multiplication\<close> 
13449  1287 

63588  1288 
lemma mult_le_mono1: "i \<le> j \<Longrightarrow> i * k \<le> j * k" 
1289 
for i j k :: nat 

63110  1290 
by (simp add: mult_right_mono) 
1291 

63588  1292 
lemma mult_le_mono2: "i \<le> j \<Longrightarrow> k * i \<le> k * j" 
1293 
for i j k :: nat 

63110  1294 
by (simp add: mult_left_mono) 
13449  1295 

61799  1296 
text \<open>\<open>\<le>\<close> monotonicity, BOTH arguments\<close> 
63588  1297 
lemma mult_le_mono: "i \<le> j \<Longrightarrow> k \<le> l \<Longrightarrow> i * k \<le> j * l" 
1298 
for i j k l :: nat 

63110  1299 
by (simp add: mult_mono) 
1300 

63588  1301 
lemma mult_less_mono1: "i < j \<Longrightarrow> 0 < k \<Longrightarrow> i * k < j * k" 
1302 
for i j k :: nat 

63110  1303 
by (simp add: mult_strict_right_mono) 
13449  1304 

63588  1305 
text \<open>Differs from the standard \<open>zero_less_mult_iff\<close> in that there are no negative numbers.\<close> 
1306 
lemma nat_0_less_mult_iff [simp]: "0 < m * n \<longleftrightarrow> 0 < m \<and> 0 < n" 

1307 
for m n :: nat 

1308 
proof (induct m) 

1309 
case 0 

1310 
then show ?case by simp 

1311 
next 

1312 
case (Suc m) 
