src/HOL/Int.thy
author haftmann
Sat Aug 08 10:51:33 2015 +0200 (2015-08-08)
changeset 60868 dd18c33c001e
parent 60758 d8d85a8172b5
child 61070 b72a990adfe2
permissions -rw-r--r--
direct bootstrap of integer division from natural division
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(*  Title:      HOL/Int.thy
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Author:     Tobias Nipkow, Florian Haftmann, TU Muenchen
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*)
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section \<open>The Integers as Equivalence Classes over Pairs of Natural Numbers\<close>
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theory Int
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imports Equiv_Relations Power Quotient Fun_Def
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begin
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subsection \<open>Definition of integers as a quotient type\<close>
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definition intrel :: "(nat \<times> nat) \<Rightarrow> (nat \<times> nat) \<Rightarrow> bool" where
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  "intrel = (\<lambda>(x, y) (u, v). x + v = u + y)"
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lemma intrel_iff [simp]: "intrel (x, y) (u, v) \<longleftrightarrow> x + v = u + y"
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  by (simp add: intrel_def)
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quotient_type int = "nat \<times> nat" / "intrel"
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  morphisms Rep_Integ Abs_Integ
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proof (rule equivpI)
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  show "reflp intrel"
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    unfolding reflp_def by auto
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  show "symp intrel"
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    unfolding symp_def by auto
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  show "transp intrel"
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    unfolding transp_def by auto
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qed
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lemma eq_Abs_Integ [case_names Abs_Integ, cases type: int]:
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     "(!!x y. z = Abs_Integ (x, y) ==> P) ==> P"
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by (induct z) auto
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subsection \<open>Integers form a commutative ring\<close>
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instantiation int :: comm_ring_1
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begin
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lift_definition zero_int :: "int" is "(0, 0)" .
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lift_definition one_int :: "int" is "(1, 0)" .
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lift_definition plus_int :: "int \<Rightarrow> int \<Rightarrow> int"
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  is "\<lambda>(x, y) (u, v). (x + u, y + v)"
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  by clarsimp
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lift_definition uminus_int :: "int \<Rightarrow> int"
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  is "\<lambda>(x, y). (y, x)"
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  by clarsimp
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lift_definition minus_int :: "int \<Rightarrow> int \<Rightarrow> int"
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  is "\<lambda>(x, y) (u, v). (x + v, y + u)"
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  by clarsimp
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lift_definition times_int :: "int \<Rightarrow> int \<Rightarrow> int"
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  is "\<lambda>(x, y) (u, v). (x*u + y*v, x*v + y*u)"
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proof (clarsimp)
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  fix s t u v w x y z :: nat
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  assume "s + v = u + t" and "w + z = y + x"
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  hence "(s + v) * w + (u + t) * x + u * (w + z) + v * (y + x)
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       = (u + t) * w + (s + v) * x + u * (y + x) + v * (w + z)"
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    by simp
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  thus "(s * w + t * x) + (u * z + v * y) = (u * y + v * z) + (s * x + t * w)"
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    by (simp add: algebra_simps)
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qed
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instance
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  by default (transfer, clarsimp simp: algebra_simps)+
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end
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abbreviation int :: "nat \<Rightarrow> int" where
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  "int \<equiv> of_nat"
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lemma int_def: "int n = Abs_Integ (n, 0)"
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  by (induct n, simp add: zero_int.abs_eq,
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    simp add: one_int.abs_eq plus_int.abs_eq)
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lemma int_transfer [transfer_rule]:
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  "(rel_fun (op =) pcr_int) (\<lambda>n. (n, 0)) int"
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  unfolding rel_fun_def int.pcr_cr_eq cr_int_def int_def by simp
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lemma int_diff_cases:
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  obtains (diff) m n where "z = int m - int n"
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  by transfer clarsimp
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subsection \<open>Integers are totally ordered\<close>
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instantiation int :: linorder
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begin
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lift_definition less_eq_int :: "int \<Rightarrow> int \<Rightarrow> bool"
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  is "\<lambda>(x, y) (u, v). x + v \<le> u + y"
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  by auto
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lift_definition less_int :: "int \<Rightarrow> int \<Rightarrow> bool"
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  is "\<lambda>(x, y) (u, v). x + v < u + y"
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  by auto
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instance
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  by default (transfer, force)+
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end
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instantiation int :: distrib_lattice
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begin
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definition
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  "(inf \<Colon> int \<Rightarrow> int \<Rightarrow> int) = min"
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definition
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  "(sup \<Colon> int \<Rightarrow> int \<Rightarrow> int) = max"
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instance
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  by intro_classes
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    (auto simp add: inf_int_def sup_int_def max_min_distrib2)
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end
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subsection \<open>Ordering properties of arithmetic operations\<close>
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instance int :: ordered_cancel_ab_semigroup_add
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proof
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  fix i j k :: int
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  show "i \<le> j \<Longrightarrow> k + i \<le> k + j"
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    by transfer clarsimp
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qed
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text\<open>Strict Monotonicity of Multiplication\<close>
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text\<open>strict, in 1st argument; proof is by induction on k>0\<close>
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lemma zmult_zless_mono2_lemma:
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     "(i::int)<j ==> 0<k ==> int k * i < int k * j"
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apply (induct k)
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apply simp
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apply (simp add: distrib_right)
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apply (case_tac "k=0")
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apply (simp_all add: add_strict_mono)
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done
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lemma zero_le_imp_eq_int: "(0::int) \<le> k ==> \<exists>n. k = int n"
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apply transfer
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apply clarsimp
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apply (rule_tac x="a - b" in exI, simp)
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done
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lemma zero_less_imp_eq_int: "(0::int) < k ==> \<exists>n>0. k = int n"
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apply transfer
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apply clarsimp
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apply (rule_tac x="a - b" in exI, simp)
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done
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lemma zmult_zless_mono2: "[| i<j;  (0::int) < k |] ==> k*i < k*j"
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apply (drule zero_less_imp_eq_int)
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apply (auto simp add: zmult_zless_mono2_lemma)
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done
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text\<open>The integers form an ordered integral domain\<close>
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instantiation int :: linordered_idom
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begin
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definition
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  zabs_def: "\<bar>i\<Colon>int\<bar> = (if i < 0 then - i else i)"
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definition
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  zsgn_def: "sgn (i\<Colon>int) = (if i=0 then 0 else if 0<i then 1 else - 1)"
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instance proof
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  fix i j k :: int
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  show "i < j \<Longrightarrow> 0 < k \<Longrightarrow> k * i < k * j"
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    by (rule zmult_zless_mono2)
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  show "\<bar>i\<bar> = (if i < 0 then -i else i)"
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    by (simp only: zabs_def)
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  show "sgn (i\<Colon>int) = (if i=0 then 0 else if 0<i then 1 else - 1)"
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    by (simp only: zsgn_def)
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qed
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end
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lemma zless_imp_add1_zle: "w < z \<Longrightarrow> w + (1\<Colon>int) \<le> z"
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  by transfer clarsimp
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lemma zless_iff_Suc_zadd:
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  "(w \<Colon> int) < z \<longleftrightarrow> (\<exists>n. z = w + int (Suc n))"
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apply transfer
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apply auto
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apply (rename_tac a b c d)
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apply (rule_tac x="c+b - Suc(a+d)" in exI)
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apply arith
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done
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lemmas int_distrib =
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  distrib_right [of z1 z2 w]
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  distrib_left [of w z1 z2]
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  left_diff_distrib [of z1 z2 w]
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  right_diff_distrib [of w z1 z2]
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  for z1 z2 w :: int
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subsection \<open>Embedding of the Integers into any @{text ring_1}: @{text of_int}\<close>
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context ring_1
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begin
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lift_definition of_int :: "int \<Rightarrow> 'a" is "\<lambda>(i, j). of_nat i - of_nat j"
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  by (clarsimp simp add: diff_eq_eq eq_diff_eq diff_add_eq
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    of_nat_add [symmetric] simp del: of_nat_add)
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lemma of_int_0 [simp]: "of_int 0 = 0"
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  by transfer simp
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lemma of_int_1 [simp]: "of_int 1 = 1"
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  by transfer simp
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lemma of_int_add [simp]: "of_int (w+z) = of_int w + of_int z"
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  by transfer (clarsimp simp add: algebra_simps)
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lemma of_int_minus [simp]: "of_int (-z) = - (of_int z)"
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  by (transfer fixing: uminus) clarsimp
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lemma of_int_diff [simp]: "of_int (w - z) = of_int w - of_int z"
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  using of_int_add [of w "- z"] by simp
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lemma of_int_mult [simp]: "of_int (w*z) = of_int w * of_int z"
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  by (transfer fixing: times) (clarsimp simp add: algebra_simps of_nat_mult)
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text\<open>Collapse nested embeddings\<close>
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lemma of_int_of_nat_eq [simp]: "of_int (int n) = of_nat n"
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by (induct n) auto
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lemma of_int_numeral [simp, code_post]: "of_int (numeral k) = numeral k"
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  by (simp add: of_nat_numeral [symmetric] of_int_of_nat_eq [symmetric])
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lemma of_int_neg_numeral [code_post]: "of_int (- numeral k) = - numeral k"
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  by simp
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lemma of_int_power:
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  "of_int (z ^ n) = of_int z ^ n"
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  by (induct n) simp_all
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end
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context ring_char_0
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begin
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lemma of_int_eq_iff [simp]:
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   "of_int w = of_int z \<longleftrightarrow> w = z"
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  by transfer (clarsimp simp add: algebra_simps
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    of_nat_add [symmetric] simp del: of_nat_add)
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text\<open>Special cases where either operand is zero\<close>
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lemma of_int_eq_0_iff [simp]:
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  "of_int z = 0 \<longleftrightarrow> z = 0"
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  using of_int_eq_iff [of z 0] by simp
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lemma of_int_0_eq_iff [simp]:
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  "0 = of_int z \<longleftrightarrow> z = 0"
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  using of_int_eq_iff [of 0 z] by simp
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end
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context linordered_idom
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begin
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text\<open>Every @{text linordered_idom} has characteristic zero.\<close>
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subclass ring_char_0 ..
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lemma of_int_le_iff [simp]:
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  "of_int w \<le> of_int z \<longleftrightarrow> w \<le> z"
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  by (transfer fixing: less_eq) (clarsimp simp add: algebra_simps
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    of_nat_add [symmetric] simp del: of_nat_add)
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lemma of_int_less_iff [simp]:
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  "of_int w < of_int z \<longleftrightarrow> w < z"
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  by (simp add: less_le order_less_le)
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lemma of_int_0_le_iff [simp]:
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  "0 \<le> of_int z \<longleftrightarrow> 0 \<le> z"
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  using of_int_le_iff [of 0 z] by simp
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lemma of_int_le_0_iff [simp]:
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  "of_int z \<le> 0 \<longleftrightarrow> z \<le> 0"
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  using of_int_le_iff [of z 0] by simp
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lemma of_int_0_less_iff [simp]:
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  "0 < of_int z \<longleftrightarrow> 0 < z"
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  using of_int_less_iff [of 0 z] by simp
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lemma of_int_less_0_iff [simp]:
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  "of_int z < 0 \<longleftrightarrow> z < 0"
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  using of_int_less_iff [of z 0] by simp
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end
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lemma of_nat_less_of_int_iff:
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  "(of_nat n::'a::linordered_idom) < of_int x \<longleftrightarrow> int n < x"
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  by (metis of_int_of_nat_eq of_int_less_iff)
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lemma of_int_eq_id [simp]: "of_int = id"
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proof
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  fix z show "of_int z = id z"
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    by (cases z rule: int_diff_cases, simp)
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qed
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instance int :: no_top
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  apply default
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  apply (rule_tac x="x + 1" in exI)
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  apply simp
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  done
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instance int :: no_bot
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  apply default
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  apply (rule_tac x="x - 1" in exI)
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  apply simp
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  done
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subsection \<open>Magnitude of an Integer, as a Natural Number: @{text nat}\<close>
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lift_definition nat :: "int \<Rightarrow> nat" is "\<lambda>(x, y). x - y"
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  by auto
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lemma nat_int [simp]: "nat (int n) = n"
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  by transfer simp
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lemma int_nat_eq [simp]: "int (nat z) = (if 0 \<le> z then z else 0)"
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  by transfer clarsimp
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corollary nat_0_le: "0 \<le> z ==> int (nat z) = z"
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by simp
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lemma nat_le_0 [simp]: "z \<le> 0 ==> nat z = 0"
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  by transfer clarsimp
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lemma nat_le_eq_zle: "0 < w | 0 \<le> z ==> (nat w \<le> nat z) = (w\<le>z)"
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  by transfer (clarsimp, arith)
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text\<open>An alternative condition is @{term "0 \<le> w"}\<close>
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corollary nat_mono_iff: "0 < z ==> (nat w < nat z) = (w < z)"
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by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
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   342
haftmann@25919
   343
corollary nat_less_eq_zless: "0 \<le> w ==> (nat w < nat z) = (w<z)"
lp15@60162
   344
by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
haftmann@25919
   345
haftmann@25919
   346
lemma zless_nat_conj [simp]: "(nat w < nat z) = (0 < z & w < z)"
huffman@48045
   347
  by transfer (clarsimp, arith)
haftmann@25919
   348
haftmann@25919
   349
lemma nonneg_eq_int:
haftmann@25919
   350
  fixes z :: int
huffman@44709
   351
  assumes "0 \<le> z" and "\<And>m. z = int m \<Longrightarrow> P"
haftmann@25919
   352
  shows P
haftmann@25919
   353
  using assms by (blast dest: nat_0_le sym)
haftmann@25919
   354
haftmann@54223
   355
lemma nat_eq_iff:
haftmann@54223
   356
  "nat w = m \<longleftrightarrow> (if 0 \<le> w then w = int m else m = 0)"
huffman@48045
   357
  by transfer (clarsimp simp add: le_imp_diff_is_add)
lp15@60162
   358
haftmann@54223
   359
corollary nat_eq_iff2:
haftmann@54223
   360
  "m = nat w \<longleftrightarrow> (if 0 \<le> w then w = int m else m = 0)"
haftmann@54223
   361
  using nat_eq_iff [of w m] by auto
haftmann@54223
   362
haftmann@54223
   363
lemma nat_0 [simp]:
haftmann@54223
   364
  "nat 0 = 0"
haftmann@54223
   365
  by (simp add: nat_eq_iff)
haftmann@25919
   366
haftmann@54223
   367
lemma nat_1 [simp]:
haftmann@54223
   368
  "nat 1 = Suc 0"
haftmann@54223
   369
  by (simp add: nat_eq_iff)
haftmann@54223
   370
haftmann@54223
   371
lemma nat_numeral [simp]:
haftmann@54223
   372
  "nat (numeral k) = numeral k"
haftmann@54223
   373
  by (simp add: nat_eq_iff)
haftmann@25919
   374
haftmann@54223
   375
lemma nat_neg_numeral [simp]:
haftmann@54489
   376
  "nat (- numeral k) = 0"
haftmann@54223
   377
  by simp
haftmann@54223
   378
haftmann@54223
   379
lemma nat_2: "nat 2 = Suc (Suc 0)"
haftmann@54223
   380
  by simp
lp15@60162
   381
haftmann@25919
   382
lemma nat_less_iff: "0 \<le> w ==> (nat w < m) = (w < of_nat m)"
huffman@48045
   383
  by transfer (clarsimp, arith)
haftmann@25919
   384
huffman@44709
   385
lemma nat_le_iff: "nat x \<le> n \<longleftrightarrow> x \<le> int n"
huffman@48045
   386
  by transfer (clarsimp simp add: le_diff_conv)
huffman@44707
   387
huffman@44707
   388
lemma nat_mono: "x \<le> y \<Longrightarrow> nat x \<le> nat y"
huffman@48045
   389
  by transfer auto
huffman@44707
   390
nipkow@29700
   391
lemma nat_0_iff[simp]: "nat(i::int) = 0 \<longleftrightarrow> i\<le>0"
huffman@48045
   392
  by transfer clarsimp
nipkow@29700
   393
haftmann@25919
   394
lemma int_eq_iff: "(of_nat m = z) = (m = nat z & 0 \<le> z)"
haftmann@25919
   395
by (auto simp add: nat_eq_iff2)
haftmann@25919
   396
haftmann@25919
   397
lemma zero_less_nat_eq [simp]: "(0 < nat z) = (0 < z)"
haftmann@25919
   398
by (insert zless_nat_conj [of 0], auto)
haftmann@25919
   399
haftmann@25919
   400
lemma nat_add_distrib:
haftmann@54223
   401
  "0 \<le> z \<Longrightarrow> 0 \<le> z' \<Longrightarrow> nat (z + z') = nat z + nat z'"
huffman@48045
   402
  by transfer clarsimp
haftmann@25919
   403
haftmann@54223
   404
lemma nat_diff_distrib':
haftmann@54223
   405
  "0 \<le> x \<Longrightarrow> 0 \<le> y \<Longrightarrow> nat (x - y) = nat x - nat y"
haftmann@54223
   406
  by transfer clarsimp
lp15@60162
   407
haftmann@25919
   408
lemma nat_diff_distrib:
haftmann@54223
   409
  "0 \<le> z' \<Longrightarrow> z' \<le> z \<Longrightarrow> nat (z - z') = nat z - nat z'"
haftmann@54223
   410
  by (rule nat_diff_distrib') auto
haftmann@25919
   411
huffman@44709
   412
lemma nat_zminus_int [simp]: "nat (- int n) = 0"
huffman@48045
   413
  by transfer simp
haftmann@25919
   414
haftmann@53065
   415
lemma le_nat_iff:
haftmann@53065
   416
  "k \<ge> 0 \<Longrightarrow> n \<le> nat k \<longleftrightarrow> int n \<le> k"
haftmann@53065
   417
  by transfer auto
lp15@60162
   418
huffman@44709
   419
lemma zless_nat_eq_int_zless: "(m < nat z) = (int m < z)"
huffman@48045
   420
  by transfer (clarsimp simp add: less_diff_conv)
haftmann@25919
   421
haftmann@25919
   422
context ring_1
haftmann@25919
   423
begin
haftmann@25919
   424
haftmann@25919
   425
lemma of_nat_nat: "0 \<le> z \<Longrightarrow> of_nat (nat z) = of_int z"
huffman@48066
   426
  by transfer (clarsimp simp add: of_nat_diff)
haftmann@25919
   427
haftmann@25919
   428
end
haftmann@25919
   429
lp15@60162
   430
lemma diff_nat_numeral [simp]:
haftmann@54249
   431
  "(numeral v :: nat) - numeral v' = nat (numeral v - numeral v')"
haftmann@54249
   432
  by (simp only: nat_diff_distrib' zero_le_numeral nat_numeral)
haftmann@54249
   433
haftmann@54249
   434
wenzelm@60758
   435
text \<open>For termination proofs:\<close>
krauss@29779
   436
lemma measure_function_int[measure_function]: "is_measure (nat o abs)" ..
krauss@29779
   437
haftmann@25919
   438
wenzelm@60758
   439
subsection\<open>Lemmas about the Function @{term of_nat} and Orderings\<close>
haftmann@25919
   440
huffman@44709
   441
lemma negative_zless_0: "- (int (Suc n)) < (0 \<Colon> int)"
haftmann@25919
   442
by (simp add: order_less_le del: of_nat_Suc)
haftmann@25919
   443
huffman@44709
   444
lemma negative_zless [iff]: "- (int (Suc n)) < int m"
haftmann@25919
   445
by (rule negative_zless_0 [THEN order_less_le_trans], simp)
haftmann@25919
   446
huffman@44709
   447
lemma negative_zle_0: "- int n \<le> 0"
haftmann@25919
   448
by (simp add: minus_le_iff)
haftmann@25919
   449
huffman@44709
   450
lemma negative_zle [iff]: "- int n \<le> int m"
haftmann@25919
   451
by (rule order_trans [OF negative_zle_0 of_nat_0_le_iff])
haftmann@25919
   452
huffman@44709
   453
lemma not_zle_0_negative [simp]: "~ (0 \<le> - (int (Suc n)))"
haftmann@25919
   454
by (subst le_minus_iff, simp del: of_nat_Suc)
haftmann@25919
   455
huffman@44709
   456
lemma int_zle_neg: "(int n \<le> - int m) = (n = 0 & m = 0)"
huffman@48045
   457
  by transfer simp
haftmann@25919
   458
huffman@44709
   459
lemma not_int_zless_negative [simp]: "~ (int n < - int m)"
haftmann@25919
   460
by (simp add: linorder_not_less)
haftmann@25919
   461
huffman@44709
   462
lemma negative_eq_positive [simp]: "(- int n = of_nat m) = (n = 0 & m = 0)"
haftmann@25919
   463
by (force simp add: order_eq_iff [of "- of_nat n"] int_zle_neg)
haftmann@25919
   464
huffman@44709
   465
lemma zle_iff_zadd: "w \<le> z \<longleftrightarrow> (\<exists>n. z = w + int n)"
haftmann@25919
   466
proof -
haftmann@25919
   467
  have "(w \<le> z) = (0 \<le> z - w)"
haftmann@25919
   468
    by (simp only: le_diff_eq add_0_left)
haftmann@25919
   469
  also have "\<dots> = (\<exists>n. z - w = of_nat n)"
haftmann@25919
   470
    by (auto elim: zero_le_imp_eq_int)
haftmann@25919
   471
  also have "\<dots> = (\<exists>n. z = w + of_nat n)"
nipkow@29667
   472
    by (simp only: algebra_simps)
haftmann@25919
   473
  finally show ?thesis .
haftmann@25919
   474
qed
haftmann@25919
   475
huffman@44709
   476
lemma zadd_int_left: "int m + (int n + z) = int (m + n) + z"
haftmann@25919
   477
by simp
haftmann@25919
   478
huffman@44709
   479
lemma int_Suc0_eq_1: "int (Suc 0) = 1"
haftmann@25919
   480
by simp
haftmann@25919
   481
wenzelm@60758
   482
text\<open>This version is proved for all ordered rings, not just integers!
haftmann@25919
   483
      It is proved here because attribute @{text arith_split} is not available
haftmann@35050
   484
      in theory @{text Rings}.
wenzelm@60758
   485
      But is it really better than just rewriting with @{text abs_if}?\<close>
blanchet@54147
   486
lemma abs_split [arith_split, no_atp]:
haftmann@35028
   487
     "P(abs(a::'a::linordered_idom)) = ((0 \<le> a --> P a) & (a < 0 --> P(-a)))"
haftmann@25919
   488
by (force dest: order_less_le_trans simp add: abs_if linorder_not_less)
haftmann@25919
   489
huffman@44709
   490
lemma negD: "x < 0 \<Longrightarrow> \<exists>n. x = - (int (Suc n))"
huffman@48045
   491
apply transfer
huffman@48045
   492
apply clarsimp
huffman@48045
   493
apply (rule_tac x="b - Suc a" in exI, arith)
haftmann@25919
   494
done
haftmann@25919
   495
wenzelm@60758
   496
subsection \<open>Cases and induction\<close>
haftmann@25919
   497
wenzelm@60758
   498
text\<open>Now we replace the case analysis rule by a more conventional one:
wenzelm@60758
   499
whether an integer is negative or not.\<close>
haftmann@25919
   500
wenzelm@60758
   501
text\<open>This version is symmetric in the two subgoals.\<close>
lp15@59613
   502
theorem int_cases2 [case_names nonneg nonpos, cases type: int]:
lp15@59613
   503
  "\<lbrakk>!! n. z = int n \<Longrightarrow> P;  !! n. z = - (int n) \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
lp15@59613
   504
apply (cases "z < 0")
lp15@59613
   505
apply (auto simp add: linorder_not_less dest!: negD nat_0_le [THEN sym])
lp15@59613
   506
done
lp15@59613
   507
wenzelm@60758
   508
text\<open>This is the default, with a negative case.\<close>
wenzelm@42676
   509
theorem int_cases [case_names nonneg neg, cases type: int]:
lp15@59613
   510
  "[|!! n. z = int n ==> P;  !! n. z = - (int (Suc n)) ==> P |] ==> P"
wenzelm@42676
   511
apply (cases "z < 0")
wenzelm@42676
   512
apply (blast dest!: negD)
haftmann@25919
   513
apply (simp add: linorder_not_less del: of_nat_Suc)
haftmann@25919
   514
apply auto
haftmann@25919
   515
apply (blast dest: nat_0_le [THEN sym])
haftmann@25919
   516
done
haftmann@25919
   517
haftmann@60868
   518
lemma int_cases3 [case_names zero pos neg]:
haftmann@60868
   519
  fixes k :: int
haftmann@60868
   520
  assumes "k = 0 \<Longrightarrow> P" and "\<And>n. k = int n \<Longrightarrow> n > 0 \<Longrightarrow> P"
haftmann@60868
   521
    and "\<And>n. k = - int n \<Longrightarrow> n > 0 \<Longrightarrow> P" 
haftmann@60868
   522
  shows "P"
haftmann@60868
   523
proof (cases k "0::int" rule: linorder_cases)
haftmann@60868
   524
  case equal with assms(1) show P by simp
haftmann@60868
   525
next
haftmann@60868
   526
  case greater
haftmann@60868
   527
  then have "nat k > 0" by simp
haftmann@60868
   528
  moreover from this have "k = int (nat k)" by auto
haftmann@60868
   529
  ultimately show P using assms(2) by blast
haftmann@60868
   530
next
haftmann@60868
   531
  case less
haftmann@60868
   532
  then have "nat (- k) > 0" by simp
haftmann@60868
   533
  moreover from this have "k = - int (nat (- k))" by auto
haftmann@60868
   534
  ultimately show P using assms(3) by blast
haftmann@60868
   535
qed
haftmann@60868
   536
wenzelm@42676
   537
theorem int_of_nat_induct [case_names nonneg neg, induct type: int]:
huffman@44709
   538
     "[|!! n. P (int n);  !!n. P (- (int (Suc n))) |] ==> P z"
wenzelm@42676
   539
  by (cases z) auto
haftmann@25919
   540
huffman@47207
   541
lemma nonneg_int_cases:
huffman@47207
   542
  assumes "0 \<le> k" obtains n where "k = int n"
haftmann@54489
   543
  using assms by (rule nonneg_eq_int)
huffman@47207
   544
huffman@47108
   545
lemma Let_numeral [simp]: "Let (numeral v) f = f (numeral v)"
wenzelm@60758
   546
  -- \<open>Unfold all @{text let}s involving constants\<close>
wenzelm@60758
   547
  by (fact Let_numeral) -- \<open>FIXME drop\<close>
haftmann@37767
   548
haftmann@54489
   549
lemma Let_neg_numeral [simp]: "Let (- numeral v) f = f (- numeral v)"
wenzelm@60758
   550
  -- \<open>Unfold all @{text let}s involving constants\<close>
wenzelm@60758
   551
  by (fact Let_neg_numeral) -- \<open>FIXME drop\<close>
haftmann@25919
   552
wenzelm@60758
   553
text \<open>Unfold @{text min} and @{text max} on numerals.\<close>
huffman@28958
   554
huffman@47108
   555
lemmas max_number_of [simp] =
huffman@47108
   556
  max_def [of "numeral u" "numeral v"]
haftmann@54489
   557
  max_def [of "numeral u" "- numeral v"]
haftmann@54489
   558
  max_def [of "- numeral u" "numeral v"]
haftmann@54489
   559
  max_def [of "- numeral u" "- numeral v"] for u v
huffman@28958
   560
huffman@47108
   561
lemmas min_number_of [simp] =
huffman@47108
   562
  min_def [of "numeral u" "numeral v"]
haftmann@54489
   563
  min_def [of "numeral u" "- numeral v"]
haftmann@54489
   564
  min_def [of "- numeral u" "numeral v"]
haftmann@54489
   565
  min_def [of "- numeral u" "- numeral v"] for u v
huffman@26075
   566
haftmann@25919
   567
wenzelm@60758
   568
subsubsection \<open>Binary comparisons\<close>
huffman@28958
   569
wenzelm@60758
   570
text \<open>Preliminaries\<close>
huffman@28958
   571
lp15@60162
   572
lemma le_imp_0_less:
huffman@28958
   573
  assumes le: "0 \<le> z"
huffman@28958
   574
  shows "(0::int) < 1 + z"
huffman@28958
   575
proof -
huffman@28958
   576
  have "0 \<le> z" by fact
huffman@47108
   577
  also have "... < z + 1" by (rule less_add_one)
haftmann@57514
   578
  also have "... = 1 + z" by (simp add: ac_simps)
huffman@28958
   579
  finally show "0 < 1 + z" .
huffman@28958
   580
qed
huffman@28958
   581
huffman@28958
   582
lemma odd_less_0_iff:
huffman@28958
   583
  "(1 + z + z < 0) = (z < (0::int))"
wenzelm@42676
   584
proof (cases z)
huffman@28958
   585
  case (nonneg n)
haftmann@57512
   586
  thus ?thesis by (simp add: linorder_not_less add.assoc add_increasing
lp15@60162
   587
                             le_imp_0_less [THEN order_less_imp_le])
huffman@28958
   588
next
huffman@28958
   589
  case (neg n)
huffman@30079
   590
  thus ?thesis by (simp del: of_nat_Suc of_nat_add of_nat_1
huffman@30079
   591
    add: algebra_simps of_nat_1 [where 'a=int, symmetric] of_nat_add [symmetric])
huffman@28958
   592
qed
huffman@28958
   593
wenzelm@60758
   594
subsubsection \<open>Comparisons, for Ordered Rings\<close>
haftmann@25919
   595
haftmann@25919
   596
lemmas double_eq_0_iff = double_zero
haftmann@25919
   597
haftmann@25919
   598
lemma odd_nonzero:
haftmann@33296
   599
  "1 + z + z \<noteq> (0::int)"
wenzelm@42676
   600
proof (cases z)
haftmann@25919
   601
  case (nonneg n)
lp15@60162
   602
  have le: "0 \<le> z+z" by (simp add: nonneg add_increasing)
haftmann@25919
   603
  thus ?thesis using  le_imp_0_less [OF le]
lp15@60162
   604
    by (auto simp add: add.assoc)
haftmann@25919
   605
next
haftmann@25919
   606
  case (neg n)
haftmann@25919
   607
  show ?thesis
haftmann@25919
   608
  proof
haftmann@25919
   609
    assume eq: "1 + z + z = 0"
huffman@44709
   610
    have "(0::int) < 1 + (int n + int n)"
lp15@60162
   611
      by (simp add: le_imp_0_less add_increasing)
lp15@60162
   612
    also have "... = - (1 + z + z)"
lp15@60162
   613
      by (simp add: neg add.assoc [symmetric])
lp15@60162
   614
    also have "... = 0" by (simp add: eq)
haftmann@25919
   615
    finally have "0<0" ..
haftmann@25919
   616
    thus False by blast
haftmann@25919
   617
  qed
haftmann@25919
   618
qed
haftmann@25919
   619
haftmann@30652
   620
wenzelm@60758
   621
subsection \<open>The Set of Integers\<close>
haftmann@25919
   622
haftmann@25919
   623
context ring_1
haftmann@25919
   624
begin
haftmann@25919
   625
haftmann@30652
   626
definition Ints  :: "'a set" where
haftmann@37767
   627
  "Ints = range of_int"
haftmann@25919
   628
haftmann@25919
   629
notation (xsymbols)
haftmann@25919
   630
  Ints  ("\<int>")
haftmann@25919
   631
huffman@35634
   632
lemma Ints_of_int [simp]: "of_int z \<in> \<int>"
huffman@35634
   633
  by (simp add: Ints_def)
huffman@35634
   634
huffman@35634
   635
lemma Ints_of_nat [simp]: "of_nat n \<in> \<int>"
huffman@45533
   636
  using Ints_of_int [of "of_nat n"] by simp
huffman@35634
   637
haftmann@25919
   638
lemma Ints_0 [simp]: "0 \<in> \<int>"
huffman@45533
   639
  using Ints_of_int [of "0"] by simp
haftmann@25919
   640
haftmann@25919
   641
lemma Ints_1 [simp]: "1 \<in> \<int>"
huffman@45533
   642
  using Ints_of_int [of "1"] by simp
haftmann@25919
   643
haftmann@25919
   644
lemma Ints_add [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a + b \<in> \<int>"
haftmann@25919
   645
apply (auto simp add: Ints_def)
haftmann@25919
   646
apply (rule range_eqI)
haftmann@25919
   647
apply (rule of_int_add [symmetric])
haftmann@25919
   648
done
haftmann@25919
   649
haftmann@25919
   650
lemma Ints_minus [simp]: "a \<in> \<int> \<Longrightarrow> -a \<in> \<int>"
haftmann@25919
   651
apply (auto simp add: Ints_def)
haftmann@25919
   652
apply (rule range_eqI)
haftmann@25919
   653
apply (rule of_int_minus [symmetric])
haftmann@25919
   654
done
haftmann@25919
   655
huffman@35634
   656
lemma Ints_diff [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a - b \<in> \<int>"
huffman@35634
   657
apply (auto simp add: Ints_def)
huffman@35634
   658
apply (rule range_eqI)
huffman@35634
   659
apply (rule of_int_diff [symmetric])
huffman@35634
   660
done
huffman@35634
   661
haftmann@25919
   662
lemma Ints_mult [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a * b \<in> \<int>"
haftmann@25919
   663
apply (auto simp add: Ints_def)
haftmann@25919
   664
apply (rule range_eqI)
haftmann@25919
   665
apply (rule of_int_mult [symmetric])
haftmann@25919
   666
done
haftmann@25919
   667
huffman@35634
   668
lemma Ints_power [simp]: "a \<in> \<int> \<Longrightarrow> a ^ n \<in> \<int>"
huffman@35634
   669
by (induct n) simp_all
huffman@35634
   670
haftmann@25919
   671
lemma Ints_cases [cases set: Ints]:
haftmann@25919
   672
  assumes "q \<in> \<int>"
haftmann@25919
   673
  obtains (of_int) z where "q = of_int z"
haftmann@25919
   674
  unfolding Ints_def
haftmann@25919
   675
proof -
wenzelm@60758
   676
  from \<open>q \<in> \<int>\<close> have "q \<in> range of_int" unfolding Ints_def .
haftmann@25919
   677
  then obtain z where "q = of_int z" ..
haftmann@25919
   678
  then show thesis ..
haftmann@25919
   679
qed
haftmann@25919
   680
haftmann@25919
   681
lemma Ints_induct [case_names of_int, induct set: Ints]:
haftmann@25919
   682
  "q \<in> \<int> \<Longrightarrow> (\<And>z. P (of_int z)) \<Longrightarrow> P q"
haftmann@25919
   683
  by (rule Ints_cases) auto
haftmann@25919
   684
haftmann@25919
   685
end
haftmann@25919
   686
wenzelm@60758
   687
text \<open>The premise involving @{term Ints} prevents @{term "a = 1/2"}.\<close>
haftmann@25919
   688
haftmann@25919
   689
lemma Ints_double_eq_0_iff:
haftmann@25919
   690
  assumes in_Ints: "a \<in> Ints"
haftmann@25919
   691
  shows "(a + a = 0) = (a = (0::'a::ring_char_0))"
haftmann@25919
   692
proof -
haftmann@25919
   693
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   694
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   695
  show ?thesis
haftmann@25919
   696
  proof
haftmann@25919
   697
    assume "a = 0"
haftmann@25919
   698
    thus "a + a = 0" by simp
haftmann@25919
   699
  next
haftmann@25919
   700
    assume eq: "a + a = 0"
haftmann@25919
   701
    hence "of_int (z + z) = (of_int 0 :: 'a)" by (simp add: a)
haftmann@25919
   702
    hence "z + z = 0" by (simp only: of_int_eq_iff)
haftmann@25919
   703
    hence "z = 0" by (simp only: double_eq_0_iff)
haftmann@25919
   704
    thus "a = 0" by (simp add: a)
haftmann@25919
   705
  qed
haftmann@25919
   706
qed
haftmann@25919
   707
haftmann@25919
   708
lemma Ints_odd_nonzero:
haftmann@25919
   709
  assumes in_Ints: "a \<in> Ints"
haftmann@25919
   710
  shows "1 + a + a \<noteq> (0::'a::ring_char_0)"
haftmann@25919
   711
proof -
haftmann@25919
   712
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   713
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   714
  show ?thesis
haftmann@25919
   715
  proof
haftmann@25919
   716
    assume eq: "1 + a + a = 0"
haftmann@25919
   717
    hence "of_int (1 + z + z) = (of_int 0 :: 'a)" by (simp add: a)
haftmann@25919
   718
    hence "1 + z + z = 0" by (simp only: of_int_eq_iff)
haftmann@25919
   719
    with odd_nonzero show False by blast
haftmann@25919
   720
  qed
lp15@60162
   721
qed
haftmann@25919
   722
huffman@47108
   723
lemma Nats_numeral [simp]: "numeral w \<in> Nats"
huffman@47108
   724
  using of_nat_in_Nats [of "numeral w"] by simp
huffman@35634
   725
lp15@60162
   726
lemma Ints_odd_less_0:
haftmann@25919
   727
  assumes in_Ints: "a \<in> Ints"
haftmann@35028
   728
  shows "(1 + a + a < 0) = (a < (0::'a::linordered_idom))"
haftmann@25919
   729
proof -
haftmann@25919
   730
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   731
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   732
  hence "((1::'a) + a + a < 0) = (of_int (1 + z + z) < (of_int 0 :: 'a))"
haftmann@25919
   733
    by (simp add: a)
huffman@45532
   734
  also have "... = (z < 0)" by (simp only: of_int_less_iff odd_less_0_iff)
haftmann@25919
   735
  also have "... = (a < 0)" by (simp add: a)
haftmann@25919
   736
  finally show ?thesis .
haftmann@25919
   737
qed
haftmann@25919
   738
haftmann@25919
   739
wenzelm@60758
   740
subsection \<open>@{term setsum} and @{term setprod}\<close>
haftmann@25919
   741
haftmann@25919
   742
lemma of_nat_setsum: "of_nat (setsum f A) = (\<Sum>x\<in>A. of_nat(f x))"
haftmann@25919
   743
  apply (cases "finite A")
haftmann@25919
   744
  apply (erule finite_induct, auto)
haftmann@25919
   745
  done
haftmann@25919
   746
haftmann@25919
   747
lemma of_int_setsum: "of_int (setsum f A) = (\<Sum>x\<in>A. of_int(f x))"
haftmann@25919
   748
  apply (cases "finite A")
haftmann@25919
   749
  apply (erule finite_induct, auto)
haftmann@25919
   750
  done
haftmann@25919
   751
haftmann@25919
   752
lemma of_nat_setprod: "of_nat (setprod f A) = (\<Prod>x\<in>A. of_nat(f x))"
haftmann@25919
   753
  apply (cases "finite A")
haftmann@25919
   754
  apply (erule finite_induct, auto simp add: of_nat_mult)
haftmann@25919
   755
  done
haftmann@25919
   756
haftmann@25919
   757
lemma of_int_setprod: "of_int (setprod f A) = (\<Prod>x\<in>A. of_int(f x))"
haftmann@25919
   758
  apply (cases "finite A")
haftmann@25919
   759
  apply (erule finite_induct, auto)
haftmann@25919
   760
  done
haftmann@25919
   761
haftmann@25919
   762
lemmas int_setsum = of_nat_setsum [where 'a=int]
haftmann@25919
   763
lemmas int_setprod = of_nat_setprod [where 'a=int]
haftmann@25919
   764
haftmann@25919
   765
wenzelm@60758
   766
text \<open>Legacy theorems\<close>
haftmann@25919
   767
haftmann@25919
   768
lemmas zle_int = of_nat_le_iff [where 'a=int]
haftmann@25919
   769
lemmas int_int_eq = of_nat_eq_iff [where 'a=int]
huffman@47108
   770
lemmas numeral_1_eq_1 = numeral_One
haftmann@25919
   771
wenzelm@60758
   772
subsection \<open>Setting up simplification procedures\<close>
huffman@30802
   773
haftmann@54249
   774
lemmas of_int_simps =
haftmann@54249
   775
  of_int_0 of_int_1 of_int_add of_int_mult
haftmann@54249
   776
wenzelm@48891
   777
ML_file "Tools/int_arith.ML"
wenzelm@60758
   778
declaration \<open>K Int_Arith.setup\<close>
haftmann@25919
   779
huffman@47108
   780
simproc_setup fast_arith ("(m::'a::linordered_idom) < n" |
huffman@47108
   781
  "(m::'a::linordered_idom) <= n" |
huffman@47108
   782
  "(m::'a::linordered_idom) = n") =
wenzelm@60758
   783
  \<open>fn _ => fn ss => fn ct => Lin_Arith.simproc ss (Thm.term_of ct)\<close>
wenzelm@43595
   784
haftmann@25919
   785
wenzelm@60758
   786
subsection\<open>More Inequality Reasoning\<close>
haftmann@25919
   787
haftmann@25919
   788
lemma zless_add1_eq: "(w < z + (1::int)) = (w<z | w=z)"
haftmann@25919
   789
by arith
haftmann@25919
   790
haftmann@25919
   791
lemma add1_zle_eq: "(w + (1::int) \<le> z) = (w<z)"
haftmann@25919
   792
by arith
haftmann@25919
   793
haftmann@25919
   794
lemma zle_diff1_eq [simp]: "(w \<le> z - (1::int)) = (w<z)"
haftmann@25919
   795
by arith
haftmann@25919
   796
haftmann@25919
   797
lemma zle_add1_eq_le [simp]: "(w < z + (1::int)) = (w\<le>z)"
haftmann@25919
   798
by arith
haftmann@25919
   799
haftmann@25919
   800
lemma int_one_le_iff_zero_less: "((1::int) \<le> z) = (0 < z)"
haftmann@25919
   801
by arith
haftmann@25919
   802
haftmann@25919
   803
wenzelm@60758
   804
subsection\<open>The functions @{term nat} and @{term int}\<close>
haftmann@25919
   805
wenzelm@60758
   806
text\<open>Simplify the term @{term "w + - z"}\<close>
haftmann@25919
   807
haftmann@25919
   808
lemma one_less_nat_eq [simp]: "(Suc 0 < nat z) = (1 < z)"
lp15@60162
   809
  using zless_nat_conj [of 1 z] by auto
haftmann@25919
   810
wenzelm@60758
   811
text\<open>This simplifies expressions of the form @{term "int n = z"} where
wenzelm@60758
   812
      z is an integer literal.\<close>
huffman@47108
   813
lemmas int_eq_iff_numeral [simp] = int_eq_iff [of _ "numeral v"] for v
haftmann@25919
   814
haftmann@25919
   815
lemma split_nat [arith_split]:
huffman@44709
   816
  "P(nat(i::int)) = ((\<forall>n. i = int n \<longrightarrow> P n) & (i < 0 \<longrightarrow> P 0))"
haftmann@25919
   817
  (is "?P = (?L & ?R)")
haftmann@25919
   818
proof (cases "i < 0")
haftmann@25919
   819
  case True thus ?thesis by auto
haftmann@25919
   820
next
haftmann@25919
   821
  case False
haftmann@25919
   822
  have "?P = ?L"
haftmann@25919
   823
  proof
haftmann@25919
   824
    assume ?P thus ?L using False by clarsimp
haftmann@25919
   825
  next
haftmann@25919
   826
    assume ?L thus ?P using False by simp
haftmann@25919
   827
  qed
haftmann@25919
   828
  with False show ?thesis by simp
haftmann@25919
   829
qed
haftmann@25919
   830
hoelzl@59000
   831
lemma nat_abs_int_diff: "nat \<bar>int a - int b\<bar> = (if a \<le> b then b - a else a - b)"
hoelzl@59000
   832
  by auto
hoelzl@59000
   833
hoelzl@59000
   834
lemma nat_int_add: "nat (int a + int b) = a + b"
hoelzl@59000
   835
  by auto
hoelzl@59000
   836
haftmann@25919
   837
context ring_1
haftmann@25919
   838
begin
haftmann@25919
   839
blanchet@33056
   840
lemma of_int_of_nat [nitpick_simp]:
haftmann@25919
   841
  "of_int k = (if k < 0 then - of_nat (nat (- k)) else of_nat (nat k))"
haftmann@25919
   842
proof (cases "k < 0")
haftmann@25919
   843
  case True then have "0 \<le> - k" by simp
haftmann@25919
   844
  then have "of_nat (nat (- k)) = of_int (- k)" by (rule of_nat_nat)
haftmann@25919
   845
  with True show ?thesis by simp
haftmann@25919
   846
next
haftmann@25919
   847
  case False then show ?thesis by (simp add: not_less of_nat_nat)
haftmann@25919
   848
qed
haftmann@25919
   849
haftmann@25919
   850
end
haftmann@25919
   851
haftmann@25919
   852
lemma nat_mult_distrib:
haftmann@25919
   853
  fixes z z' :: int
haftmann@25919
   854
  assumes "0 \<le> z"
haftmann@25919
   855
  shows "nat (z * z') = nat z * nat z'"
haftmann@25919
   856
proof (cases "0 \<le> z'")
haftmann@25919
   857
  case False with assms have "z * z' \<le> 0"
haftmann@25919
   858
    by (simp add: not_le mult_le_0_iff)
haftmann@25919
   859
  then have "nat (z * z') = 0" by simp
haftmann@25919
   860
  moreover from False have "nat z' = 0" by simp
haftmann@25919
   861
  ultimately show ?thesis by simp
haftmann@25919
   862
next
haftmann@25919
   863
  case True with assms have ge_0: "z * z' \<ge> 0" by (simp add: zero_le_mult_iff)
haftmann@25919
   864
  show ?thesis
haftmann@25919
   865
    by (rule injD [of "of_nat :: nat \<Rightarrow> int", OF inj_of_nat])
haftmann@25919
   866
      (simp only: of_nat_mult of_nat_nat [OF True]
haftmann@25919
   867
         of_nat_nat [OF assms] of_nat_nat [OF ge_0], simp)
haftmann@25919
   868
qed
haftmann@25919
   869
haftmann@25919
   870
lemma nat_mult_distrib_neg: "z \<le> (0::int) ==> nat(z*z') = nat(-z) * nat(-z')"
haftmann@25919
   871
apply (rule trans)
haftmann@25919
   872
apply (rule_tac [2] nat_mult_distrib, auto)
haftmann@25919
   873
done
haftmann@25919
   874
haftmann@25919
   875
lemma nat_abs_mult_distrib: "nat (abs (w * z)) = nat (abs w) * nat (abs z)"
haftmann@25919
   876
apply (cases "z=0 | w=0")
lp15@60162
   877
apply (auto simp add: abs_if nat_mult_distrib [symmetric]
haftmann@25919
   878
                      nat_mult_distrib_neg [symmetric] mult_less_0_iff)
haftmann@25919
   879
done
haftmann@25919
   880
haftmann@60570
   881
lemma int_in_range_abs [simp]:
haftmann@60570
   882
  "int n \<in> range abs"
haftmann@60570
   883
proof (rule range_eqI)
haftmann@60570
   884
  show "int n = \<bar>int n\<bar>"
haftmann@60570
   885
    by simp
haftmann@60570
   886
qed
haftmann@60570
   887
haftmann@60570
   888
lemma range_abs_Nats [simp]:
haftmann@60570
   889
  "range abs = (\<nat> :: int set)"
haftmann@60570
   890
proof -
haftmann@60570
   891
  have "\<bar>k\<bar> \<in> \<nat>" for k :: int
haftmann@60570
   892
    by (cases k) simp_all
haftmann@60570
   893
  moreover have "k \<in> range abs" if "k \<in> \<nat>" for k :: int
haftmann@60570
   894
    using that by induct simp
haftmann@60570
   895
  ultimately show ?thesis by blast
haftmann@60570
   896
qed  
haftmann@60570
   897
huffman@47207
   898
lemma Suc_nat_eq_nat_zadd1: "(0::int) <= z ==> Suc (nat z) = nat (1 + z)"
huffman@47207
   899
apply (rule sym)
huffman@47207
   900
apply (simp add: nat_eq_iff)
huffman@47207
   901
done
huffman@47207
   902
huffman@47207
   903
lemma diff_nat_eq_if:
lp15@60162
   904
     "nat z - nat z' =
lp15@60162
   905
        (if z' < 0 then nat z
lp15@60162
   906
         else let d = z-z' in
huffman@47207
   907
              if d < 0 then 0 else nat d)"
huffman@47207
   908
by (simp add: Let_def nat_diff_distrib [symmetric])
huffman@47207
   909
huffman@47207
   910
lemma nat_numeral_diff_1 [simp]:
huffman@47207
   911
  "numeral v - (1::nat) = nat (numeral v - 1)"
huffman@47207
   912
  using diff_nat_numeral [of v Num.One] by simp
huffman@47207
   913
haftmann@25919
   914
haftmann@25919
   915
subsection "Induction principles for int"
haftmann@25919
   916
wenzelm@60758
   917
text\<open>Well-founded segments of the integers\<close>
haftmann@25919
   918
haftmann@25919
   919
definition
haftmann@25919
   920
  int_ge_less_than  ::  "int => (int * int) set"
haftmann@25919
   921
where
haftmann@25919
   922
  "int_ge_less_than d = {(z',z). d \<le> z' & z' < z}"
haftmann@25919
   923
haftmann@25919
   924
theorem wf_int_ge_less_than: "wf (int_ge_less_than d)"
haftmann@25919
   925
proof -
haftmann@25919
   926
  have "int_ge_less_than d \<subseteq> measure (%z. nat (z-d))"
haftmann@25919
   927
    by (auto simp add: int_ge_less_than_def)
lp15@60162
   928
  thus ?thesis
lp15@60162
   929
    by (rule wf_subset [OF wf_measure])
haftmann@25919
   930
qed
haftmann@25919
   931
wenzelm@60758
   932
text\<open>This variant looks odd, but is typical of the relations suggested
wenzelm@60758
   933
by RankFinder.\<close>
haftmann@25919
   934
haftmann@25919
   935
definition
haftmann@25919
   936
  int_ge_less_than2 ::  "int => (int * int) set"
haftmann@25919
   937
where
haftmann@25919
   938
  "int_ge_less_than2 d = {(z',z). d \<le> z & z' < z}"
haftmann@25919
   939
haftmann@25919
   940
theorem wf_int_ge_less_than2: "wf (int_ge_less_than2 d)"
haftmann@25919
   941
proof -
lp15@60162
   942
  have "int_ge_less_than2 d \<subseteq> measure (%z. nat (1+z-d))"
haftmann@25919
   943
    by (auto simp add: int_ge_less_than2_def)
lp15@60162
   944
  thus ?thesis
lp15@60162
   945
    by (rule wf_subset [OF wf_measure])
haftmann@25919
   946
qed
haftmann@25919
   947
haftmann@25919
   948
(* `set:int': dummy construction *)
haftmann@25919
   949
theorem int_ge_induct [case_names base step, induct set: int]:
haftmann@25919
   950
  fixes i :: int
haftmann@25919
   951
  assumes ge: "k \<le> i" and
haftmann@25919
   952
    base: "P k" and
haftmann@25919
   953
    step: "\<And>i. k \<le> i \<Longrightarrow> P i \<Longrightarrow> P (i + 1)"
haftmann@25919
   954
  shows "P i"
haftmann@25919
   955
proof -
wenzelm@42676
   956
  { fix n
wenzelm@42676
   957
    have "\<And>i::int. n = nat (i - k) \<Longrightarrow> k \<le> i \<Longrightarrow> P i"
haftmann@25919
   958
    proof (induct n)
haftmann@25919
   959
      case 0
haftmann@25919
   960
      hence "i = k" by arith
haftmann@25919
   961
      thus "P i" using base by simp
haftmann@25919
   962
    next
haftmann@25919
   963
      case (Suc n)
haftmann@25919
   964
      then have "n = nat((i - 1) - k)" by arith
haftmann@25919
   965
      moreover
haftmann@25919
   966
      have ki1: "k \<le> i - 1" using Suc.prems by arith
haftmann@25919
   967
      ultimately
wenzelm@42676
   968
      have "P (i - 1)" by (rule Suc.hyps)
wenzelm@42676
   969
      from step [OF ki1 this] show ?case by simp
haftmann@25919
   970
    qed
haftmann@25919
   971
  }
haftmann@25919
   972
  with ge show ?thesis by fast
haftmann@25919
   973
qed
haftmann@25919
   974
haftmann@25928
   975
(* `set:int': dummy construction *)
haftmann@25928
   976
theorem int_gr_induct [case_names base step, induct set: int]:
haftmann@25919
   977
  assumes gr: "k < (i::int)" and
haftmann@25919
   978
        base: "P(k+1)" and
haftmann@25919
   979
        step: "\<And>i. \<lbrakk>k < i; P i\<rbrakk> \<Longrightarrow> P(i+1)"
haftmann@25919
   980
  shows "P i"
haftmann@25919
   981
apply(rule int_ge_induct[of "k + 1"])
haftmann@25919
   982
  using gr apply arith
haftmann@25919
   983
 apply(rule base)
haftmann@25919
   984
apply (rule step, simp+)
haftmann@25919
   985
done
haftmann@25919
   986
wenzelm@42676
   987
theorem int_le_induct [consumes 1, case_names base step]:
haftmann@25919
   988
  assumes le: "i \<le> (k::int)" and
haftmann@25919
   989
        base: "P(k)" and
haftmann@25919
   990
        step: "\<And>i. \<lbrakk>i \<le> k; P i\<rbrakk> \<Longrightarrow> P(i - 1)"
haftmann@25919
   991
  shows "P i"
haftmann@25919
   992
proof -
wenzelm@42676
   993
  { fix n
wenzelm@42676
   994
    have "\<And>i::int. n = nat(k-i) \<Longrightarrow> i \<le> k \<Longrightarrow> P i"
haftmann@25919
   995
    proof (induct n)
haftmann@25919
   996
      case 0
haftmann@25919
   997
      hence "i = k" by arith
haftmann@25919
   998
      thus "P i" using base by simp
haftmann@25919
   999
    next
haftmann@25919
  1000
      case (Suc n)
wenzelm@42676
  1001
      hence "n = nat (k - (i + 1))" by arith
haftmann@25919
  1002
      moreover
haftmann@25919
  1003
      have ki1: "i + 1 \<le> k" using Suc.prems by arith
haftmann@25919
  1004
      ultimately
wenzelm@42676
  1005
      have "P (i + 1)" by(rule Suc.hyps)
haftmann@25919
  1006
      from step[OF ki1 this] show ?case by simp
haftmann@25919
  1007
    qed
haftmann@25919
  1008
  }
haftmann@25919
  1009
  with le show ?thesis by fast
haftmann@25919
  1010
qed
haftmann@25919
  1011
wenzelm@42676
  1012
theorem int_less_induct [consumes 1, case_names base step]:
haftmann@25919
  1013
  assumes less: "(i::int) < k" and
haftmann@25919
  1014
        base: "P(k - 1)" and
haftmann@25919
  1015
        step: "\<And>i. \<lbrakk>i < k; P i\<rbrakk> \<Longrightarrow> P(i - 1)"
haftmann@25919
  1016
  shows "P i"
haftmann@25919
  1017
apply(rule int_le_induct[of _ "k - 1"])
haftmann@25919
  1018
  using less apply arith
haftmann@25919
  1019
 apply(rule base)
haftmann@25919
  1020
apply (rule step, simp+)
haftmann@25919
  1021
done
haftmann@25919
  1022
haftmann@36811
  1023
theorem int_induct [case_names base step1 step2]:
haftmann@36801
  1024
  fixes k :: int
haftmann@36801
  1025
  assumes base: "P k"
haftmann@36801
  1026
    and step1: "\<And>i. k \<le> i \<Longrightarrow> P i \<Longrightarrow> P (i + 1)"
haftmann@36801
  1027
    and step2: "\<And>i. k \<ge> i \<Longrightarrow> P i \<Longrightarrow> P (i - 1)"
haftmann@36801
  1028
  shows "P i"
haftmann@36801
  1029
proof -
haftmann@36801
  1030
  have "i \<le> k \<or> i \<ge> k" by arith
wenzelm@42676
  1031
  then show ?thesis
wenzelm@42676
  1032
  proof
wenzelm@42676
  1033
    assume "i \<ge> k"
wenzelm@42676
  1034
    then show ?thesis using base
haftmann@36801
  1035
      by (rule int_ge_induct) (fact step1)
haftmann@36801
  1036
  next
wenzelm@42676
  1037
    assume "i \<le> k"
wenzelm@42676
  1038
    then show ?thesis using base
haftmann@36801
  1039
      by (rule int_le_induct) (fact step2)
haftmann@36801
  1040
  qed
haftmann@36801
  1041
qed
haftmann@36801
  1042
wenzelm@60758
  1043
subsection\<open>Intermediate value theorems\<close>
haftmann@25919
  1044
haftmann@25919
  1045
lemma int_val_lemma:
lp15@60162
  1046
     "(\<forall>i<n::nat. abs(f(i+1) - f i) \<le> 1) -->
haftmann@25919
  1047
      f 0 \<le> k --> k \<le> f n --> (\<exists>i \<le> n. f i = (k::int))"
huffman@30079
  1048
unfolding One_nat_def
wenzelm@42676
  1049
apply (induct n)
wenzelm@42676
  1050
apply simp
haftmann@25919
  1051
apply (intro strip)
haftmann@25919
  1052
apply (erule impE, simp)
haftmann@25919
  1053
apply (erule_tac x = n in allE, simp)
huffman@30079
  1054
apply (case_tac "k = f (Suc n)")
haftmann@27106
  1055
apply force
haftmann@25919
  1056
apply (erule impE)
haftmann@25919
  1057
 apply (simp add: abs_if split add: split_if_asm)
haftmann@25919
  1058
apply (blast intro: le_SucI)
haftmann@25919
  1059
done
haftmann@25919
  1060
haftmann@25919
  1061
lemmas nat0_intermed_int_val = int_val_lemma [rule_format (no_asm)]
haftmann@25919
  1062
haftmann@25919
  1063
lemma nat_intermed_int_val:
lp15@60162
  1064
     "[| \<forall>i. m \<le> i & i < n --> abs(f(i + 1::nat) - f i) \<le> 1; m < n;
haftmann@25919
  1065
         f m \<le> k; k \<le> f n |] ==> ? i. m \<le> i & i \<le> n & f i = (k::int)"
lp15@60162
  1066
apply (cut_tac n = "n-m" and f = "%i. f (i+m) " and k = k
haftmann@25919
  1067
       in int_val_lemma)
huffman@30079
  1068
unfolding One_nat_def
haftmann@25919
  1069
apply simp
haftmann@25919
  1070
apply (erule exE)
haftmann@25919
  1071
apply (rule_tac x = "i+m" in exI, arith)
haftmann@25919
  1072
done
haftmann@25919
  1073
haftmann@25919
  1074
wenzelm@60758
  1075
subsection\<open>Products and 1, by T. M. Rasmussen\<close>
haftmann@25919
  1076
haftmann@25919
  1077
lemma zabs_less_one_iff [simp]: "(\<bar>z\<bar> < 1) = (z = (0::int))"
haftmann@25919
  1078
by arith
haftmann@25919
  1079
paulson@34055
  1080
lemma abs_zmult_eq_1:
paulson@34055
  1081
  assumes mn: "\<bar>m * n\<bar> = 1"
paulson@34055
  1082
  shows "\<bar>m\<bar> = (1::int)"
paulson@34055
  1083
proof -
paulson@34055
  1084
  have 0: "m \<noteq> 0 & n \<noteq> 0" using mn
paulson@34055
  1085
    by auto
paulson@34055
  1086
  have "~ (2 \<le> \<bar>m\<bar>)"
paulson@34055
  1087
  proof
paulson@34055
  1088
    assume "2 \<le> \<bar>m\<bar>"
paulson@34055
  1089
    hence "2*\<bar>n\<bar> \<le> \<bar>m\<bar>*\<bar>n\<bar>"
lp15@60162
  1090
      by (simp add: mult_mono 0)
lp15@60162
  1091
    also have "... = \<bar>m*n\<bar>"
paulson@34055
  1092
      by (simp add: abs_mult)
paulson@34055
  1093
    also have "... = 1"
paulson@34055
  1094
      by (simp add: mn)
paulson@34055
  1095
    finally have "2*\<bar>n\<bar> \<le> 1" .
paulson@34055
  1096
    thus "False" using 0
huffman@47108
  1097
      by arith
paulson@34055
  1098
  qed
paulson@34055
  1099
  thus ?thesis using 0
paulson@34055
  1100
    by auto
paulson@34055
  1101
qed
haftmann@25919
  1102
haftmann@25919
  1103
lemma pos_zmult_eq_1_iff_lemma: "(m * n = 1) ==> m = (1::int) | m = -1"
haftmann@25919
  1104
by (insert abs_zmult_eq_1 [of m n], arith)
haftmann@25919
  1105
boehmes@35815
  1106
lemma pos_zmult_eq_1_iff:
boehmes@35815
  1107
  assumes "0 < (m::int)" shows "(m * n = 1) = (m = 1 & n = 1)"
boehmes@35815
  1108
proof -
boehmes@35815
  1109
  from assms have "m * n = 1 ==> m = 1" by (auto dest: pos_zmult_eq_1_iff_lemma)
boehmes@35815
  1110
  thus ?thesis by (auto dest: pos_zmult_eq_1_iff_lemma)
boehmes@35815
  1111
qed
haftmann@25919
  1112
haftmann@25919
  1113
lemma zmult_eq_1_iff: "(m*n = (1::int)) = ((m = 1 & n = 1) | (m = -1 & n = -1))"
lp15@60162
  1114
apply (rule iffI)
haftmann@25919
  1115
 apply (frule pos_zmult_eq_1_iff_lemma)
lp15@60162
  1116
 apply (simp add: mult.commute [of m])
lp15@60162
  1117
 apply (frule pos_zmult_eq_1_iff_lemma, auto)
haftmann@25919
  1118
done
haftmann@25919
  1119
haftmann@33296
  1120
lemma infinite_UNIV_int: "\<not> finite (UNIV::int set)"
haftmann@25919
  1121
proof
haftmann@33296
  1122
  assume "finite (UNIV::int set)"
haftmann@33296
  1123
  moreover have "inj (\<lambda>i\<Colon>int. 2 * i)"
haftmann@33296
  1124
    by (rule injI) simp
haftmann@33296
  1125
  ultimately have "surj (\<lambda>i\<Colon>int. 2 * i)"
haftmann@33296
  1126
    by (rule finite_UNIV_inj_surj)
haftmann@33296
  1127
  then obtain i :: int where "1 = 2 * i" by (rule surjE)
haftmann@33296
  1128
  then show False by (simp add: pos_zmult_eq_1_iff)
haftmann@25919
  1129
qed
haftmann@25919
  1130
haftmann@25919
  1131
wenzelm@60758
  1132
subsection \<open>Further theorems on numerals\<close>
haftmann@30652
  1133
wenzelm@60758
  1134
subsubsection\<open>Special Simplification for Constants\<close>
haftmann@30652
  1135
wenzelm@60758
  1136
text\<open>These distributive laws move literals inside sums and differences.\<close>
haftmann@30652
  1137
webertj@49962
  1138
lemmas distrib_right_numeral [simp] = distrib_right [of _ _ "numeral v"] for v
webertj@49962
  1139
lemmas distrib_left_numeral [simp] = distrib_left [of "numeral v"] for v
huffman@47108
  1140
lemmas left_diff_distrib_numeral [simp] = left_diff_distrib [of _ _ "numeral v"] for v
huffman@47108
  1141
lemmas right_diff_distrib_numeral [simp] = right_diff_distrib [of "numeral v"] for v
haftmann@30652
  1142
wenzelm@60758
  1143
text\<open>These are actually for fields, like real: but where else to put them?\<close>
haftmann@30652
  1144
huffman@47108
  1145
lemmas zero_less_divide_iff_numeral [simp, no_atp] = zero_less_divide_iff [of "numeral w"] for w
huffman@47108
  1146
lemmas divide_less_0_iff_numeral [simp, no_atp] = divide_less_0_iff [of "numeral w"] for w
huffman@47108
  1147
lemmas zero_le_divide_iff_numeral [simp, no_atp] = zero_le_divide_iff [of "numeral w"] for w
huffman@47108
  1148
lemmas divide_le_0_iff_numeral [simp, no_atp] = divide_le_0_iff [of "numeral w"] for w
haftmann@30652
  1149
haftmann@30652
  1150
wenzelm@60758
  1151
text \<open>Replaces @{text "inverse #nn"} by @{text "1/#nn"}.  It looks
wenzelm@60758
  1152
  strange, but then other simprocs simplify the quotient.\<close>
haftmann@30652
  1153
huffman@47108
  1154
lemmas inverse_eq_divide_numeral [simp] =
huffman@47108
  1155
  inverse_eq_divide [of "numeral w"] for w
huffman@47108
  1156
huffman@47108
  1157
lemmas inverse_eq_divide_neg_numeral [simp] =
haftmann@54489
  1158
  inverse_eq_divide [of "- numeral w"] for w
haftmann@30652
  1159
wenzelm@60758
  1160
text \<open>These laws simplify inequalities, moving unary minus from a term
wenzelm@60758
  1161
into the literal.\<close>
haftmann@30652
  1162
haftmann@54489
  1163
lemmas equation_minus_iff_numeral [no_atp] =
haftmann@54489
  1164
  equation_minus_iff [of "numeral v"] for v
huffman@47108
  1165
haftmann@54489
  1166
lemmas minus_equation_iff_numeral [no_atp] =
haftmann@54489
  1167
  minus_equation_iff [of _ "numeral v"] for v
huffman@47108
  1168
haftmann@54489
  1169
lemmas le_minus_iff_numeral [no_atp] =
haftmann@54489
  1170
  le_minus_iff [of "numeral v"] for v
haftmann@30652
  1171
haftmann@54489
  1172
lemmas minus_le_iff_numeral [no_atp] =
haftmann@54489
  1173
  minus_le_iff [of _ "numeral v"] for v
haftmann@30652
  1174
haftmann@54489
  1175
lemmas less_minus_iff_numeral [no_atp] =
haftmann@54489
  1176
  less_minus_iff [of "numeral v"] for v
haftmann@30652
  1177
haftmann@54489
  1178
lemmas minus_less_iff_numeral [no_atp] =
haftmann@54489
  1179
  minus_less_iff [of _ "numeral v"] for v
haftmann@30652
  1180
wenzelm@60758
  1181
-- \<open>FIXME maybe simproc\<close>
haftmann@30652
  1182
haftmann@30652
  1183
wenzelm@60758
  1184
text \<open>Cancellation of constant factors in comparisons (@{text "<"} and @{text "\<le>"})\<close>
haftmann@30652
  1185
huffman@47108
  1186
lemmas mult_less_cancel_left_numeral [simp, no_atp] = mult_less_cancel_left [of "numeral v"] for v
huffman@47108
  1187
lemmas mult_less_cancel_right_numeral [simp, no_atp] = mult_less_cancel_right [of _ "numeral v"] for v
huffman@47108
  1188
lemmas mult_le_cancel_left_numeral [simp, no_atp] = mult_le_cancel_left [of "numeral v"] for v
huffman@47108
  1189
lemmas mult_le_cancel_right_numeral [simp, no_atp] = mult_le_cancel_right [of _ "numeral v"] for v
haftmann@30652
  1190
haftmann@30652
  1191
wenzelm@60758
  1192
text \<open>Multiplying out constant divisors in comparisons (@{text "<"}, @{text "\<le>"} and @{text "="})\<close>
haftmann@30652
  1193
huffman@47108
  1194
lemmas le_divide_eq_numeral1 [simp] =
huffman@47108
  1195
  pos_le_divide_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1196
  neg_le_divide_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1197
huffman@47108
  1198
lemmas divide_le_eq_numeral1 [simp] =
huffman@47108
  1199
  pos_divide_le_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1200
  neg_divide_le_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1201
huffman@47108
  1202
lemmas less_divide_eq_numeral1 [simp] =
huffman@47108
  1203
  pos_less_divide_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1204
  neg_less_divide_eq [of "- numeral w", OF neg_numeral_less_zero] for w
haftmann@30652
  1205
huffman@47108
  1206
lemmas divide_less_eq_numeral1 [simp] =
huffman@47108
  1207
  pos_divide_less_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1208
  neg_divide_less_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1209
huffman@47108
  1210
lemmas eq_divide_eq_numeral1 [simp] =
huffman@47108
  1211
  eq_divide_eq [of _ _ "numeral w"]
haftmann@54489
  1212
  eq_divide_eq [of _ _ "- numeral w"] for w
huffman@47108
  1213
huffman@47108
  1214
lemmas divide_eq_eq_numeral1 [simp] =
huffman@47108
  1215
  divide_eq_eq [of _ "numeral w"]
haftmann@54489
  1216
  divide_eq_eq [of _ "- numeral w"] for w
haftmann@54489
  1217
haftmann@30652
  1218
wenzelm@60758
  1219
subsubsection\<open>Optional Simplification Rules Involving Constants\<close>
haftmann@30652
  1220
wenzelm@60758
  1221
text\<open>Simplify quotients that are compared with a literal constant.\<close>
haftmann@30652
  1222
huffman@47108
  1223
lemmas le_divide_eq_numeral =
huffman@47108
  1224
  le_divide_eq [of "numeral w"]
haftmann@54489
  1225
  le_divide_eq [of "- numeral w"] for w
huffman@47108
  1226
huffman@47108
  1227
lemmas divide_le_eq_numeral =
huffman@47108
  1228
  divide_le_eq [of _ _ "numeral w"]
haftmann@54489
  1229
  divide_le_eq [of _ _ "- numeral w"] for w
huffman@47108
  1230
huffman@47108
  1231
lemmas less_divide_eq_numeral =
huffman@47108
  1232
  less_divide_eq [of "numeral w"]
haftmann@54489
  1233
  less_divide_eq [of "- numeral w"] for w
huffman@47108
  1234
huffman@47108
  1235
lemmas divide_less_eq_numeral =
huffman@47108
  1236
  divide_less_eq [of _ _ "numeral w"]
haftmann@54489
  1237
  divide_less_eq [of _ _ "- numeral w"] for w
huffman@47108
  1238
huffman@47108
  1239
lemmas eq_divide_eq_numeral =
huffman@47108
  1240
  eq_divide_eq [of "numeral w"]
haftmann@54489
  1241
  eq_divide_eq [of "- numeral w"] for w
huffman@47108
  1242
huffman@47108
  1243
lemmas divide_eq_eq_numeral =
huffman@47108
  1244
  divide_eq_eq [of _ _ "numeral w"]
haftmann@54489
  1245
  divide_eq_eq [of _ _ "- numeral w"] for w
haftmann@30652
  1246
haftmann@30652
  1247
wenzelm@60758
  1248
text\<open>Not good as automatic simprules because they cause case splits.\<close>
haftmann@30652
  1249
lemmas divide_const_simps =
huffman@47108
  1250
  le_divide_eq_numeral divide_le_eq_numeral less_divide_eq_numeral
huffman@47108
  1251
  divide_less_eq_numeral eq_divide_eq_numeral divide_eq_eq_numeral
haftmann@30652
  1252
  le_divide_eq_1 divide_le_eq_1 less_divide_eq_1 divide_less_eq_1
haftmann@30652
  1253
haftmann@30652
  1254
wenzelm@60758
  1255
subsection \<open>The divides relation\<close>
haftmann@33320
  1256
nipkow@33657
  1257
lemma zdvd_antisym_nonneg:
nipkow@33657
  1258
    "0 <= m ==> 0 <= n ==> m dvd n ==> n dvd m ==> m = (n::int)"
haftmann@33320
  1259
  apply (simp add: dvd_def, auto)
haftmann@57512
  1260
  apply (auto simp add: mult.assoc zero_le_mult_iff zmult_eq_1_iff)
haftmann@33320
  1261
  done
haftmann@33320
  1262
lp15@60162
  1263
lemma zdvd_antisym_abs: assumes "(a::int) dvd b" and "b dvd a"
haftmann@33320
  1264
  shows "\<bar>a\<bar> = \<bar>b\<bar>"
nipkow@33657
  1265
proof cases
nipkow@33657
  1266
  assume "a = 0" with assms show ?thesis by simp
nipkow@33657
  1267
next
nipkow@33657
  1268
  assume "a \<noteq> 0"
wenzelm@60758
  1269
  from \<open>a dvd b\<close> obtain k where k:"b = a*k" unfolding dvd_def by blast
wenzelm@60758
  1270
  from \<open>b dvd a\<close> obtain k' where k':"a = b*k'" unfolding dvd_def by blast
haftmann@33320
  1271
  from k k' have "a = a*k*k'" by simp
haftmann@33320
  1272
  with mult_cancel_left1[where c="a" and b="k*k'"]
wenzelm@60758
  1273
  have kk':"k*k' = 1" using \<open>a\<noteq>0\<close> by (simp add: mult.assoc)
haftmann@33320
  1274
  hence "k = 1 \<and> k' = 1 \<or> k = -1 \<and> k' = -1" by (simp add: zmult_eq_1_iff)
haftmann@33320
  1275
  thus ?thesis using k k' by auto
haftmann@33320
  1276
qed
haftmann@33320
  1277
haftmann@33320
  1278
lemma zdvd_zdiffD: "k dvd m - n ==> k dvd n ==> k dvd (m::int)"
lp15@60162
  1279
  using dvd_add_right_iff [of k "- n" m] by simp
haftmann@33320
  1280
haftmann@33320
  1281
lemma zdvd_reduce: "(k dvd n + k * m) = (k dvd (n::int))"
haftmann@58649
  1282
  using dvd_add_times_triv_right_iff [of k n m] by (simp add: ac_simps)
haftmann@33320
  1283
haftmann@33320
  1284
lemma dvd_imp_le_int:
haftmann@33320
  1285
  fixes d i :: int
haftmann@33320
  1286
  assumes "i \<noteq> 0" and "d dvd i"
haftmann@33320
  1287
  shows "\<bar>d\<bar> \<le> \<bar>i\<bar>"
haftmann@33320
  1288
proof -
wenzelm@60758
  1289
  from \<open>d dvd i\<close> obtain k where "i = d * k" ..
wenzelm@60758
  1290
  with \<open>i \<noteq> 0\<close> have "k \<noteq> 0" by auto
haftmann@33320
  1291
  then have "1 \<le> \<bar>k\<bar>" and "0 \<le> \<bar>d\<bar>" by auto
haftmann@33320
  1292
  then have "\<bar>d\<bar> * 1 \<le> \<bar>d\<bar> * \<bar>k\<bar>" by (rule mult_left_mono)
wenzelm@60758
  1293
  with \<open>i = d * k\<close> show ?thesis by (simp add: abs_mult)
haftmann@33320
  1294
qed
haftmann@33320
  1295
haftmann@33320
  1296
lemma zdvd_not_zless:
haftmann@33320
  1297
  fixes m n :: int
haftmann@33320
  1298
  assumes "0 < m" and "m < n"
haftmann@33320
  1299
  shows "\<not> n dvd m"
haftmann@33320
  1300
proof
haftmann@33320
  1301
  from assms have "0 < n" by auto
haftmann@33320
  1302
  assume "n dvd m" then obtain k where k: "m = n * k" ..
wenzelm@60758
  1303
  with \<open>0 < m\<close> have "0 < n * k" by auto
wenzelm@60758
  1304
  with \<open>0 < n\<close> have "0 < k" by (simp add: zero_less_mult_iff)
wenzelm@60758
  1305
  with k \<open>0 < n\<close> \<open>m < n\<close> have "n * k < n * 1" by simp
wenzelm@60758
  1306
  with \<open>0 < n\<close> \<open>0 < k\<close> show False unfolding mult_less_cancel_left by auto
haftmann@33320
  1307
qed
haftmann@33320
  1308
haftmann@33320
  1309
lemma zdvd_mult_cancel: assumes d:"k * m dvd k * n" and kz:"k \<noteq> (0::int)"
haftmann@33320
  1310
  shows "m dvd n"
haftmann@33320
  1311
proof-
haftmann@33320
  1312
  from d obtain h where h: "k*n = k*m * h" unfolding dvd_def by blast
haftmann@33320
  1313
  {assume "n \<noteq> m*h" hence "k* n \<noteq> k* (m*h)" using kz by simp
haftmann@57512
  1314
    with h have False by (simp add: mult.assoc)}
haftmann@33320
  1315
  hence "n = m * h" by blast
haftmann@33320
  1316
  thus ?thesis by simp
haftmann@33320
  1317
qed
haftmann@33320
  1318
haftmann@33320
  1319
theorem zdvd_int: "(x dvd y) = (int x dvd int y)"
haftmann@33320
  1320
proof -
haftmann@33320
  1321
  have "\<And>k. int y = int x * k \<Longrightarrow> x dvd y"
haftmann@33320
  1322
  proof -
haftmann@33320
  1323
    fix k
haftmann@33320
  1324
    assume A: "int y = int x * k"
wenzelm@42676
  1325
    then show "x dvd y"
wenzelm@42676
  1326
    proof (cases k)
wenzelm@42676
  1327
      case (nonneg n)
wenzelm@42676
  1328
      with A have "y = x * n" by (simp add: of_nat_mult [symmetric])
haftmann@33320
  1329
      then show ?thesis ..
haftmann@33320
  1330
    next
wenzelm@42676
  1331
      case (neg n)
wenzelm@42676
  1332
      with A have "int y = int x * (- int (Suc n))" by simp
haftmann@33320
  1333
      also have "\<dots> = - (int x * int (Suc n))" by (simp only: mult_minus_right)
haftmann@33320
  1334
      also have "\<dots> = - int (x * Suc n)" by (simp only: of_nat_mult [symmetric])
haftmann@33320
  1335
      finally have "- int (x * Suc n) = int y" ..
haftmann@33320
  1336
      then show ?thesis by (simp only: negative_eq_positive) auto
haftmann@33320
  1337
    qed
haftmann@33320
  1338
  qed
haftmann@33320
  1339
  then show ?thesis by (auto elim!: dvdE simp only: dvd_triv_left of_nat_mult)
haftmann@33320
  1340
qed
haftmann@33320
  1341
wenzelm@42676
  1342
lemma zdvd1_eq[simp]: "(x::int) dvd 1 = (\<bar>x\<bar> = 1)"
haftmann@33320
  1343
proof
haftmann@33320
  1344
  assume d: "x dvd 1" hence "int (nat \<bar>x\<bar>) dvd int (nat 1)" by simp
haftmann@33320
  1345
  hence "nat \<bar>x\<bar> dvd 1" by (simp add: zdvd_int)
haftmann@33320
  1346
  hence "nat \<bar>x\<bar> = 1"  by simp
wenzelm@42676
  1347
  thus "\<bar>x\<bar> = 1" by (cases "x < 0") auto
haftmann@33320
  1348
next
haftmann@33320
  1349
  assume "\<bar>x\<bar>=1"
haftmann@33320
  1350
  then have "x = 1 \<or> x = -1" by auto
haftmann@33320
  1351
  then show "x dvd 1" by (auto intro: dvdI)
haftmann@33320
  1352
qed
haftmann@33320
  1353
lp15@60162
  1354
lemma zdvd_mult_cancel1:
haftmann@33320
  1355
  assumes mp:"m \<noteq>(0::int)" shows "(m * n dvd m) = (\<bar>n\<bar> = 1)"
haftmann@33320
  1356
proof
lp15@60162
  1357
  assume n1: "\<bar>n\<bar> = 1" thus "m * n dvd m"
wenzelm@42676
  1358
    by (cases "n >0") (auto simp add: minus_equation_iff)
haftmann@33320
  1359
next
haftmann@33320
  1360
  assume H: "m * n dvd m" hence H2: "m * n dvd m * 1" by simp
haftmann@33320
  1361
  from zdvd_mult_cancel[OF H2 mp] show "\<bar>n\<bar> = 1" by (simp only: zdvd1_eq)
haftmann@33320
  1362
qed
haftmann@33320
  1363
haftmann@33320
  1364
lemma int_dvd_iff: "(int m dvd z) = (m dvd nat (abs z))"
haftmann@33320
  1365
  unfolding zdvd_int by (cases "z \<ge> 0") simp_all
haftmann@33320
  1366
haftmann@33320
  1367
lemma dvd_int_iff: "(z dvd int m) = (nat (abs z) dvd m)"
haftmann@33320
  1368
  unfolding zdvd_int by (cases "z \<ge> 0") simp_all
haftmann@33320
  1369
haftmann@58650
  1370
lemma dvd_int_unfold_dvd_nat:
haftmann@58650
  1371
  "k dvd l \<longleftrightarrow> nat \<bar>k\<bar> dvd nat \<bar>l\<bar>"
haftmann@58650
  1372
  unfolding dvd_int_iff [symmetric] by simp
haftmann@58650
  1373
haftmann@33320
  1374
lemma nat_dvd_iff: "(nat z dvd m) = (if 0 \<le> z then (z dvd int m) else m = 0)"
haftmann@33320
  1375
  by (auto simp add: dvd_int_iff)
haftmann@33320
  1376
haftmann@33341
  1377
lemma eq_nat_nat_iff:
haftmann@33341
  1378
  "0 \<le> z \<Longrightarrow> 0 \<le> z' \<Longrightarrow> nat z = nat z' \<longleftrightarrow> z = z'"
haftmann@33341
  1379
  by (auto elim!: nonneg_eq_int)
haftmann@33341
  1380
haftmann@33341
  1381
lemma nat_power_eq:
haftmann@33341
  1382
  "0 \<le> z \<Longrightarrow> nat (z ^ n) = nat z ^ n"
haftmann@33341
  1383
  by (induct n) (simp_all add: nat_mult_distrib)
haftmann@33341
  1384
haftmann@33320
  1385
lemma zdvd_imp_le: "[| z dvd n; 0 < n |] ==> z \<le> (n::int)"
wenzelm@42676
  1386
  apply (cases n)
haftmann@33320
  1387
  apply (auto simp add: dvd_int_iff)
wenzelm@42676
  1388
  apply (cases z)
haftmann@33320
  1389
  apply (auto simp add: dvd_imp_le)
haftmann@33320
  1390
  done
haftmann@33320
  1391
haftmann@36749
  1392
lemma zdvd_period:
haftmann@36749
  1393
  fixes a d :: int
haftmann@36749
  1394
  assumes "a dvd d"
haftmann@36749
  1395
  shows "a dvd (x + t) \<longleftrightarrow> a dvd ((x + c * d) + t)"
haftmann@36749
  1396
proof -
haftmann@36749
  1397
  from assms obtain k where "d = a * k" by (rule dvdE)
wenzelm@42676
  1398
  show ?thesis
wenzelm@42676
  1399
  proof
haftmann@36749
  1400
    assume "a dvd (x + t)"
haftmann@36749
  1401
    then obtain l where "x + t = a * l" by (rule dvdE)
haftmann@36749
  1402
    then have "x = a * l - t" by simp
wenzelm@60758
  1403
    with \<open>d = a * k\<close> show "a dvd x + c * d + t" by simp
haftmann@36749
  1404
  next
haftmann@36749
  1405
    assume "a dvd x + c * d + t"
haftmann@36749
  1406
    then obtain l where "x + c * d + t = a * l" by (rule dvdE)
haftmann@36749
  1407
    then have "x = a * l - c * d - t" by simp
wenzelm@60758
  1408
    with \<open>d = a * k\<close> show "a dvd (x + t)" by simp
haftmann@36749
  1409
  qed
haftmann@36749
  1410
qed
haftmann@36749
  1411
haftmann@33320
  1412
wenzelm@60758
  1413
subsection \<open>Finiteness of intervals\<close>
bulwahn@46756
  1414
bulwahn@46756
  1415
lemma finite_interval_int1 [iff]: "finite {i :: int. a <= i & i <= b}"
bulwahn@46756
  1416
proof (cases "a <= b")
bulwahn@46756
  1417
  case True
bulwahn@46756
  1418
  from this show ?thesis
bulwahn@46756
  1419
  proof (induct b rule: int_ge_induct)
bulwahn@46756
  1420
    case base
bulwahn@46756
  1421
    have "{i. a <= i & i <= a} = {a}" by auto
bulwahn@46756
  1422
    from this show ?case by simp
bulwahn@46756
  1423
  next
bulwahn@46756
  1424
    case (step b)
bulwahn@46756
  1425
    from this have "{i. a <= i & i <= b + 1} = {i. a <= i & i <= b} \<union> {b + 1}" by auto
bulwahn@46756
  1426
    from this step show ?case by simp
bulwahn@46756
  1427
  qed
bulwahn@46756
  1428
next
bulwahn@46756
  1429
  case False from this show ?thesis
bulwahn@46756
  1430
    by (metis (lifting, no_types) Collect_empty_eq finite.emptyI order_trans)
bulwahn@46756
  1431
qed
bulwahn@46756
  1432
bulwahn@46756
  1433
lemma finite_interval_int2 [iff]: "finite {i :: int. a <= i & i < b}"
bulwahn@46756
  1434
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1435
bulwahn@46756
  1436
lemma finite_interval_int3 [iff]: "finite {i :: int. a < i & i <= b}"
bulwahn@46756
  1437
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1438
bulwahn@46756
  1439
lemma finite_interval_int4 [iff]: "finite {i :: int. a < i & i < b}"
bulwahn@46756
  1440
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1441
bulwahn@46756
  1442
wenzelm@60758
  1443
subsection \<open>Configuration of the code generator\<close>
haftmann@25919
  1444
wenzelm@60758
  1445
text \<open>Constructors\<close>
huffman@47108
  1446
huffman@47108
  1447
definition Pos :: "num \<Rightarrow> int" where
huffman@47108
  1448
  [simp, code_abbrev]: "Pos = numeral"
huffman@47108
  1449
huffman@47108
  1450
definition Neg :: "num \<Rightarrow> int" where
haftmann@54489
  1451
  [simp, code_abbrev]: "Neg n = - (Pos n)"
huffman@47108
  1452
huffman@47108
  1453
code_datatype "0::int" Pos Neg
huffman@47108
  1454
huffman@47108
  1455
wenzelm@60758
  1456
text \<open>Auxiliary operations\<close>
huffman@47108
  1457
huffman@47108
  1458
definition dup :: "int \<Rightarrow> int" where
huffman@47108
  1459
  [simp]: "dup k = k + k"
haftmann@26507
  1460
huffman@47108
  1461
lemma dup_code [code]:
huffman@47108
  1462
  "dup 0 = 0"
huffman@47108
  1463
  "dup (Pos n) = Pos (Num.Bit0 n)"
huffman@47108
  1464
  "dup (Neg n) = Neg (Num.Bit0 n)"
haftmann@54489
  1465
  unfolding Pos_def Neg_def
huffman@47108
  1466
  by (simp_all add: numeral_Bit0)
huffman@47108
  1467
huffman@47108
  1468
definition sub :: "num \<Rightarrow> num \<Rightarrow> int" where
huffman@47108
  1469
  [simp]: "sub m n = numeral m - numeral n"
haftmann@26507
  1470
huffman@47108
  1471
lemma sub_code [code]:
huffman@47108
  1472
  "sub Num.One Num.One = 0"
huffman@47108
  1473
  "sub (Num.Bit0 m) Num.One = Pos (Num.BitM m)"
huffman@47108
  1474
  "sub (Num.Bit1 m) Num.One = Pos (Num.Bit0 m)"
huffman@47108
  1475
  "sub Num.One (Num.Bit0 n) = Neg (Num.BitM n)"
huffman@47108
  1476
  "sub Num.One (Num.Bit1 n) = Neg (Num.Bit0 n)"
huffman@47108
  1477
  "sub (Num.Bit0 m) (Num.Bit0 n) = dup (sub m n)"
huffman@47108
  1478
  "sub (Num.Bit1 m) (Num.Bit1 n) = dup (sub m n)"
huffman@47108
  1479
  "sub (Num.Bit1 m) (Num.Bit0 n) = dup (sub m n) + 1"
huffman@47108
  1480
  "sub (Num.Bit0 m) (Num.Bit1 n) = dup (sub m n) - 1"
haftmann@54489
  1481
  apply (simp_all only: sub_def dup_def numeral.simps Pos_def Neg_def numeral_BitM)
haftmann@54230
  1482
  apply (simp_all only: algebra_simps minus_diff_eq)
haftmann@54230
  1483
  apply (simp_all only: add.commute [of _ "- (numeral n + numeral n)"])
haftmann@54230
  1484
  apply (simp_all only: minus_add add.assoc left_minus)
haftmann@54230
  1485
  done
huffman@47108
  1486
wenzelm@60758
  1487
text \<open>Implementations\<close>
huffman@47108
  1488
huffman@47108
  1489
lemma one_int_code [code, code_unfold]:
huffman@47108
  1490
  "1 = Pos Num.One"
huffman@47108
  1491
  by simp
huffman@47108
  1492
huffman@47108
  1493
lemma plus_int_code [code]:
huffman@47108
  1494
  "k + 0 = (k::int)"
huffman@47108
  1495
  "0 + l = (l::int)"
huffman@47108
  1496
  "Pos m + Pos n = Pos (m + n)"
huffman@47108
  1497
  "Pos m + Neg n = sub m n"
huffman@47108
  1498
  "Neg m + Pos n = sub n m"
huffman@47108
  1499
  "Neg m + Neg n = Neg (m + n)"
huffman@47108
  1500
  by simp_all
haftmann@26507
  1501
huffman@47108
  1502
lemma uminus_int_code [code]:
huffman@47108
  1503
  "uminus 0 = (0::int)"
huffman@47108
  1504
  "uminus (Pos m) = Neg m"
huffman@47108
  1505
  "uminus (Neg m) = Pos m"
huffman@47108
  1506
  by simp_all
huffman@47108
  1507
huffman@47108
  1508
lemma minus_int_code [code]:
huffman@47108
  1509
  "k - 0 = (k::int)"
huffman@47108
  1510
  "0 - l = uminus (l::int)"
huffman@47108
  1511
  "Pos m - Pos n = sub m n"
huffman@47108
  1512
  "Pos m - Neg n = Pos (m + n)"
huffman@47108
  1513
  "Neg m - Pos n = Neg (m + n)"
huffman@47108
  1514
  "Neg m - Neg n = sub n m"
huffman@47108
  1515
  by simp_all
huffman@47108
  1516
huffman@47108
  1517
lemma times_int_code [code]:
huffman@47108
  1518
  "k * 0 = (0::int)"
huffman@47108
  1519
  "0 * l = (0::int)"
huffman@47108
  1520
  "Pos m * Pos n = Pos (m * n)"
huffman@47108
  1521
  "Pos m * Neg n = Neg (m * n)"
huffman@47108
  1522
  "Neg m * Pos n = Neg (m * n)"
huffman@47108
  1523
  "Neg m * Neg n = Pos (m * n)"
huffman@47108
  1524
  by simp_all
haftmann@26507
  1525
haftmann@38857
  1526
instantiation int :: equal
haftmann@26507
  1527
begin
haftmann@26507
  1528
haftmann@37767
  1529
definition
huffman@47108
  1530
  "HOL.equal k l \<longleftrightarrow> k = (l::int)"
haftmann@38857
  1531
huffman@47108
  1532
instance by default (rule equal_int_def)
haftmann@26507
  1533
haftmann@26507
  1534
end
haftmann@26507
  1535
huffman@47108
  1536
lemma equal_int_code [code]:
huffman@47108
  1537
  "HOL.equal 0 (0::int) \<longleftrightarrow> True"
huffman@47108
  1538
  "HOL.equal 0 (Pos l) \<longleftrightarrow> False"
huffman@47108
  1539
  "HOL.equal 0 (Neg l) \<longleftrightarrow> False"
huffman@47108
  1540
  "HOL.equal (Pos k) 0 \<longleftrightarrow> False"
huffman@47108
  1541
  "HOL.equal (Pos k) (Pos l) \<longleftrightarrow> HOL.equal k l"
huffman@47108
  1542
  "HOL.equal (Pos k) (Neg l) \<longleftrightarrow> False"
huffman@47108
  1543
  "HOL.equal (Neg k) 0 \<longleftrightarrow> False"
huffman@47108
  1544
  "HOL.equal (Neg k) (Pos l) \<longleftrightarrow> False"
huffman@47108
  1545
  "HOL.equal (Neg k) (Neg l) \<longleftrightarrow> HOL.equal k l"
huffman@47108
  1546
  by (auto simp add: equal)
haftmann@26507
  1547
huffman@47108
  1548
lemma equal_int_refl [code nbe]:
haftmann@38857
  1549
  "HOL.equal (k::int) k \<longleftrightarrow> True"
huffman@47108
  1550
  by (fact equal_refl)
haftmann@26507
  1551
haftmann@28562
  1552
lemma less_eq_int_code [code]:
huffman@47108
  1553
  "0 \<le> (0::int) \<longleftrightarrow> True"
huffman@47108
  1554
  "0 \<le> Pos l \<longleftrightarrow> True"
huffman@47108
  1555
  "0 \<le> Neg l \<longleftrightarrow> False"
huffman@47108
  1556
  "Pos k \<le> 0 \<longleftrightarrow> False"
huffman@47108
  1557
  "Pos k \<le> Pos l \<longleftrightarrow> k \<le> l"
huffman@47108
  1558
  "Pos k \<le> Neg l \<longleftrightarrow> False"
huffman@47108
  1559
  "Neg k \<le> 0 \<longleftrightarrow> True"
huffman@47108
  1560
  "Neg k \<le> Pos l \<longleftrightarrow> True"
huffman@47108
  1561
  "Neg k \<le> Neg l \<longleftrightarrow> l \<le> k"
huffman@28958
  1562
  by simp_all
haftmann@26507
  1563
haftmann@28562
  1564
lemma less_int_code [code]:
huffman@47108
  1565
  "0 < (0::int) \<longleftrightarrow> False"
huffman@47108
  1566
  "0 < Pos l \<longleftrightarrow> True"
huffman@47108
  1567
  "0 < Neg l \<longleftrightarrow> False"
huffman@47108
  1568
  "Pos k < 0 \<longleftrightarrow> False"
huffman@47108
  1569
  "Pos k < Pos l \<longleftrightarrow> k < l"
huffman@47108
  1570
  "Pos k < Neg l \<longleftrightarrow> False"
huffman@47108
  1571
  "Neg k < 0 \<longleftrightarrow> True"
huffman@47108
  1572
  "Neg k < Pos l \<longleftrightarrow> True"
huffman@47108
  1573
  "Neg k < Neg l \<longleftrightarrow> l < k"
huffman@28958
  1574
  by simp_all
haftmann@25919
  1575
huffman@47108
  1576
lemma nat_code [code]:
huffman@47108
  1577
  "nat (Int.Neg k) = 0"
huffman@47108
  1578
  "nat 0 = 0"
huffman@47108
  1579
  "nat (Int.Pos k) = nat_of_num k"
haftmann@54489
  1580
  by (simp_all add: nat_of_num_numeral)
haftmann@25928
  1581
huffman@47108
  1582
lemma (in ring_1) of_int_code [code]:
haftmann@54489
  1583
  "of_int (Int.Neg k) = - numeral k"
huffman@47108
  1584
  "of_int 0 = 0"
huffman@47108
  1585
  "of_int (Int.Pos k) = numeral k"
huffman@47108
  1586
  by simp_all
haftmann@25919
  1587
huffman@47108
  1588
wenzelm@60758
  1589
text \<open>Serializer setup\<close>
haftmann@25919
  1590
haftmann@52435
  1591
code_identifier
haftmann@52435
  1592
  code_module Int \<rightharpoonup> (SML) Arith and (OCaml) Arith and (Haskell) Arith
haftmann@25919
  1593
haftmann@25919
  1594
quickcheck_params [default_type = int]
haftmann@25919
  1595
huffman@47108
  1596
hide_const (open) Pos Neg sub dup
haftmann@25919
  1597
haftmann@25919
  1598
wenzelm@60758
  1599
subsection \<open>Legacy theorems\<close>
haftmann@25919
  1600
haftmann@25919
  1601
lemmas inj_int = inj_of_nat [where 'a=int]
haftmann@25919
  1602
lemmas zadd_int = of_nat_add [where 'a=int, symmetric]
haftmann@25919
  1603
lemmas int_mult = of_nat_mult [where 'a=int]
haftmann@25919
  1604
lemmas zmult_int = of_nat_mult [where 'a=int, symmetric]
wenzelm@45607
  1605
lemmas int_eq_0_conv = of_nat_eq_0_iff [where 'a=int and m="n"] for n
haftmann@25919
  1606
lemmas zless_int = of_nat_less_iff [where 'a=int]
wenzelm@45607
  1607
lemmas int_less_0_conv = of_nat_less_0_iff [where 'a=int and m="k"] for k
haftmann@25919
  1608
lemmas zero_less_int_conv = of_nat_0_less_iff [where 'a=int]
haftmann@25919
  1609
lemmas zero_zle_int = of_nat_0_le_iff [where 'a=int]
wenzelm@45607
  1610
lemmas int_le_0_conv = of_nat_le_0_iff [where 'a=int and m="n"] for n
haftmann@25919
  1611
lemmas int_0 = of_nat_0 [where 'a=int]
haftmann@25919
  1612
lemmas int_1 = of_nat_1 [where 'a=int]
haftmann@25919
  1613
lemmas int_Suc = of_nat_Suc [where 'a=int]
huffman@47207
  1614
lemmas int_numeral = of_nat_numeral [where 'a=int]
wenzelm@45607
  1615
lemmas abs_int_eq = abs_of_nat [where 'a=int and n="m"] for m
haftmann@25919
  1616
lemmas of_int_int_eq = of_int_of_nat_eq [where 'a=int]
haftmann@25919
  1617
lemmas zdiff_int = of_nat_diff [where 'a=int, symmetric]
huffman@47255
  1618
lemmas zpower_numeral_even = power_numeral_even [where 'a=int]
huffman@47255
  1619
lemmas zpower_numeral_odd = power_numeral_odd [where 'a=int]
haftmann@30960
  1620
haftmann@31015
  1621
lemma zpower_zpower:
haftmann@31015
  1622
  "(x ^ y) ^ z = (x ^ (y * z)::int)"
haftmann@31015
  1623
  by (rule power_mult [symmetric])
haftmann@31015
  1624
haftmann@31015
  1625
lemma int_power:
haftmann@31015
  1626
  "int (m ^ n) = int m ^ n"
haftmann@54489
  1627
  by (fact of_nat_power)
haftmann@31015
  1628
haftmann@31015
  1629
lemmas zpower_int = int_power [symmetric]
haftmann@31015
  1630
wenzelm@60758
  1631
text \<open>De-register @{text "int"} as a quotient type:\<close>
huffman@48045
  1632
kuncar@53652
  1633
lifting_update int.lifting
kuncar@53652
  1634
lifting_forget int.lifting
huffman@48045
  1635
wenzelm@60758
  1636
text\<open>Also the class for fields with characteristic zero.\<close>
lp15@59667
  1637
class field_char_0 = field + ring_char_0
lp15@59667
  1638
subclass (in linordered_field) field_char_0 ..
lp15@59667
  1639
haftmann@25919
  1640
end