src/HOL/Int.thy
author eberlm
Mon Jan 11 16:38:39 2016 +0100 (2016-01-11)
changeset 62128 3201ddb00097
parent 61944 5d06ecfdb472
child 62347 2230b7047376
permissions -rw-r--r--
Integrated some material from Algebraic_Numbers AFP entry to Polynomials; generalised some polynomial stuff.
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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 standard (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 standard (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 :: int \<Rightarrow> int \<Rightarrow> int) = min"
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definition
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  "(sup :: 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::int\<bar> = (if i < 0 then - i else i)"
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definition
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  zsgn_def: "sgn (i::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::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::int) \<le> z"
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  by transfer clarsimp
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lemma zless_iff_Suc_zadd:
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  "(w :: 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 \<open>ring_1\<close>: \<open>of_int\<close>\<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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lemma mult_of_int_commute: "of_int x * y = y * of_int x"
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  by (transfer fixing: times) (auto simp: algebra_simps mult_of_nat_commute)
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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 [simp]:
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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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lemma of_int_eq_1_iff [iff]:
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   "of_int z = 1 \<longleftrightarrow> z = 1"
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  using of_int_eq_iff [of z 1] 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 \<open>linordered_idom\<close> 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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lemma of_int_1_le_iff [simp]:
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  "1 \<le> of_int z \<longleftrightarrow> 1 \<le> z"
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  using of_int_le_iff [of 1 z] by simp
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lemma of_int_le_1_iff [simp]:
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  "of_int z \<le> 1 \<longleftrightarrow> z \<le> 1"
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  using of_int_le_iff [of z 1] by simp
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lemma of_int_1_less_iff [simp]:
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  "1 < of_int z \<longleftrightarrow> 1 < z"
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  using of_int_less_iff [of 1 z] by simp
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lemma of_int_less_1_iff [simp]:
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  "of_int z < 1 \<longleftrightarrow> z < 1"
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  using of_int_less_iff [of z 1] by simp
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lemma of_int_pos: "z > 0 \<Longrightarrow> of_int z > 0"
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  by simp
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lemma of_int_nonneg: "z \<ge> 0 \<Longrightarrow> of_int z \<ge> 0"
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  by simp
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end
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text \<open>Comparisons involving @{term of_int}.\<close>
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lemma of_int_eq_numeral_iff [iff]:
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   "of_int z = (numeral n :: 'a::ring_char_0)
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   \<longleftrightarrow> z = numeral n"
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  using of_int_eq_iff by fastforce
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lemma of_int_le_numeral_iff [simp]:
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   "of_int z \<le> (numeral n :: 'a::linordered_idom)
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   \<longleftrightarrow> z \<le> numeral n"
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  using of_int_le_iff [of z "numeral n"] by simp
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lemma of_int_numeral_le_iff [simp]:
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   "(numeral n :: 'a::linordered_idom) \<le> of_int z \<longleftrightarrow> numeral n \<le> z"
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   339
  using of_int_le_iff [of "numeral n"] by simp
lp15@61234
   340
lp15@61649
   341
lemma of_int_less_numeral_iff [simp]:
lp15@61649
   342
   "of_int z < (numeral n :: 'a::linordered_idom)
lp15@61234
   343
   \<longleftrightarrow> z < numeral n"
lp15@61234
   344
  using of_int_less_iff [of z "numeral n"] by simp
lp15@61234
   345
lp15@61649
   346
lemma of_int_numeral_less_iff [simp]:
lp15@61234
   347
   "(numeral n :: 'a::linordered_idom) < of_int z \<longleftrightarrow> numeral n < z"
lp15@61234
   348
  using of_int_less_iff [of "numeral n" z] by simp
lp15@61234
   349
hoelzl@56889
   350
lemma of_nat_less_of_int_iff:
hoelzl@56889
   351
  "(of_nat n::'a::linordered_idom) < of_int x \<longleftrightarrow> int n < x"
hoelzl@56889
   352
  by (metis of_int_of_nat_eq of_int_less_iff)
hoelzl@56889
   353
haftmann@25919
   354
lemma of_int_eq_id [simp]: "of_int = id"
haftmann@25919
   355
proof
haftmann@25919
   356
  fix z show "of_int z = id z"
huffman@48045
   357
    by (cases z rule: int_diff_cases, simp)
haftmann@25919
   358
qed
haftmann@25919
   359
haftmann@25919
   360
hoelzl@51329
   361
instance int :: no_top
wenzelm@61169
   362
  apply standard
hoelzl@51329
   363
  apply (rule_tac x="x + 1" in exI)
hoelzl@51329
   364
  apply simp
hoelzl@51329
   365
  done
hoelzl@51329
   366
hoelzl@51329
   367
instance int :: no_bot
wenzelm@61169
   368
  apply standard
hoelzl@51329
   369
  apply (rule_tac x="x - 1" in exI)
hoelzl@51329
   370
  apply simp
hoelzl@51329
   371
  done
hoelzl@51329
   372
wenzelm@61799
   373
subsection \<open>Magnitude of an Integer, as a Natural Number: \<open>nat\<close>\<close>
haftmann@25919
   374
huffman@48045
   375
lift_definition nat :: "int \<Rightarrow> nat" is "\<lambda>(x, y). x - y"
huffman@48045
   376
  by auto
haftmann@25919
   377
huffman@44709
   378
lemma nat_int [simp]: "nat (int n) = n"
huffman@48045
   379
  by transfer simp
haftmann@25919
   380
huffman@44709
   381
lemma int_nat_eq [simp]: "int (nat z) = (if 0 \<le> z then z else 0)"
huffman@48045
   382
  by transfer clarsimp
haftmann@25919
   383
huffman@44709
   384
corollary nat_0_le: "0 \<le> z ==> int (nat z) = z"
haftmann@25919
   385
by simp
haftmann@25919
   386
haftmann@25919
   387
lemma nat_le_0 [simp]: "z \<le> 0 ==> nat z = 0"
huffman@48045
   388
  by transfer clarsimp
haftmann@25919
   389
haftmann@25919
   390
lemma nat_le_eq_zle: "0 < w | 0 \<le> z ==> (nat w \<le> nat z) = (w\<le>z)"
huffman@48045
   391
  by transfer (clarsimp, arith)
haftmann@25919
   392
wenzelm@60758
   393
text\<open>An alternative condition is @{term "0 \<le> w"}\<close>
haftmann@25919
   394
corollary nat_mono_iff: "0 < z ==> (nat w < nat z) = (w < z)"
lp15@60162
   395
by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
haftmann@25919
   396
haftmann@25919
   397
corollary nat_less_eq_zless: "0 \<le> w ==> (nat w < nat z) = (w<z)"
lp15@60162
   398
by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
haftmann@25919
   399
haftmann@25919
   400
lemma zless_nat_conj [simp]: "(nat w < nat z) = (0 < z & w < z)"
huffman@48045
   401
  by transfer (clarsimp, arith)
haftmann@25919
   402
haftmann@25919
   403
lemma nonneg_eq_int:
haftmann@25919
   404
  fixes z :: int
huffman@44709
   405
  assumes "0 \<le> z" and "\<And>m. z = int m \<Longrightarrow> P"
haftmann@25919
   406
  shows P
haftmann@25919
   407
  using assms by (blast dest: nat_0_le sym)
haftmann@25919
   408
haftmann@54223
   409
lemma nat_eq_iff:
haftmann@54223
   410
  "nat w = m \<longleftrightarrow> (if 0 \<le> w then w = int m else m = 0)"
huffman@48045
   411
  by transfer (clarsimp simp add: le_imp_diff_is_add)
lp15@60162
   412
haftmann@54223
   413
corollary nat_eq_iff2:
haftmann@54223
   414
  "m = nat w \<longleftrightarrow> (if 0 \<le> w then w = int m else m = 0)"
haftmann@54223
   415
  using nat_eq_iff [of w m] by auto
haftmann@54223
   416
haftmann@54223
   417
lemma nat_0 [simp]:
haftmann@54223
   418
  "nat 0 = 0"
haftmann@54223
   419
  by (simp add: nat_eq_iff)
haftmann@25919
   420
haftmann@54223
   421
lemma nat_1 [simp]:
haftmann@54223
   422
  "nat 1 = Suc 0"
haftmann@54223
   423
  by (simp add: nat_eq_iff)
haftmann@54223
   424
haftmann@54223
   425
lemma nat_numeral [simp]:
haftmann@54223
   426
  "nat (numeral k) = numeral k"
haftmann@54223
   427
  by (simp add: nat_eq_iff)
haftmann@25919
   428
haftmann@54223
   429
lemma nat_neg_numeral [simp]:
haftmann@54489
   430
  "nat (- numeral k) = 0"
haftmann@54223
   431
  by simp
haftmann@54223
   432
haftmann@54223
   433
lemma nat_2: "nat 2 = Suc (Suc 0)"
haftmann@54223
   434
  by simp
lp15@60162
   435
haftmann@25919
   436
lemma nat_less_iff: "0 \<le> w ==> (nat w < m) = (w < of_nat m)"
huffman@48045
   437
  by transfer (clarsimp, arith)
haftmann@25919
   438
huffman@44709
   439
lemma nat_le_iff: "nat x \<le> n \<longleftrightarrow> x \<le> int n"
huffman@48045
   440
  by transfer (clarsimp simp add: le_diff_conv)
huffman@44707
   441
huffman@44707
   442
lemma nat_mono: "x \<le> y \<Longrightarrow> nat x \<le> nat y"
huffman@48045
   443
  by transfer auto
huffman@44707
   444
nipkow@29700
   445
lemma nat_0_iff[simp]: "nat(i::int) = 0 \<longleftrightarrow> i\<le>0"
huffman@48045
   446
  by transfer clarsimp
nipkow@29700
   447
haftmann@25919
   448
lemma int_eq_iff: "(of_nat m = z) = (m = nat z & 0 \<le> z)"
haftmann@25919
   449
by (auto simp add: nat_eq_iff2)
haftmann@25919
   450
haftmann@25919
   451
lemma zero_less_nat_eq [simp]: "(0 < nat z) = (0 < z)"
haftmann@25919
   452
by (insert zless_nat_conj [of 0], auto)
haftmann@25919
   453
haftmann@25919
   454
lemma nat_add_distrib:
haftmann@54223
   455
  "0 \<le> z \<Longrightarrow> 0 \<le> z' \<Longrightarrow> nat (z + z') = nat z + nat z'"
huffman@48045
   456
  by transfer clarsimp
haftmann@25919
   457
haftmann@54223
   458
lemma nat_diff_distrib':
haftmann@54223
   459
  "0 \<le> x \<Longrightarrow> 0 \<le> y \<Longrightarrow> nat (x - y) = nat x - nat y"
haftmann@54223
   460
  by transfer clarsimp
lp15@60162
   461
haftmann@25919
   462
lemma nat_diff_distrib:
haftmann@54223
   463
  "0 \<le> z' \<Longrightarrow> z' \<le> z \<Longrightarrow> nat (z - z') = nat z - nat z'"
haftmann@54223
   464
  by (rule nat_diff_distrib') auto
haftmann@25919
   465
huffman@44709
   466
lemma nat_zminus_int [simp]: "nat (- int n) = 0"
huffman@48045
   467
  by transfer simp
haftmann@25919
   468
haftmann@53065
   469
lemma le_nat_iff:
haftmann@53065
   470
  "k \<ge> 0 \<Longrightarrow> n \<le> nat k \<longleftrightarrow> int n \<le> k"
haftmann@53065
   471
  by transfer auto
lp15@60162
   472
huffman@44709
   473
lemma zless_nat_eq_int_zless: "(m < nat z) = (int m < z)"
huffman@48045
   474
  by transfer (clarsimp simp add: less_diff_conv)
haftmann@25919
   475
haftmann@25919
   476
context ring_1
haftmann@25919
   477
begin
haftmann@25919
   478
lp15@61609
   479
lemma of_nat_nat [simp]: "0 \<le> z \<Longrightarrow> of_nat (nat z) = of_int z"
huffman@48066
   480
  by transfer (clarsimp simp add: of_nat_diff)
haftmann@25919
   481
haftmann@25919
   482
end
haftmann@25919
   483
lp15@60162
   484
lemma diff_nat_numeral [simp]:
haftmann@54249
   485
  "(numeral v :: nat) - numeral v' = nat (numeral v - numeral v')"
haftmann@54249
   486
  by (simp only: nat_diff_distrib' zero_le_numeral nat_numeral)
haftmann@54249
   487
haftmann@54249
   488
wenzelm@60758
   489
text \<open>For termination proofs:\<close>
krauss@29779
   490
lemma measure_function_int[measure_function]: "is_measure (nat o abs)" ..
krauss@29779
   491
haftmann@25919
   492
wenzelm@60758
   493
subsection\<open>Lemmas about the Function @{term of_nat} and Orderings\<close>
haftmann@25919
   494
wenzelm@61076
   495
lemma negative_zless_0: "- (int (Suc n)) < (0 :: int)"
haftmann@25919
   496
by (simp add: order_less_le del: of_nat_Suc)
haftmann@25919
   497
huffman@44709
   498
lemma negative_zless [iff]: "- (int (Suc n)) < int m"
haftmann@25919
   499
by (rule negative_zless_0 [THEN order_less_le_trans], simp)
haftmann@25919
   500
huffman@44709
   501
lemma negative_zle_0: "- int n \<le> 0"
haftmann@25919
   502
by (simp add: minus_le_iff)
haftmann@25919
   503
huffman@44709
   504
lemma negative_zle [iff]: "- int n \<le> int m"
haftmann@25919
   505
by (rule order_trans [OF negative_zle_0 of_nat_0_le_iff])
haftmann@25919
   506
huffman@44709
   507
lemma not_zle_0_negative [simp]: "~ (0 \<le> - (int (Suc n)))"
haftmann@25919
   508
by (subst le_minus_iff, simp del: of_nat_Suc)
haftmann@25919
   509
huffman@44709
   510
lemma int_zle_neg: "(int n \<le> - int m) = (n = 0 & m = 0)"
huffman@48045
   511
  by transfer simp
haftmann@25919
   512
huffman@44709
   513
lemma not_int_zless_negative [simp]: "~ (int n < - int m)"
haftmann@25919
   514
by (simp add: linorder_not_less)
haftmann@25919
   515
huffman@44709
   516
lemma negative_eq_positive [simp]: "(- int n = of_nat m) = (n = 0 & m = 0)"
haftmann@25919
   517
by (force simp add: order_eq_iff [of "- of_nat n"] int_zle_neg)
haftmann@25919
   518
huffman@44709
   519
lemma zle_iff_zadd: "w \<le> z \<longleftrightarrow> (\<exists>n. z = w + int n)"
haftmann@25919
   520
proof -
haftmann@25919
   521
  have "(w \<le> z) = (0 \<le> z - w)"
haftmann@25919
   522
    by (simp only: le_diff_eq add_0_left)
haftmann@25919
   523
  also have "\<dots> = (\<exists>n. z - w = of_nat n)"
haftmann@25919
   524
    by (auto elim: zero_le_imp_eq_int)
haftmann@25919
   525
  also have "\<dots> = (\<exists>n. z = w + of_nat n)"
nipkow@29667
   526
    by (simp only: algebra_simps)
haftmann@25919
   527
  finally show ?thesis .
haftmann@25919
   528
qed
haftmann@25919
   529
huffman@44709
   530
lemma zadd_int_left: "int m + (int n + z) = int (m + n) + z"
haftmann@25919
   531
by simp
haftmann@25919
   532
wenzelm@60758
   533
text\<open>This version is proved for all ordered rings, not just integers!
wenzelm@61799
   534
      It is proved here because attribute \<open>arith_split\<close> is not available
wenzelm@61799
   535
      in theory \<open>Rings\<close>.
wenzelm@61799
   536
      But is it really better than just rewriting with \<open>abs_if\<close>?\<close>
blanchet@54147
   537
lemma abs_split [arith_split, no_atp]:
wenzelm@61944
   538
     "P \<bar>a::'a::linordered_idom\<bar> = ((0 \<le> a --> P a) & (a < 0 --> P(-a)))"
haftmann@25919
   539
by (force dest: order_less_le_trans simp add: abs_if linorder_not_less)
haftmann@25919
   540
huffman@44709
   541
lemma negD: "x < 0 \<Longrightarrow> \<exists>n. x = - (int (Suc n))"
huffman@48045
   542
apply transfer
huffman@48045
   543
apply clarsimp
huffman@48045
   544
apply (rule_tac x="b - Suc a" in exI, arith)
haftmann@25919
   545
done
haftmann@25919
   546
wenzelm@60758
   547
subsection \<open>Cases and induction\<close>
haftmann@25919
   548
wenzelm@60758
   549
text\<open>Now we replace the case analysis rule by a more conventional one:
wenzelm@60758
   550
whether an integer is negative or not.\<close>
haftmann@25919
   551
wenzelm@60758
   552
text\<open>This version is symmetric in the two subgoals.\<close>
lp15@59613
   553
theorem int_cases2 [case_names nonneg nonpos, cases type: int]:
lp15@59613
   554
  "\<lbrakk>!! n. z = int n \<Longrightarrow> P;  !! n. z = - (int n) \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
lp15@59613
   555
apply (cases "z < 0")
lp15@59613
   556
apply (auto simp add: linorder_not_less dest!: negD nat_0_le [THEN sym])
lp15@59613
   557
done
lp15@59613
   558
wenzelm@60758
   559
text\<open>This is the default, with a negative case.\<close>
wenzelm@42676
   560
theorem int_cases [case_names nonneg neg, cases type: int]:
lp15@59613
   561
  "[|!! n. z = int n ==> P;  !! n. z = - (int (Suc n)) ==> P |] ==> P"
wenzelm@42676
   562
apply (cases "z < 0")
wenzelm@42676
   563
apply (blast dest!: negD)
haftmann@25919
   564
apply (simp add: linorder_not_less del: of_nat_Suc)
haftmann@25919
   565
apply auto
haftmann@25919
   566
apply (blast dest: nat_0_le [THEN sym])
haftmann@25919
   567
done
haftmann@25919
   568
haftmann@60868
   569
lemma int_cases3 [case_names zero pos neg]:
haftmann@60868
   570
  fixes k :: int
haftmann@60868
   571
  assumes "k = 0 \<Longrightarrow> P" and "\<And>n. k = int n \<Longrightarrow> n > 0 \<Longrightarrow> P"
paulson@61204
   572
    and "\<And>n. k = - int n \<Longrightarrow> n > 0 \<Longrightarrow> P"
haftmann@60868
   573
  shows "P"
haftmann@60868
   574
proof (cases k "0::int" rule: linorder_cases)
haftmann@60868
   575
  case equal with assms(1) show P by simp
haftmann@60868
   576
next
haftmann@60868
   577
  case greater
haftmann@60868
   578
  then have "nat k > 0" by simp
haftmann@60868
   579
  moreover from this have "k = int (nat k)" by auto
haftmann@60868
   580
  ultimately show P using assms(2) by blast
haftmann@60868
   581
next
haftmann@60868
   582
  case less
haftmann@60868
   583
  then have "nat (- k) > 0" by simp
haftmann@60868
   584
  moreover from this have "k = - int (nat (- k))" by auto
haftmann@60868
   585
  ultimately show P using assms(3) by blast
haftmann@60868
   586
qed
haftmann@60868
   587
wenzelm@42676
   588
theorem int_of_nat_induct [case_names nonneg neg, induct type: int]:
huffman@44709
   589
     "[|!! n. P (int n);  !!n. P (- (int (Suc n))) |] ==> P z"
wenzelm@42676
   590
  by (cases z) auto
haftmann@25919
   591
huffman@47207
   592
lemma nonneg_int_cases:
huffman@47207
   593
  assumes "0 \<le> k" obtains n where "k = int n"
haftmann@54489
   594
  using assms by (rule nonneg_eq_int)
huffman@47207
   595
huffman@47108
   596
lemma Let_numeral [simp]: "Let (numeral v) f = f (numeral v)"
wenzelm@61799
   597
  \<comment> \<open>Unfold all \<open>let\<close>s involving constants\<close>
wenzelm@61799
   598
  by (fact Let_numeral) \<comment> \<open>FIXME drop\<close>
haftmann@37767
   599
haftmann@54489
   600
lemma Let_neg_numeral [simp]: "Let (- numeral v) f = f (- numeral v)"
wenzelm@61799
   601
  \<comment> \<open>Unfold all \<open>let\<close>s involving constants\<close>
wenzelm@61799
   602
  by (fact Let_neg_numeral) \<comment> \<open>FIXME drop\<close>
haftmann@25919
   603
wenzelm@61799
   604
text \<open>Unfold \<open>min\<close> and \<open>max\<close> on numerals.\<close>
huffman@28958
   605
huffman@47108
   606
lemmas max_number_of [simp] =
huffman@47108
   607
  max_def [of "numeral u" "numeral v"]
haftmann@54489
   608
  max_def [of "numeral u" "- numeral v"]
haftmann@54489
   609
  max_def [of "- numeral u" "numeral v"]
haftmann@54489
   610
  max_def [of "- numeral u" "- numeral v"] for u v
huffman@28958
   611
huffman@47108
   612
lemmas min_number_of [simp] =
huffman@47108
   613
  min_def [of "numeral u" "numeral v"]
haftmann@54489
   614
  min_def [of "numeral u" "- numeral v"]
haftmann@54489
   615
  min_def [of "- numeral u" "numeral v"]
haftmann@54489
   616
  min_def [of "- numeral u" "- numeral v"] for u v
huffman@26075
   617
haftmann@25919
   618
wenzelm@60758
   619
subsubsection \<open>Binary comparisons\<close>
huffman@28958
   620
wenzelm@60758
   621
text \<open>Preliminaries\<close>
huffman@28958
   622
lp15@60162
   623
lemma le_imp_0_less:
huffman@28958
   624
  assumes le: "0 \<le> z"
huffman@28958
   625
  shows "(0::int) < 1 + z"
huffman@28958
   626
proof -
huffman@28958
   627
  have "0 \<le> z" by fact
huffman@47108
   628
  also have "... < z + 1" by (rule less_add_one)
haftmann@57514
   629
  also have "... = 1 + z" by (simp add: ac_simps)
huffman@28958
   630
  finally show "0 < 1 + z" .
huffman@28958
   631
qed
huffman@28958
   632
huffman@28958
   633
lemma odd_less_0_iff:
huffman@28958
   634
  "(1 + z + z < 0) = (z < (0::int))"
wenzelm@42676
   635
proof (cases z)
huffman@28958
   636
  case (nonneg n)
haftmann@57512
   637
  thus ?thesis by (simp add: linorder_not_less add.assoc add_increasing
lp15@60162
   638
                             le_imp_0_less [THEN order_less_imp_le])
huffman@28958
   639
next
huffman@28958
   640
  case (neg n)
huffman@30079
   641
  thus ?thesis by (simp del: of_nat_Suc of_nat_add of_nat_1
huffman@30079
   642
    add: algebra_simps of_nat_1 [where 'a=int, symmetric] of_nat_add [symmetric])
huffman@28958
   643
qed
huffman@28958
   644
wenzelm@60758
   645
subsubsection \<open>Comparisons, for Ordered Rings\<close>
haftmann@25919
   646
haftmann@25919
   647
lemmas double_eq_0_iff = double_zero
haftmann@25919
   648
haftmann@25919
   649
lemma odd_nonzero:
haftmann@33296
   650
  "1 + z + z \<noteq> (0::int)"
wenzelm@42676
   651
proof (cases z)
haftmann@25919
   652
  case (nonneg n)
lp15@60162
   653
  have le: "0 \<le> z+z" by (simp add: nonneg add_increasing)
haftmann@25919
   654
  thus ?thesis using  le_imp_0_less [OF le]
lp15@60162
   655
    by (auto simp add: add.assoc)
haftmann@25919
   656
next
haftmann@25919
   657
  case (neg n)
haftmann@25919
   658
  show ?thesis
haftmann@25919
   659
  proof
haftmann@25919
   660
    assume eq: "1 + z + z = 0"
huffman@44709
   661
    have "(0::int) < 1 + (int n + int n)"
lp15@60162
   662
      by (simp add: le_imp_0_less add_increasing)
lp15@60162
   663
    also have "... = - (1 + z + z)"
lp15@60162
   664
      by (simp add: neg add.assoc [symmetric])
lp15@60162
   665
    also have "... = 0" by (simp add: eq)
haftmann@25919
   666
    finally have "0<0" ..
haftmann@25919
   667
    thus False by blast
haftmann@25919
   668
  qed
haftmann@25919
   669
qed
haftmann@25919
   670
haftmann@30652
   671
wenzelm@60758
   672
subsection \<open>The Set of Integers\<close>
haftmann@25919
   673
haftmann@25919
   674
context ring_1
haftmann@25919
   675
begin
haftmann@25919
   676
wenzelm@61070
   677
definition Ints :: "'a set"  ("\<int>")
wenzelm@61070
   678
  where "\<int> = range of_int"
haftmann@25919
   679
huffman@35634
   680
lemma Ints_of_int [simp]: "of_int z \<in> \<int>"
huffman@35634
   681
  by (simp add: Ints_def)
huffman@35634
   682
huffman@35634
   683
lemma Ints_of_nat [simp]: "of_nat n \<in> \<int>"
huffman@45533
   684
  using Ints_of_int [of "of_nat n"] by simp
huffman@35634
   685
haftmann@25919
   686
lemma Ints_0 [simp]: "0 \<in> \<int>"
huffman@45533
   687
  using Ints_of_int [of "0"] by simp
haftmann@25919
   688
haftmann@25919
   689
lemma Ints_1 [simp]: "1 \<in> \<int>"
huffman@45533
   690
  using Ints_of_int [of "1"] by simp
haftmann@25919
   691
eberlm@61552
   692
lemma Ints_numeral [simp]: "numeral n \<in> \<int>"
eberlm@61552
   693
  by (subst of_nat_numeral [symmetric], rule Ints_of_nat)
eberlm@61552
   694
haftmann@25919
   695
lemma Ints_add [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a + b \<in> \<int>"
haftmann@25919
   696
apply (auto simp add: Ints_def)
haftmann@25919
   697
apply (rule range_eqI)
haftmann@25919
   698
apply (rule of_int_add [symmetric])
haftmann@25919
   699
done
haftmann@25919
   700
haftmann@25919
   701
lemma Ints_minus [simp]: "a \<in> \<int> \<Longrightarrow> -a \<in> \<int>"
haftmann@25919
   702
apply (auto simp add: Ints_def)
haftmann@25919
   703
apply (rule range_eqI)
haftmann@25919
   704
apply (rule of_int_minus [symmetric])
haftmann@25919
   705
done
haftmann@25919
   706
huffman@35634
   707
lemma Ints_diff [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a - b \<in> \<int>"
huffman@35634
   708
apply (auto simp add: Ints_def)
huffman@35634
   709
apply (rule range_eqI)
huffman@35634
   710
apply (rule of_int_diff [symmetric])
huffman@35634
   711
done
huffman@35634
   712
haftmann@25919
   713
lemma Ints_mult [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a * b \<in> \<int>"
haftmann@25919
   714
apply (auto simp add: Ints_def)
haftmann@25919
   715
apply (rule range_eqI)
haftmann@25919
   716
apply (rule of_int_mult [symmetric])
haftmann@25919
   717
done
haftmann@25919
   718
huffman@35634
   719
lemma Ints_power [simp]: "a \<in> \<int> \<Longrightarrow> a ^ n \<in> \<int>"
huffman@35634
   720
by (induct n) simp_all
huffman@35634
   721
haftmann@25919
   722
lemma Ints_cases [cases set: Ints]:
haftmann@25919
   723
  assumes "q \<in> \<int>"
haftmann@25919
   724
  obtains (of_int) z where "q = of_int z"
haftmann@25919
   725
  unfolding Ints_def
haftmann@25919
   726
proof -
wenzelm@60758
   727
  from \<open>q \<in> \<int>\<close> have "q \<in> range of_int" unfolding Ints_def .
haftmann@25919
   728
  then obtain z where "q = of_int z" ..
haftmann@25919
   729
  then show thesis ..
haftmann@25919
   730
qed
haftmann@25919
   731
haftmann@25919
   732
lemma Ints_induct [case_names of_int, induct set: Ints]:
haftmann@25919
   733
  "q \<in> \<int> \<Longrightarrow> (\<And>z. P (of_int z)) \<Longrightarrow> P q"
haftmann@25919
   734
  by (rule Ints_cases) auto
haftmann@25919
   735
eberlm@61524
   736
lemma Nats_subset_Ints: "\<nat> \<subseteq> \<int>"
eberlm@61524
   737
  unfolding Nats_def Ints_def
eberlm@61524
   738
  by (rule subsetI, elim imageE, hypsubst, subst of_int_of_nat_eq[symmetric], rule imageI) simp_all
eberlm@61524
   739
eberlm@61524
   740
lemma Nats_altdef1: "\<nat> = {of_int n |n. n \<ge> 0}"
eberlm@61524
   741
proof (intro subsetI equalityI)
eberlm@61524
   742
  fix x :: 'a assume "x \<in> {of_int n |n. n \<ge> 0}"
eberlm@61524
   743
  then obtain n where "x = of_int n" "n \<ge> 0" by (auto elim!: Ints_cases)
eberlm@61524
   744
  hence "x = of_nat (nat n)" by (subst of_nat_nat) simp_all
eberlm@61524
   745
  thus "x \<in> \<nat>" by simp
eberlm@61524
   746
next
eberlm@61524
   747
  fix x :: 'a assume "x \<in> \<nat>"
eberlm@61524
   748
  then obtain n where "x = of_nat n" by (auto elim!: Nats_cases)
eberlm@61524
   749
  hence "x = of_int (int n)" by simp
eberlm@61524
   750
  also have "int n \<ge> 0" by simp
eberlm@61524
   751
  hence "of_int (int n) \<in> {of_int n |n. n \<ge> 0}" by blast
eberlm@61524
   752
  finally show "x \<in> {of_int n |n. n \<ge> 0}" .
eberlm@61524
   753
qed
eberlm@61524
   754
haftmann@25919
   755
end
haftmann@25919
   756
eberlm@61524
   757
lemma (in linordered_idom) Nats_altdef2: "\<nat> = {n \<in> \<int>. n \<ge> 0}"
eberlm@61524
   758
proof (intro subsetI equalityI)
eberlm@61524
   759
  fix x :: 'a assume "x \<in> {n \<in> \<int>. n \<ge> 0}"
eberlm@61524
   760
  then obtain n where "x = of_int n" "n \<ge> 0" by (auto elim!: Ints_cases)
eberlm@61524
   761
  hence "x = of_nat (nat n)" by (subst of_nat_nat) simp_all
eberlm@61524
   762
  thus "x \<in> \<nat>" by simp
eberlm@61524
   763
qed (auto elim!: Nats_cases)
eberlm@61524
   764
eberlm@61524
   765
wenzelm@60758
   766
text \<open>The premise involving @{term Ints} prevents @{term "a = 1/2"}.\<close>
haftmann@25919
   767
haftmann@25919
   768
lemma Ints_double_eq_0_iff:
wenzelm@61070
   769
  assumes in_Ints: "a \<in> \<int>"
haftmann@25919
   770
  shows "(a + a = 0) = (a = (0::'a::ring_char_0))"
haftmann@25919
   771
proof -
haftmann@25919
   772
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   773
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   774
  show ?thesis
haftmann@25919
   775
  proof
haftmann@25919
   776
    assume "a = 0"
haftmann@25919
   777
    thus "a + a = 0" by simp
haftmann@25919
   778
  next
haftmann@25919
   779
    assume eq: "a + a = 0"
haftmann@25919
   780
    hence "of_int (z + z) = (of_int 0 :: 'a)" by (simp add: a)
haftmann@25919
   781
    hence "z + z = 0" by (simp only: of_int_eq_iff)
haftmann@25919
   782
    hence "z = 0" by (simp only: double_eq_0_iff)
haftmann@25919
   783
    thus "a = 0" by (simp add: a)
haftmann@25919
   784
  qed
haftmann@25919
   785
qed
haftmann@25919
   786
haftmann@25919
   787
lemma Ints_odd_nonzero:
wenzelm@61070
   788
  assumes in_Ints: "a \<in> \<int>"
haftmann@25919
   789
  shows "1 + a + a \<noteq> (0::'a::ring_char_0)"
haftmann@25919
   790
proof -
haftmann@25919
   791
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   792
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   793
  show ?thesis
haftmann@25919
   794
  proof
haftmann@25919
   795
    assume eq: "1 + a + a = 0"
haftmann@25919
   796
    hence "of_int (1 + z + z) = (of_int 0 :: 'a)" by (simp add: a)
haftmann@25919
   797
    hence "1 + z + z = 0" by (simp only: of_int_eq_iff)
haftmann@25919
   798
    with odd_nonzero show False by blast
haftmann@25919
   799
  qed
lp15@60162
   800
qed
haftmann@25919
   801
wenzelm@61070
   802
lemma Nats_numeral [simp]: "numeral w \<in> \<nat>"
huffman@47108
   803
  using of_nat_in_Nats [of "numeral w"] by simp
huffman@35634
   804
lp15@60162
   805
lemma Ints_odd_less_0:
wenzelm@61070
   806
  assumes in_Ints: "a \<in> \<int>"
haftmann@35028
   807
  shows "(1 + a + a < 0) = (a < (0::'a::linordered_idom))"
haftmann@25919
   808
proof -
haftmann@25919
   809
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   810
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   811
  hence "((1::'a) + a + a < 0) = (of_int (1 + z + z) < (of_int 0 :: 'a))"
haftmann@25919
   812
    by (simp add: a)
huffman@45532
   813
  also have "... = (z < 0)" by (simp only: of_int_less_iff odd_less_0_iff)
haftmann@25919
   814
  also have "... = (a < 0)" by (simp add: a)
haftmann@25919
   815
  finally show ?thesis .
haftmann@25919
   816
qed
haftmann@25919
   817
haftmann@25919
   818
wenzelm@60758
   819
subsection \<open>@{term setsum} and @{term setprod}\<close>
haftmann@25919
   820
lp15@61649
   821
lemma of_nat_setsum [simp]: "of_nat (setsum f A) = (\<Sum>x\<in>A. of_nat(f x))"
haftmann@25919
   822
  apply (cases "finite A")
haftmann@25919
   823
  apply (erule finite_induct, auto)
haftmann@25919
   824
  done
haftmann@25919
   825
lp15@61649
   826
lemma of_int_setsum [simp]: "of_int (setsum f A) = (\<Sum>x\<in>A. of_int(f x))"
haftmann@25919
   827
  apply (cases "finite A")
haftmann@25919
   828
  apply (erule finite_induct, auto)
haftmann@25919
   829
  done
haftmann@25919
   830
lp15@61649
   831
lemma of_nat_setprod [simp]: "of_nat (setprod f A) = (\<Prod>x\<in>A. of_nat(f x))"
haftmann@25919
   832
  apply (cases "finite A")
haftmann@25919
   833
  apply (erule finite_induct, auto simp add: of_nat_mult)
haftmann@25919
   834
  done
haftmann@25919
   835
lp15@61649
   836
lemma of_int_setprod [simp]: "of_int (setprod f A) = (\<Prod>x\<in>A. of_int(f x))"
haftmann@25919
   837
  apply (cases "finite A")
haftmann@25919
   838
  apply (erule finite_induct, auto)
haftmann@25919
   839
  done
haftmann@25919
   840
haftmann@25919
   841
lemmas int_setsum = of_nat_setsum [where 'a=int]
haftmann@25919
   842
lemmas int_setprod = of_nat_setprod [where 'a=int]
haftmann@25919
   843
haftmann@25919
   844
wenzelm@60758
   845
text \<open>Legacy theorems\<close>
haftmann@25919
   846
haftmann@25919
   847
lemmas zle_int = of_nat_le_iff [where 'a=int]
haftmann@25919
   848
lemmas int_int_eq = of_nat_eq_iff [where 'a=int]
haftmann@25919
   849
wenzelm@60758
   850
subsection \<open>Setting up simplification procedures\<close>
huffman@30802
   851
haftmann@54249
   852
lemmas of_int_simps =
haftmann@54249
   853
  of_int_0 of_int_1 of_int_add of_int_mult
haftmann@54249
   854
wenzelm@48891
   855
ML_file "Tools/int_arith.ML"
wenzelm@60758
   856
declaration \<open>K Int_Arith.setup\<close>
haftmann@25919
   857
huffman@47108
   858
simproc_setup fast_arith ("(m::'a::linordered_idom) < n" |
wenzelm@61144
   859
  "(m::'a::linordered_idom) \<le> n" |
huffman@47108
   860
  "(m::'a::linordered_idom) = n") =
wenzelm@61144
   861
  \<open>K Lin_Arith.simproc\<close>
wenzelm@43595
   862
haftmann@25919
   863
wenzelm@60758
   864
subsection\<open>More Inequality Reasoning\<close>
haftmann@25919
   865
haftmann@25919
   866
lemma zless_add1_eq: "(w < z + (1::int)) = (w<z | w=z)"
haftmann@25919
   867
by arith
haftmann@25919
   868
haftmann@25919
   869
lemma add1_zle_eq: "(w + (1::int) \<le> z) = (w<z)"
haftmann@25919
   870
by arith
haftmann@25919
   871
haftmann@25919
   872
lemma zle_diff1_eq [simp]: "(w \<le> z - (1::int)) = (w<z)"
haftmann@25919
   873
by arith
haftmann@25919
   874
haftmann@25919
   875
lemma zle_add1_eq_le [simp]: "(w < z + (1::int)) = (w\<le>z)"
haftmann@25919
   876
by arith
haftmann@25919
   877
haftmann@25919
   878
lemma int_one_le_iff_zero_less: "((1::int) \<le> z) = (0 < z)"
haftmann@25919
   879
by arith
haftmann@25919
   880
haftmann@25919
   881
wenzelm@60758
   882
subsection\<open>The functions @{term nat} and @{term int}\<close>
haftmann@25919
   883
wenzelm@60758
   884
text\<open>Simplify the term @{term "w + - z"}\<close>
haftmann@25919
   885
haftmann@25919
   886
lemma one_less_nat_eq [simp]: "(Suc 0 < nat z) = (1 < z)"
lp15@60162
   887
  using zless_nat_conj [of 1 z] by auto
haftmann@25919
   888
wenzelm@60758
   889
text\<open>This simplifies expressions of the form @{term "int n = z"} where
wenzelm@60758
   890
      z is an integer literal.\<close>
huffman@47108
   891
lemmas int_eq_iff_numeral [simp] = int_eq_iff [of _ "numeral v"] for v
haftmann@25919
   892
haftmann@25919
   893
lemma split_nat [arith_split]:
huffman@44709
   894
  "P(nat(i::int)) = ((\<forall>n. i = int n \<longrightarrow> P n) & (i < 0 \<longrightarrow> P 0))"
haftmann@25919
   895
  (is "?P = (?L & ?R)")
haftmann@25919
   896
proof (cases "i < 0")
haftmann@25919
   897
  case True thus ?thesis by auto
haftmann@25919
   898
next
haftmann@25919
   899
  case False
haftmann@25919
   900
  have "?P = ?L"
haftmann@25919
   901
  proof
haftmann@25919
   902
    assume ?P thus ?L using False by clarsimp
haftmann@25919
   903
  next
haftmann@25919
   904
    assume ?L thus ?P using False by simp
haftmann@25919
   905
  qed
haftmann@25919
   906
  with False show ?thesis by simp
haftmann@25919
   907
qed
haftmann@25919
   908
hoelzl@59000
   909
lemma nat_abs_int_diff: "nat \<bar>int a - int b\<bar> = (if a \<le> b then b - a else a - b)"
hoelzl@59000
   910
  by auto
hoelzl@59000
   911
hoelzl@59000
   912
lemma nat_int_add: "nat (int a + int b) = a + b"
hoelzl@59000
   913
  by auto
hoelzl@59000
   914
haftmann@25919
   915
context ring_1
haftmann@25919
   916
begin
haftmann@25919
   917
blanchet@33056
   918
lemma of_int_of_nat [nitpick_simp]:
haftmann@25919
   919
  "of_int k = (if k < 0 then - of_nat (nat (- k)) else of_nat (nat k))"
haftmann@25919
   920
proof (cases "k < 0")
haftmann@25919
   921
  case True then have "0 \<le> - k" by simp
haftmann@25919
   922
  then have "of_nat (nat (- k)) = of_int (- k)" by (rule of_nat_nat)
haftmann@25919
   923
  with True show ?thesis by simp
haftmann@25919
   924
next
haftmann@25919
   925
  case False then show ?thesis by (simp add: not_less of_nat_nat)
haftmann@25919
   926
qed
haftmann@25919
   927
haftmann@25919
   928
end
haftmann@25919
   929
haftmann@25919
   930
lemma nat_mult_distrib:
haftmann@25919
   931
  fixes z z' :: int
haftmann@25919
   932
  assumes "0 \<le> z"
haftmann@25919
   933
  shows "nat (z * z') = nat z * nat z'"
haftmann@25919
   934
proof (cases "0 \<le> z'")
haftmann@25919
   935
  case False with assms have "z * z' \<le> 0"
haftmann@25919
   936
    by (simp add: not_le mult_le_0_iff)
haftmann@25919
   937
  then have "nat (z * z') = 0" by simp
haftmann@25919
   938
  moreover from False have "nat z' = 0" by simp
haftmann@25919
   939
  ultimately show ?thesis by simp
haftmann@25919
   940
next
haftmann@25919
   941
  case True with assms have ge_0: "z * z' \<ge> 0" by (simp add: zero_le_mult_iff)
haftmann@25919
   942
  show ?thesis
haftmann@25919
   943
    by (rule injD [of "of_nat :: nat \<Rightarrow> int", OF inj_of_nat])
haftmann@25919
   944
      (simp only: of_nat_mult of_nat_nat [OF True]
haftmann@25919
   945
         of_nat_nat [OF assms] of_nat_nat [OF ge_0], simp)
haftmann@25919
   946
qed
haftmann@25919
   947
haftmann@25919
   948
lemma nat_mult_distrib_neg: "z \<le> (0::int) ==> nat(z*z') = nat(-z) * nat(-z')"
haftmann@25919
   949
apply (rule trans)
haftmann@25919
   950
apply (rule_tac [2] nat_mult_distrib, auto)
haftmann@25919
   951
done
haftmann@25919
   952
wenzelm@61944
   953
lemma nat_abs_mult_distrib: "nat \<bar>w * z\<bar> = nat \<bar>w\<bar> * nat \<bar>z\<bar>"
haftmann@25919
   954
apply (cases "z=0 | w=0")
lp15@60162
   955
apply (auto simp add: abs_if nat_mult_distrib [symmetric]
haftmann@25919
   956
                      nat_mult_distrib_neg [symmetric] mult_less_0_iff)
haftmann@25919
   957
done
haftmann@25919
   958
haftmann@60570
   959
lemma int_in_range_abs [simp]:
haftmann@60570
   960
  "int n \<in> range abs"
haftmann@60570
   961
proof (rule range_eqI)
haftmann@60570
   962
  show "int n = \<bar>int n\<bar>"
haftmann@60570
   963
    by simp
haftmann@60570
   964
qed
haftmann@60570
   965
haftmann@60570
   966
lemma range_abs_Nats [simp]:
haftmann@60570
   967
  "range abs = (\<nat> :: int set)"
haftmann@60570
   968
proof -
haftmann@60570
   969
  have "\<bar>k\<bar> \<in> \<nat>" for k :: int
haftmann@60570
   970
    by (cases k) simp_all
haftmann@60570
   971
  moreover have "k \<in> range abs" if "k \<in> \<nat>" for k :: int
haftmann@60570
   972
    using that by induct simp
haftmann@60570
   973
  ultimately show ?thesis by blast
paulson@61204
   974
qed
haftmann@60570
   975
huffman@47207
   976
lemma Suc_nat_eq_nat_zadd1: "(0::int) <= z ==> Suc (nat z) = nat (1 + z)"
huffman@47207
   977
apply (rule sym)
huffman@47207
   978
apply (simp add: nat_eq_iff)
huffman@47207
   979
done
huffman@47207
   980
huffman@47207
   981
lemma diff_nat_eq_if:
lp15@60162
   982
     "nat z - nat z' =
lp15@60162
   983
        (if z' < 0 then nat z
lp15@60162
   984
         else let d = z-z' in
huffman@47207
   985
              if d < 0 then 0 else nat d)"
huffman@47207
   986
by (simp add: Let_def nat_diff_distrib [symmetric])
huffman@47207
   987
huffman@47207
   988
lemma nat_numeral_diff_1 [simp]:
huffman@47207
   989
  "numeral v - (1::nat) = nat (numeral v - 1)"
huffman@47207
   990
  using diff_nat_numeral [of v Num.One] by simp
huffman@47207
   991
haftmann@25919
   992
haftmann@25919
   993
subsection "Induction principles for int"
haftmann@25919
   994
wenzelm@60758
   995
text\<open>Well-founded segments of the integers\<close>
haftmann@25919
   996
haftmann@25919
   997
definition
haftmann@25919
   998
  int_ge_less_than  ::  "int => (int * int) set"
haftmann@25919
   999
where
haftmann@25919
  1000
  "int_ge_less_than d = {(z',z). d \<le> z' & z' < z}"
haftmann@25919
  1001
haftmann@25919
  1002
theorem wf_int_ge_less_than: "wf (int_ge_less_than d)"
haftmann@25919
  1003
proof -
haftmann@25919
  1004
  have "int_ge_less_than d \<subseteq> measure (%z. nat (z-d))"
haftmann@25919
  1005
    by (auto simp add: int_ge_less_than_def)
lp15@60162
  1006
  thus ?thesis
lp15@60162
  1007
    by (rule wf_subset [OF wf_measure])
haftmann@25919
  1008
qed
haftmann@25919
  1009
wenzelm@60758
  1010
text\<open>This variant looks odd, but is typical of the relations suggested
wenzelm@60758
  1011
by RankFinder.\<close>
haftmann@25919
  1012
haftmann@25919
  1013
definition
haftmann@25919
  1014
  int_ge_less_than2 ::  "int => (int * int) set"
haftmann@25919
  1015
where
haftmann@25919
  1016
  "int_ge_less_than2 d = {(z',z). d \<le> z & z' < z}"
haftmann@25919
  1017
haftmann@25919
  1018
theorem wf_int_ge_less_than2: "wf (int_ge_less_than2 d)"
haftmann@25919
  1019
proof -
lp15@60162
  1020
  have "int_ge_less_than2 d \<subseteq> measure (%z. nat (1+z-d))"
haftmann@25919
  1021
    by (auto simp add: int_ge_less_than2_def)
lp15@60162
  1022
  thus ?thesis
lp15@60162
  1023
    by (rule wf_subset [OF wf_measure])
haftmann@25919
  1024
qed
haftmann@25919
  1025
haftmann@25919
  1026
(* `set:int': dummy construction *)
haftmann@25919
  1027
theorem int_ge_induct [case_names base step, induct set: int]:
haftmann@25919
  1028
  fixes i :: int
haftmann@25919
  1029
  assumes ge: "k \<le> i" and
haftmann@25919
  1030
    base: "P k" and
haftmann@25919
  1031
    step: "\<And>i. k \<le> i \<Longrightarrow> P i \<Longrightarrow> P (i + 1)"
haftmann@25919
  1032
  shows "P i"
haftmann@25919
  1033
proof -
wenzelm@42676
  1034
  { fix n
wenzelm@42676
  1035
    have "\<And>i::int. n = nat (i - k) \<Longrightarrow> k \<le> i \<Longrightarrow> P i"
haftmann@25919
  1036
    proof (induct n)
haftmann@25919
  1037
      case 0
haftmann@25919
  1038
      hence "i = k" by arith
haftmann@25919
  1039
      thus "P i" using base by simp
haftmann@25919
  1040
    next
haftmann@25919
  1041
      case (Suc n)
haftmann@25919
  1042
      then have "n = nat((i - 1) - k)" by arith
haftmann@25919
  1043
      moreover
haftmann@25919
  1044
      have ki1: "k \<le> i - 1" using Suc.prems by arith
haftmann@25919
  1045
      ultimately
wenzelm@42676
  1046
      have "P (i - 1)" by (rule Suc.hyps)
wenzelm@42676
  1047
      from step [OF ki1 this] show ?case by simp
haftmann@25919
  1048
    qed
haftmann@25919
  1049
  }
haftmann@25919
  1050
  with ge show ?thesis by fast
haftmann@25919
  1051
qed
haftmann@25919
  1052
haftmann@25928
  1053
(* `set:int': dummy construction *)
haftmann@25928
  1054
theorem int_gr_induct [case_names base step, induct set: int]:
haftmann@25919
  1055
  assumes gr: "k < (i::int)" and
haftmann@25919
  1056
        base: "P(k+1)" and
haftmann@25919
  1057
        step: "\<And>i. \<lbrakk>k < i; P i\<rbrakk> \<Longrightarrow> P(i+1)"
haftmann@25919
  1058
  shows "P i"
haftmann@25919
  1059
apply(rule int_ge_induct[of "k + 1"])
haftmann@25919
  1060
  using gr apply arith
haftmann@25919
  1061
 apply(rule base)
haftmann@25919
  1062
apply (rule step, simp+)
haftmann@25919
  1063
done
haftmann@25919
  1064
wenzelm@42676
  1065
theorem int_le_induct [consumes 1, case_names base step]:
haftmann@25919
  1066
  assumes le: "i \<le> (k::int)" and
haftmann@25919
  1067
        base: "P(k)" and
haftmann@25919
  1068
        step: "\<And>i. \<lbrakk>i \<le> k; P i\<rbrakk> \<Longrightarrow> P(i - 1)"
haftmann@25919
  1069
  shows "P i"
haftmann@25919
  1070
proof -
wenzelm@42676
  1071
  { fix n
wenzelm@42676
  1072
    have "\<And>i::int. n = nat(k-i) \<Longrightarrow> i \<le> k \<Longrightarrow> P i"
haftmann@25919
  1073
    proof (induct n)
haftmann@25919
  1074
      case 0
haftmann@25919
  1075
      hence "i = k" by arith
haftmann@25919
  1076
      thus "P i" using base by simp
haftmann@25919
  1077
    next
haftmann@25919
  1078
      case (Suc n)
wenzelm@42676
  1079
      hence "n = nat (k - (i + 1))" by arith
haftmann@25919
  1080
      moreover
haftmann@25919
  1081
      have ki1: "i + 1 \<le> k" using Suc.prems by arith
haftmann@25919
  1082
      ultimately
wenzelm@42676
  1083
      have "P (i + 1)" by(rule Suc.hyps)
haftmann@25919
  1084
      from step[OF ki1 this] show ?case by simp
haftmann@25919
  1085
    qed
haftmann@25919
  1086
  }
haftmann@25919
  1087
  with le show ?thesis by fast
haftmann@25919
  1088
qed
haftmann@25919
  1089
wenzelm@42676
  1090
theorem int_less_induct [consumes 1, case_names base step]:
haftmann@25919
  1091
  assumes less: "(i::int) < k" and
haftmann@25919
  1092
        base: "P(k - 1)" and
haftmann@25919
  1093
        step: "\<And>i. \<lbrakk>i < k; P i\<rbrakk> \<Longrightarrow> P(i - 1)"
haftmann@25919
  1094
  shows "P i"
haftmann@25919
  1095
apply(rule int_le_induct[of _ "k - 1"])
haftmann@25919
  1096
  using less apply arith
haftmann@25919
  1097
 apply(rule base)
haftmann@25919
  1098
apply (rule step, simp+)
haftmann@25919
  1099
done
haftmann@25919
  1100
haftmann@36811
  1101
theorem int_induct [case_names base step1 step2]:
haftmann@36801
  1102
  fixes k :: int
haftmann@36801
  1103
  assumes base: "P k"
haftmann@36801
  1104
    and step1: "\<And>i. k \<le> i \<Longrightarrow> P i \<Longrightarrow> P (i + 1)"
haftmann@36801
  1105
    and step2: "\<And>i. k \<ge> i \<Longrightarrow> P i \<Longrightarrow> P (i - 1)"
haftmann@36801
  1106
  shows "P i"
haftmann@36801
  1107
proof -
haftmann@36801
  1108
  have "i \<le> k \<or> i \<ge> k" by arith
wenzelm@42676
  1109
  then show ?thesis
wenzelm@42676
  1110
  proof
wenzelm@42676
  1111
    assume "i \<ge> k"
wenzelm@42676
  1112
    then show ?thesis using base
haftmann@36801
  1113
      by (rule int_ge_induct) (fact step1)
haftmann@36801
  1114
  next
wenzelm@42676
  1115
    assume "i \<le> k"
wenzelm@42676
  1116
    then show ?thesis using base
haftmann@36801
  1117
      by (rule int_le_induct) (fact step2)
haftmann@36801
  1118
  qed
haftmann@36801
  1119
qed
haftmann@36801
  1120
wenzelm@60758
  1121
subsection\<open>Intermediate value theorems\<close>
haftmann@25919
  1122
haftmann@25919
  1123
lemma int_val_lemma:
wenzelm@61944
  1124
     "(\<forall>i<n::nat. \<bar>f(i+1) - f i\<bar> \<le> 1) -->
haftmann@25919
  1125
      f 0 \<le> k --> k \<le> f n --> (\<exists>i \<le> n. f i = (k::int))"
huffman@30079
  1126
unfolding One_nat_def
wenzelm@42676
  1127
apply (induct n)
wenzelm@42676
  1128
apply simp
haftmann@25919
  1129
apply (intro strip)
haftmann@25919
  1130
apply (erule impE, simp)
haftmann@25919
  1131
apply (erule_tac x = n in allE, simp)
huffman@30079
  1132
apply (case_tac "k = f (Suc n)")
haftmann@27106
  1133
apply force
haftmann@25919
  1134
apply (erule impE)
haftmann@25919
  1135
 apply (simp add: abs_if split add: split_if_asm)
haftmann@25919
  1136
apply (blast intro: le_SucI)
haftmann@25919
  1137
done
haftmann@25919
  1138
haftmann@25919
  1139
lemmas nat0_intermed_int_val = int_val_lemma [rule_format (no_asm)]
haftmann@25919
  1140
haftmann@25919
  1141
lemma nat_intermed_int_val:
wenzelm@61944
  1142
     "[| \<forall>i. m \<le> i & i < n --> \<bar>f(i + 1::nat) - f i\<bar> \<le> 1; m < n;
haftmann@25919
  1143
         f m \<le> k; k \<le> f n |] ==> ? i. m \<le> i & i \<le> n & f i = (k::int)"
lp15@60162
  1144
apply (cut_tac n = "n-m" and f = "%i. f (i+m) " and k = k
haftmann@25919
  1145
       in int_val_lemma)
huffman@30079
  1146
unfolding One_nat_def
haftmann@25919
  1147
apply simp
haftmann@25919
  1148
apply (erule exE)
haftmann@25919
  1149
apply (rule_tac x = "i+m" in exI, arith)
haftmann@25919
  1150
done
haftmann@25919
  1151
haftmann@25919
  1152
wenzelm@60758
  1153
subsection\<open>Products and 1, by T. M. Rasmussen\<close>
haftmann@25919
  1154
haftmann@25919
  1155
lemma zabs_less_one_iff [simp]: "(\<bar>z\<bar> < 1) = (z = (0::int))"
haftmann@25919
  1156
by arith
haftmann@25919
  1157
paulson@34055
  1158
lemma abs_zmult_eq_1:
paulson@34055
  1159
  assumes mn: "\<bar>m * n\<bar> = 1"
paulson@34055
  1160
  shows "\<bar>m\<bar> = (1::int)"
paulson@34055
  1161
proof -
paulson@34055
  1162
  have 0: "m \<noteq> 0 & n \<noteq> 0" using mn
paulson@34055
  1163
    by auto
paulson@34055
  1164
  have "~ (2 \<le> \<bar>m\<bar>)"
paulson@34055
  1165
  proof
paulson@34055
  1166
    assume "2 \<le> \<bar>m\<bar>"
paulson@34055
  1167
    hence "2*\<bar>n\<bar> \<le> \<bar>m\<bar>*\<bar>n\<bar>"
lp15@60162
  1168
      by (simp add: mult_mono 0)
lp15@60162
  1169
    also have "... = \<bar>m*n\<bar>"
paulson@34055
  1170
      by (simp add: abs_mult)
paulson@34055
  1171
    also have "... = 1"
paulson@34055
  1172
      by (simp add: mn)
paulson@34055
  1173
    finally have "2*\<bar>n\<bar> \<le> 1" .
paulson@34055
  1174
    thus "False" using 0
huffman@47108
  1175
      by arith
paulson@34055
  1176
  qed
paulson@34055
  1177
  thus ?thesis using 0
paulson@34055
  1178
    by auto
paulson@34055
  1179
qed
haftmann@25919
  1180
haftmann@25919
  1181
lemma pos_zmult_eq_1_iff_lemma: "(m * n = 1) ==> m = (1::int) | m = -1"
haftmann@25919
  1182
by (insert abs_zmult_eq_1 [of m n], arith)
haftmann@25919
  1183
boehmes@35815
  1184
lemma pos_zmult_eq_1_iff:
boehmes@35815
  1185
  assumes "0 < (m::int)" shows "(m * n = 1) = (m = 1 & n = 1)"
boehmes@35815
  1186
proof -
boehmes@35815
  1187
  from assms have "m * n = 1 ==> m = 1" by (auto dest: pos_zmult_eq_1_iff_lemma)
boehmes@35815
  1188
  thus ?thesis by (auto dest: pos_zmult_eq_1_iff_lemma)
boehmes@35815
  1189
qed
haftmann@25919
  1190
haftmann@25919
  1191
lemma zmult_eq_1_iff: "(m*n = (1::int)) = ((m = 1 & n = 1) | (m = -1 & n = -1))"
lp15@60162
  1192
apply (rule iffI)
haftmann@25919
  1193
 apply (frule pos_zmult_eq_1_iff_lemma)
lp15@60162
  1194
 apply (simp add: mult.commute [of m])
lp15@60162
  1195
 apply (frule pos_zmult_eq_1_iff_lemma, auto)
haftmann@25919
  1196
done
haftmann@25919
  1197
haftmann@33296
  1198
lemma infinite_UNIV_int: "\<not> finite (UNIV::int set)"
haftmann@25919
  1199
proof
haftmann@33296
  1200
  assume "finite (UNIV::int set)"
wenzelm@61076
  1201
  moreover have "inj (\<lambda>i::int. 2 * i)"
haftmann@33296
  1202
    by (rule injI) simp
wenzelm@61076
  1203
  ultimately have "surj (\<lambda>i::int. 2 * i)"
haftmann@33296
  1204
    by (rule finite_UNIV_inj_surj)
haftmann@33296
  1205
  then obtain i :: int where "1 = 2 * i" by (rule surjE)
haftmann@33296
  1206
  then show False by (simp add: pos_zmult_eq_1_iff)
haftmann@25919
  1207
qed
haftmann@25919
  1208
haftmann@25919
  1209
wenzelm@60758
  1210
subsection \<open>Further theorems on numerals\<close>
haftmann@30652
  1211
wenzelm@60758
  1212
subsubsection\<open>Special Simplification for Constants\<close>
haftmann@30652
  1213
wenzelm@60758
  1214
text\<open>These distributive laws move literals inside sums and differences.\<close>
haftmann@30652
  1215
webertj@49962
  1216
lemmas distrib_right_numeral [simp] = distrib_right [of _ _ "numeral v"] for v
webertj@49962
  1217
lemmas distrib_left_numeral [simp] = distrib_left [of "numeral v"] for v
huffman@47108
  1218
lemmas left_diff_distrib_numeral [simp] = left_diff_distrib [of _ _ "numeral v"] for v
huffman@47108
  1219
lemmas right_diff_distrib_numeral [simp] = right_diff_distrib [of "numeral v"] for v
haftmann@30652
  1220
wenzelm@60758
  1221
text\<open>These are actually for fields, like real: but where else to put them?\<close>
haftmann@30652
  1222
huffman@47108
  1223
lemmas zero_less_divide_iff_numeral [simp, no_atp] = zero_less_divide_iff [of "numeral w"] for w
huffman@47108
  1224
lemmas divide_less_0_iff_numeral [simp, no_atp] = divide_less_0_iff [of "numeral w"] for w
huffman@47108
  1225
lemmas zero_le_divide_iff_numeral [simp, no_atp] = zero_le_divide_iff [of "numeral w"] for w
huffman@47108
  1226
lemmas divide_le_0_iff_numeral [simp, no_atp] = divide_le_0_iff [of "numeral w"] for w
haftmann@30652
  1227
haftmann@30652
  1228
wenzelm@61799
  1229
text \<open>Replaces \<open>inverse #nn\<close> by \<open>1/#nn\<close>.  It looks
wenzelm@60758
  1230
  strange, but then other simprocs simplify the quotient.\<close>
haftmann@30652
  1231
huffman@47108
  1232
lemmas inverse_eq_divide_numeral [simp] =
huffman@47108
  1233
  inverse_eq_divide [of "numeral w"] for w
huffman@47108
  1234
huffman@47108
  1235
lemmas inverse_eq_divide_neg_numeral [simp] =
haftmann@54489
  1236
  inverse_eq_divide [of "- numeral w"] for w
haftmann@30652
  1237
wenzelm@60758
  1238
text \<open>These laws simplify inequalities, moving unary minus from a term
wenzelm@60758
  1239
into the literal.\<close>
haftmann@30652
  1240
haftmann@54489
  1241
lemmas equation_minus_iff_numeral [no_atp] =
haftmann@54489
  1242
  equation_minus_iff [of "numeral v"] for v
huffman@47108
  1243
haftmann@54489
  1244
lemmas minus_equation_iff_numeral [no_atp] =
haftmann@54489
  1245
  minus_equation_iff [of _ "numeral v"] for v
huffman@47108
  1246
haftmann@54489
  1247
lemmas le_minus_iff_numeral [no_atp] =
haftmann@54489
  1248
  le_minus_iff [of "numeral v"] for v
haftmann@30652
  1249
haftmann@54489
  1250
lemmas minus_le_iff_numeral [no_atp] =
haftmann@54489
  1251
  minus_le_iff [of _ "numeral v"] for v
haftmann@30652
  1252
haftmann@54489
  1253
lemmas less_minus_iff_numeral [no_atp] =
haftmann@54489
  1254
  less_minus_iff [of "numeral v"] for v
haftmann@30652
  1255
haftmann@54489
  1256
lemmas minus_less_iff_numeral [no_atp] =
haftmann@54489
  1257
  minus_less_iff [of _ "numeral v"] for v
haftmann@30652
  1258
wenzelm@61799
  1259
\<comment> \<open>FIXME maybe simproc\<close>
haftmann@30652
  1260
haftmann@30652
  1261
wenzelm@61799
  1262
text \<open>Cancellation of constant factors in comparisons (\<open><\<close> and \<open>\<le>\<close>)\<close>
haftmann@30652
  1263
huffman@47108
  1264
lemmas mult_less_cancel_left_numeral [simp, no_atp] = mult_less_cancel_left [of "numeral v"] for v
huffman@47108
  1265
lemmas mult_less_cancel_right_numeral [simp, no_atp] = mult_less_cancel_right [of _ "numeral v"] for v
huffman@47108
  1266
lemmas mult_le_cancel_left_numeral [simp, no_atp] = mult_le_cancel_left [of "numeral v"] for v
huffman@47108
  1267
lemmas mult_le_cancel_right_numeral [simp, no_atp] = mult_le_cancel_right [of _ "numeral v"] for v
haftmann@30652
  1268
haftmann@30652
  1269
wenzelm@61799
  1270
text \<open>Multiplying out constant divisors in comparisons (\<open><\<close>, \<open>\<le>\<close> and \<open>=\<close>)\<close>
haftmann@30652
  1271
lp15@61738
  1272
named_theorems divide_const_simps "simplification rules to simplify comparisons involving constant divisors"
lp15@61738
  1273
lp15@61738
  1274
lemmas le_divide_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1275
  pos_le_divide_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1276
  neg_le_divide_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1277
lp15@61738
  1278
lemmas divide_le_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1279
  pos_divide_le_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1280
  neg_divide_le_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1281
lp15@61738
  1282
lemmas less_divide_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1283
  pos_less_divide_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1284
  neg_less_divide_eq [of "- numeral w", OF neg_numeral_less_zero] for w
haftmann@30652
  1285
lp15@61738
  1286
lemmas divide_less_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1287
  pos_divide_less_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1288
  neg_divide_less_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1289
lp15@61738
  1290
lemmas eq_divide_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1291
  eq_divide_eq [of _ _ "numeral w"]
haftmann@54489
  1292
  eq_divide_eq [of _ _ "- numeral w"] for w
huffman@47108
  1293
lp15@61738
  1294
lemmas divide_eq_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1295
  divide_eq_eq [of _ "numeral w"]
haftmann@54489
  1296
  divide_eq_eq [of _ "- numeral w"] for w
haftmann@54489
  1297
haftmann@30652
  1298
wenzelm@60758
  1299
subsubsection\<open>Optional Simplification Rules Involving Constants\<close>
haftmann@30652
  1300
wenzelm@60758
  1301
text\<open>Simplify quotients that are compared with a literal constant.\<close>
haftmann@30652
  1302
lp15@61738
  1303
lemmas le_divide_eq_numeral [divide_const_simps] =
huffman@47108
  1304
  le_divide_eq [of "numeral w"]
haftmann@54489
  1305
  le_divide_eq [of "- numeral w"] for w
huffman@47108
  1306
lp15@61738
  1307
lemmas divide_le_eq_numeral [divide_const_simps] =
huffman@47108
  1308
  divide_le_eq [of _ _ "numeral w"]
haftmann@54489
  1309
  divide_le_eq [of _ _ "- numeral w"] for w
huffman@47108
  1310
lp15@61738
  1311
lemmas less_divide_eq_numeral [divide_const_simps] =
huffman@47108
  1312
  less_divide_eq [of "numeral w"]
haftmann@54489
  1313
  less_divide_eq [of "- numeral w"] for w
huffman@47108
  1314
lp15@61738
  1315
lemmas divide_less_eq_numeral [divide_const_simps] =
huffman@47108
  1316
  divide_less_eq [of _ _ "numeral w"]
haftmann@54489
  1317
  divide_less_eq [of _ _ "- numeral w"] for w
huffman@47108
  1318
lp15@61738
  1319
lemmas eq_divide_eq_numeral [divide_const_simps] =
huffman@47108
  1320
  eq_divide_eq [of "numeral w"]
haftmann@54489
  1321
  eq_divide_eq [of "- numeral w"] for w
huffman@47108
  1322
lp15@61738
  1323
lemmas divide_eq_eq_numeral [divide_const_simps] =
huffman@47108
  1324
  divide_eq_eq [of _ _ "numeral w"]
haftmann@54489
  1325
  divide_eq_eq [of _ _ "- numeral w"] for w
haftmann@30652
  1326
haftmann@30652
  1327
wenzelm@60758
  1328
text\<open>Not good as automatic simprules because they cause case splits.\<close>
lp15@61738
  1329
lemmas [divide_const_simps] = le_divide_eq_1 divide_le_eq_1 less_divide_eq_1 divide_less_eq_1 
haftmann@30652
  1330
haftmann@30652
  1331
wenzelm@60758
  1332
subsection \<open>The divides relation\<close>
haftmann@33320
  1333
nipkow@33657
  1334
lemma zdvd_antisym_nonneg:
nipkow@33657
  1335
    "0 <= m ==> 0 <= n ==> m dvd n ==> n dvd m ==> m = (n::int)"
haftmann@33320
  1336
  apply (simp add: dvd_def, auto)
haftmann@57512
  1337
  apply (auto simp add: mult.assoc zero_le_mult_iff zmult_eq_1_iff)
haftmann@33320
  1338
  done
haftmann@33320
  1339
lp15@60162
  1340
lemma zdvd_antisym_abs: assumes "(a::int) dvd b" and "b dvd a"
haftmann@33320
  1341
  shows "\<bar>a\<bar> = \<bar>b\<bar>"
nipkow@33657
  1342
proof cases
nipkow@33657
  1343
  assume "a = 0" with assms show ?thesis by simp
nipkow@33657
  1344
next
nipkow@33657
  1345
  assume "a \<noteq> 0"
wenzelm@60758
  1346
  from \<open>a dvd b\<close> obtain k where k:"b = a*k" unfolding dvd_def by blast
wenzelm@60758
  1347
  from \<open>b dvd a\<close> obtain k' where k':"a = b*k'" unfolding dvd_def by blast
haftmann@33320
  1348
  from k k' have "a = a*k*k'" by simp
haftmann@33320
  1349
  with mult_cancel_left1[where c="a" and b="k*k'"]
wenzelm@60758
  1350
  have kk':"k*k' = 1" using \<open>a\<noteq>0\<close> by (simp add: mult.assoc)
haftmann@33320
  1351
  hence "k = 1 \<and> k' = 1 \<or> k = -1 \<and> k' = -1" by (simp add: zmult_eq_1_iff)
haftmann@33320
  1352
  thus ?thesis using k k' by auto
haftmann@33320
  1353
qed
haftmann@33320
  1354
haftmann@33320
  1355
lemma zdvd_zdiffD: "k dvd m - n ==> k dvd n ==> k dvd (m::int)"
lp15@60162
  1356
  using dvd_add_right_iff [of k "- n" m] by simp
haftmann@33320
  1357
haftmann@33320
  1358
lemma zdvd_reduce: "(k dvd n + k * m) = (k dvd (n::int))"
haftmann@58649
  1359
  using dvd_add_times_triv_right_iff [of k n m] by (simp add: ac_simps)
haftmann@33320
  1360
haftmann@33320
  1361
lemma dvd_imp_le_int:
haftmann@33320
  1362
  fixes d i :: int
haftmann@33320
  1363
  assumes "i \<noteq> 0" and "d dvd i"
haftmann@33320
  1364
  shows "\<bar>d\<bar> \<le> \<bar>i\<bar>"
haftmann@33320
  1365
proof -
wenzelm@60758
  1366
  from \<open>d dvd i\<close> obtain k where "i = d * k" ..
wenzelm@60758
  1367
  with \<open>i \<noteq> 0\<close> have "k \<noteq> 0" by auto
haftmann@33320
  1368
  then have "1 \<le> \<bar>k\<bar>" and "0 \<le> \<bar>d\<bar>" by auto
haftmann@33320
  1369
  then have "\<bar>d\<bar> * 1 \<le> \<bar>d\<bar> * \<bar>k\<bar>" by (rule mult_left_mono)
wenzelm@60758
  1370
  with \<open>i = d * k\<close> show ?thesis by (simp add: abs_mult)
haftmann@33320
  1371
qed
haftmann@33320
  1372
haftmann@33320
  1373
lemma zdvd_not_zless:
haftmann@33320
  1374
  fixes m n :: int
haftmann@33320
  1375
  assumes "0 < m" and "m < n"
haftmann@33320
  1376
  shows "\<not> n dvd m"
haftmann@33320
  1377
proof
haftmann@33320
  1378
  from assms have "0 < n" by auto
haftmann@33320
  1379
  assume "n dvd m" then obtain k where k: "m = n * k" ..
wenzelm@60758
  1380
  with \<open>0 < m\<close> have "0 < n * k" by auto
wenzelm@60758
  1381
  with \<open>0 < n\<close> have "0 < k" by (simp add: zero_less_mult_iff)
wenzelm@60758
  1382
  with k \<open>0 < n\<close> \<open>m < n\<close> have "n * k < n * 1" by simp
wenzelm@60758
  1383
  with \<open>0 < n\<close> \<open>0 < k\<close> show False unfolding mult_less_cancel_left by auto
haftmann@33320
  1384
qed
haftmann@33320
  1385
haftmann@33320
  1386
lemma zdvd_mult_cancel: assumes d:"k * m dvd k * n" and kz:"k \<noteq> (0::int)"
haftmann@33320
  1387
  shows "m dvd n"
haftmann@33320
  1388
proof-
haftmann@33320
  1389
  from d obtain h where h: "k*n = k*m * h" unfolding dvd_def by blast
haftmann@33320
  1390
  {assume "n \<noteq> m*h" hence "k* n \<noteq> k* (m*h)" using kz by simp
haftmann@57512
  1391
    with h have False by (simp add: mult.assoc)}
haftmann@33320
  1392
  hence "n = m * h" by blast
haftmann@33320
  1393
  thus ?thesis by simp
haftmann@33320
  1394
qed
haftmann@33320
  1395
haftmann@33320
  1396
theorem zdvd_int: "(x dvd y) = (int x dvd int y)"
haftmann@33320
  1397
proof -
haftmann@33320
  1398
  have "\<And>k. int y = int x * k \<Longrightarrow> x dvd y"
haftmann@33320
  1399
  proof -
haftmann@33320
  1400
    fix k
haftmann@33320
  1401
    assume A: "int y = int x * k"
wenzelm@42676
  1402
    then show "x dvd y"
wenzelm@42676
  1403
    proof (cases k)
wenzelm@42676
  1404
      case (nonneg n)
lp15@61649
  1405
      with A have "y = x * n" by (simp del: of_nat_mult add: of_nat_mult [symmetric])
haftmann@33320
  1406
      then show ?thesis ..
haftmann@33320
  1407
    next
wenzelm@42676
  1408
      case (neg n)
wenzelm@42676
  1409
      with A have "int y = int x * (- int (Suc n))" by simp
haftmann@33320
  1410
      also have "\<dots> = - (int x * int (Suc n))" by (simp only: mult_minus_right)
haftmann@33320
  1411
      also have "\<dots> = - int (x * Suc n)" by (simp only: of_nat_mult [symmetric])
haftmann@33320
  1412
      finally have "- int (x * Suc n) = int y" ..
haftmann@33320
  1413
      then show ?thesis by (simp only: negative_eq_positive) auto
haftmann@33320
  1414
    qed
haftmann@33320
  1415
  qed
haftmann@33320
  1416
  then show ?thesis by (auto elim!: dvdE simp only: dvd_triv_left of_nat_mult)
haftmann@33320
  1417
qed
haftmann@33320
  1418
wenzelm@42676
  1419
lemma zdvd1_eq[simp]: "(x::int) dvd 1 = (\<bar>x\<bar> = 1)"
haftmann@33320
  1420
proof
haftmann@33320
  1421
  assume d: "x dvd 1" hence "int (nat \<bar>x\<bar>) dvd int (nat 1)" by simp
haftmann@33320
  1422
  hence "nat \<bar>x\<bar> dvd 1" by (simp add: zdvd_int)
haftmann@33320
  1423
  hence "nat \<bar>x\<bar> = 1"  by simp
wenzelm@42676
  1424
  thus "\<bar>x\<bar> = 1" by (cases "x < 0") auto
haftmann@33320
  1425
next
haftmann@33320
  1426
  assume "\<bar>x\<bar>=1"
haftmann@33320
  1427
  then have "x = 1 \<or> x = -1" by auto
haftmann@33320
  1428
  then show "x dvd 1" by (auto intro: dvdI)
haftmann@33320
  1429
qed
haftmann@33320
  1430
lp15@60162
  1431
lemma zdvd_mult_cancel1:
haftmann@33320
  1432
  assumes mp:"m \<noteq>(0::int)" shows "(m * n dvd m) = (\<bar>n\<bar> = 1)"
haftmann@33320
  1433
proof
lp15@60162
  1434
  assume n1: "\<bar>n\<bar> = 1" thus "m * n dvd m"
wenzelm@42676
  1435
    by (cases "n >0") (auto simp add: minus_equation_iff)
haftmann@33320
  1436
next
haftmann@33320
  1437
  assume H: "m * n dvd m" hence H2: "m * n dvd m * 1" by simp
haftmann@33320
  1438
  from zdvd_mult_cancel[OF H2 mp] show "\<bar>n\<bar> = 1" by (simp only: zdvd1_eq)
haftmann@33320
  1439
qed
haftmann@33320
  1440
wenzelm@61944
  1441
lemma int_dvd_iff: "(int m dvd z) = (m dvd nat \<bar>z\<bar>)"
haftmann@33320
  1442
  unfolding zdvd_int by (cases "z \<ge> 0") simp_all
haftmann@33320
  1443
wenzelm@61944
  1444
lemma dvd_int_iff: "(z dvd int m) = (nat \<bar>z\<bar> dvd m)"
haftmann@33320
  1445
  unfolding zdvd_int by (cases "z \<ge> 0") simp_all
haftmann@33320
  1446
haftmann@58650
  1447
lemma dvd_int_unfold_dvd_nat:
haftmann@58650
  1448
  "k dvd l \<longleftrightarrow> nat \<bar>k\<bar> dvd nat \<bar>l\<bar>"
haftmann@58650
  1449
  unfolding dvd_int_iff [symmetric] by simp
haftmann@58650
  1450
haftmann@33320
  1451
lemma nat_dvd_iff: "(nat z dvd m) = (if 0 \<le> z then (z dvd int m) else m = 0)"
haftmann@33320
  1452
  by (auto simp add: dvd_int_iff)
haftmann@33320
  1453
haftmann@33341
  1454
lemma eq_nat_nat_iff:
haftmann@33341
  1455
  "0 \<le> z \<Longrightarrow> 0 \<le> z' \<Longrightarrow> nat z = nat z' \<longleftrightarrow> z = z'"
haftmann@33341
  1456
  by (auto elim!: nonneg_eq_int)
haftmann@33341
  1457
haftmann@33341
  1458
lemma nat_power_eq:
haftmann@33341
  1459
  "0 \<le> z \<Longrightarrow> nat (z ^ n) = nat z ^ n"
haftmann@33341
  1460
  by (induct n) (simp_all add: nat_mult_distrib)
haftmann@33341
  1461
haftmann@33320
  1462
lemma zdvd_imp_le: "[| z dvd n; 0 < n |] ==> z \<le> (n::int)"
wenzelm@42676
  1463
  apply (cases n)
haftmann@33320
  1464
  apply (auto simp add: dvd_int_iff)
wenzelm@42676
  1465
  apply (cases z)
haftmann@33320
  1466
  apply (auto simp add: dvd_imp_le)
haftmann@33320
  1467
  done
haftmann@33320
  1468
haftmann@36749
  1469
lemma zdvd_period:
haftmann@36749
  1470
  fixes a d :: int
haftmann@36749
  1471
  assumes "a dvd d"
haftmann@36749
  1472
  shows "a dvd (x + t) \<longleftrightarrow> a dvd ((x + c * d) + t)"
haftmann@36749
  1473
proof -
haftmann@36749
  1474
  from assms obtain k where "d = a * k" by (rule dvdE)
wenzelm@42676
  1475
  show ?thesis
wenzelm@42676
  1476
  proof
haftmann@36749
  1477
    assume "a dvd (x + t)"
haftmann@36749
  1478
    then obtain l where "x + t = a * l" by (rule dvdE)
haftmann@36749
  1479
    then have "x = a * l - t" by simp
wenzelm@60758
  1480
    with \<open>d = a * k\<close> show "a dvd x + c * d + t" by simp
haftmann@36749
  1481
  next
haftmann@36749
  1482
    assume "a dvd x + c * d + t"
haftmann@36749
  1483
    then obtain l where "x + c * d + t = a * l" by (rule dvdE)
haftmann@36749
  1484
    then have "x = a * l - c * d - t" by simp
wenzelm@60758
  1485
    with \<open>d = a * k\<close> show "a dvd (x + t)" by simp
haftmann@36749
  1486
  qed
haftmann@36749
  1487
qed
haftmann@36749
  1488
haftmann@33320
  1489
wenzelm@60758
  1490
subsection \<open>Finiteness of intervals\<close>
bulwahn@46756
  1491
bulwahn@46756
  1492
lemma finite_interval_int1 [iff]: "finite {i :: int. a <= i & i <= b}"
bulwahn@46756
  1493
proof (cases "a <= b")
bulwahn@46756
  1494
  case True
bulwahn@46756
  1495
  from this show ?thesis
bulwahn@46756
  1496
  proof (induct b rule: int_ge_induct)
bulwahn@46756
  1497
    case base
bulwahn@46756
  1498
    have "{i. a <= i & i <= a} = {a}" by auto
bulwahn@46756
  1499
    from this show ?case by simp
bulwahn@46756
  1500
  next
bulwahn@46756
  1501
    case (step b)
bulwahn@46756
  1502
    from this have "{i. a <= i & i <= b + 1} = {i. a <= i & i <= b} \<union> {b + 1}" by auto
bulwahn@46756
  1503
    from this step show ?case by simp
bulwahn@46756
  1504
  qed
bulwahn@46756
  1505
next
bulwahn@46756
  1506
  case False from this show ?thesis
bulwahn@46756
  1507
    by (metis (lifting, no_types) Collect_empty_eq finite.emptyI order_trans)
bulwahn@46756
  1508
qed
bulwahn@46756
  1509
bulwahn@46756
  1510
lemma finite_interval_int2 [iff]: "finite {i :: int. a <= i & i < b}"
bulwahn@46756
  1511
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1512
bulwahn@46756
  1513
lemma finite_interval_int3 [iff]: "finite {i :: int. a < i & i <= b}"
bulwahn@46756
  1514
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1515
bulwahn@46756
  1516
lemma finite_interval_int4 [iff]: "finite {i :: int. a < i & i < b}"
bulwahn@46756
  1517
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1518
bulwahn@46756
  1519
wenzelm@60758
  1520
subsection \<open>Configuration of the code generator\<close>
haftmann@25919
  1521
wenzelm@60758
  1522
text \<open>Constructors\<close>
huffman@47108
  1523
huffman@47108
  1524
definition Pos :: "num \<Rightarrow> int" where
huffman@47108
  1525
  [simp, code_abbrev]: "Pos = numeral"
huffman@47108
  1526
huffman@47108
  1527
definition Neg :: "num \<Rightarrow> int" where
haftmann@54489
  1528
  [simp, code_abbrev]: "Neg n = - (Pos n)"
huffman@47108
  1529
huffman@47108
  1530
code_datatype "0::int" Pos Neg
huffman@47108
  1531
huffman@47108
  1532
wenzelm@60758
  1533
text \<open>Auxiliary operations\<close>
huffman@47108
  1534
huffman@47108
  1535
definition dup :: "int \<Rightarrow> int" where
huffman@47108
  1536
  [simp]: "dup k = k + k"
haftmann@26507
  1537
huffman@47108
  1538
lemma dup_code [code]:
huffman@47108
  1539
  "dup 0 = 0"
huffman@47108
  1540
  "dup (Pos n) = Pos (Num.Bit0 n)"
huffman@47108
  1541
  "dup (Neg n) = Neg (Num.Bit0 n)"
haftmann@54489
  1542
  unfolding Pos_def Neg_def
huffman@47108
  1543
  by (simp_all add: numeral_Bit0)
huffman@47108
  1544
huffman@47108
  1545
definition sub :: "num \<Rightarrow> num \<Rightarrow> int" where
huffman@47108
  1546
  [simp]: "sub m n = numeral m - numeral n"
haftmann@26507
  1547
huffman@47108
  1548
lemma sub_code [code]:
huffman@47108
  1549
  "sub Num.One Num.One = 0"
huffman@47108
  1550
  "sub (Num.Bit0 m) Num.One = Pos (Num.BitM m)"
huffman@47108
  1551
  "sub (Num.Bit1 m) Num.One = Pos (Num.Bit0 m)"
huffman@47108
  1552
  "sub Num.One (Num.Bit0 n) = Neg (Num.BitM n)"
huffman@47108
  1553
  "sub Num.One (Num.Bit1 n) = Neg (Num.Bit0 n)"
huffman@47108
  1554
  "sub (Num.Bit0 m) (Num.Bit0 n) = dup (sub m n)"
huffman@47108
  1555
  "sub (Num.Bit1 m) (Num.Bit1 n) = dup (sub m n)"
huffman@47108
  1556
  "sub (Num.Bit1 m) (Num.Bit0 n) = dup (sub m n) + 1"
huffman@47108
  1557
  "sub (Num.Bit0 m) (Num.Bit1 n) = dup (sub m n) - 1"
haftmann@54489
  1558
  apply (simp_all only: sub_def dup_def numeral.simps Pos_def Neg_def numeral_BitM)
haftmann@54230
  1559
  apply (simp_all only: algebra_simps minus_diff_eq)
haftmann@54230
  1560
  apply (simp_all only: add.commute [of _ "- (numeral n + numeral n)"])
haftmann@54230
  1561
  apply (simp_all only: minus_add add.assoc left_minus)
haftmann@54230
  1562
  done
huffman@47108
  1563
wenzelm@60758
  1564
text \<open>Implementations\<close>
huffman@47108
  1565
huffman@47108
  1566
lemma one_int_code [code, code_unfold]:
huffman@47108
  1567
  "1 = Pos Num.One"
huffman@47108
  1568
  by simp
huffman@47108
  1569
huffman@47108
  1570
lemma plus_int_code [code]:
huffman@47108
  1571
  "k + 0 = (k::int)"
huffman@47108
  1572
  "0 + l = (l::int)"
huffman@47108
  1573
  "Pos m + Pos n = Pos (m + n)"
huffman@47108
  1574
  "Pos m + Neg n = sub m n"
huffman@47108
  1575
  "Neg m + Pos n = sub n m"
huffman@47108
  1576
  "Neg m + Neg n = Neg (m + n)"
huffman@47108
  1577
  by simp_all
haftmann@26507
  1578
huffman@47108
  1579
lemma uminus_int_code [code]:
huffman@47108
  1580
  "uminus 0 = (0::int)"
huffman@47108
  1581
  "uminus (Pos m) = Neg m"
huffman@47108
  1582
  "uminus (Neg m) = Pos m"
huffman@47108
  1583
  by simp_all
huffman@47108
  1584
huffman@47108
  1585
lemma minus_int_code [code]:
huffman@47108
  1586
  "k - 0 = (k::int)"
huffman@47108
  1587
  "0 - l = uminus (l::int)"
huffman@47108
  1588
  "Pos m - Pos n = sub m n"
huffman@47108
  1589
  "Pos m - Neg n = Pos (m + n)"
huffman@47108
  1590
  "Neg m - Pos n = Neg (m + n)"
huffman@47108
  1591
  "Neg m - Neg n = sub n m"
huffman@47108
  1592
  by simp_all
huffman@47108
  1593
huffman@47108
  1594
lemma times_int_code [code]:
huffman@47108
  1595
  "k * 0 = (0::int)"
huffman@47108
  1596
  "0 * l = (0::int)"
huffman@47108
  1597
  "Pos m * Pos n = Pos (m * n)"
huffman@47108
  1598
  "Pos m * Neg n = Neg (m * n)"
huffman@47108
  1599
  "Neg m * Pos n = Neg (m * n)"
huffman@47108
  1600
  "Neg m * Neg n = Pos (m * n)"
huffman@47108
  1601
  by simp_all
haftmann@26507
  1602
haftmann@38857
  1603
instantiation int :: equal
haftmann@26507
  1604
begin
haftmann@26507
  1605
haftmann@37767
  1606
definition
huffman@47108
  1607
  "HOL.equal k l \<longleftrightarrow> k = (l::int)"
haftmann@38857
  1608
wenzelm@61169
  1609
instance
wenzelm@61169
  1610
  by standard (rule equal_int_def)
haftmann@26507
  1611
haftmann@26507
  1612
end
haftmann@26507
  1613
huffman@47108
  1614
lemma equal_int_code [code]:
huffman@47108
  1615
  "HOL.equal 0 (0::int) \<longleftrightarrow> True"
huffman@47108
  1616
  "HOL.equal 0 (Pos l) \<longleftrightarrow> False"
huffman@47108
  1617
  "HOL.equal 0 (Neg l) \<longleftrightarrow> False"
huffman@47108
  1618
  "HOL.equal (Pos k) 0 \<longleftrightarrow> False"
huffman@47108
  1619
  "HOL.equal (Pos k) (Pos l) \<longleftrightarrow> HOL.equal k l"
huffman@47108
  1620
  "HOL.equal (Pos k) (Neg l) \<longleftrightarrow> False"
huffman@47108
  1621
  "HOL.equal (Neg k) 0 \<longleftrightarrow> False"
huffman@47108
  1622
  "HOL.equal (Neg k) (Pos l) \<longleftrightarrow> False"
huffman@47108
  1623
  "HOL.equal (Neg k) (Neg l) \<longleftrightarrow> HOL.equal k l"
huffman@47108
  1624
  by (auto simp add: equal)
haftmann@26507
  1625
huffman@47108
  1626
lemma equal_int_refl [code nbe]:
haftmann@38857
  1627
  "HOL.equal (k::int) k \<longleftrightarrow> True"
huffman@47108
  1628
  by (fact equal_refl)
haftmann@26507
  1629
haftmann@28562
  1630
lemma less_eq_int_code [code]:
huffman@47108
  1631
  "0 \<le> (0::int) \<longleftrightarrow> True"
huffman@47108
  1632
  "0 \<le> Pos l \<longleftrightarrow> True"
huffman@47108
  1633
  "0 \<le> Neg l \<longleftrightarrow> False"
huffman@47108
  1634
  "Pos k \<le> 0 \<longleftrightarrow> False"
huffman@47108
  1635
  "Pos k \<le> Pos l \<longleftrightarrow> k \<le> l"
huffman@47108
  1636
  "Pos k \<le> Neg l \<longleftrightarrow> False"
huffman@47108
  1637
  "Neg k \<le> 0 \<longleftrightarrow> True"
huffman@47108
  1638
  "Neg k \<le> Pos l \<longleftrightarrow> True"
huffman@47108
  1639
  "Neg k \<le> Neg l \<longleftrightarrow> l \<le> k"
huffman@28958
  1640
  by simp_all
haftmann@26507
  1641
haftmann@28562
  1642
lemma less_int_code [code]:
huffman@47108
  1643
  "0 < (0::int) \<longleftrightarrow> False"
huffman@47108
  1644
  "0 < Pos l \<longleftrightarrow> True"
huffman@47108
  1645
  "0 < Neg l \<longleftrightarrow> False"
huffman@47108
  1646
  "Pos k < 0 \<longleftrightarrow> False"
huffman@47108
  1647
  "Pos k < Pos l \<longleftrightarrow> k < l"
huffman@47108
  1648
  "Pos k < Neg l \<longleftrightarrow> False"
huffman@47108
  1649
  "Neg k < 0 \<longleftrightarrow> True"
huffman@47108
  1650
  "Neg k < Pos l \<longleftrightarrow> True"
huffman@47108
  1651
  "Neg k < Neg l \<longleftrightarrow> l < k"
huffman@28958
  1652
  by simp_all
haftmann@25919
  1653
huffman@47108
  1654
lemma nat_code [code]:
huffman@47108
  1655
  "nat (Int.Neg k) = 0"
huffman@47108
  1656
  "nat 0 = 0"
huffman@47108
  1657
  "nat (Int.Pos k) = nat_of_num k"
haftmann@54489
  1658
  by (simp_all add: nat_of_num_numeral)
haftmann@25928
  1659
huffman@47108
  1660
lemma (in ring_1) of_int_code [code]:
haftmann@54489
  1661
  "of_int (Int.Neg k) = - numeral k"
huffman@47108
  1662
  "of_int 0 = 0"
huffman@47108
  1663
  "of_int (Int.Pos k) = numeral k"
huffman@47108
  1664
  by simp_all
haftmann@25919
  1665
huffman@47108
  1666
wenzelm@60758
  1667
text \<open>Serializer setup\<close>
haftmann@25919
  1668
haftmann@52435
  1669
code_identifier
haftmann@52435
  1670
  code_module Int \<rightharpoonup> (SML) Arith and (OCaml) Arith and (Haskell) Arith
haftmann@25919
  1671
haftmann@25919
  1672
quickcheck_params [default_type = int]
haftmann@25919
  1673
huffman@47108
  1674
hide_const (open) Pos Neg sub dup
haftmann@25919
  1675
haftmann@25919
  1676
wenzelm@60758
  1677
subsection \<open>Legacy theorems\<close>
haftmann@25919
  1678
haftmann@25919
  1679
lemmas inj_int = inj_of_nat [where 'a=int]
haftmann@25919
  1680
lemmas zadd_int = of_nat_add [where 'a=int, symmetric]
haftmann@25919
  1681
lemmas int_mult = of_nat_mult [where 'a=int]
wenzelm@45607
  1682
lemmas int_eq_0_conv = of_nat_eq_0_iff [where 'a=int and m="n"] for n
haftmann@25919
  1683
lemmas zless_int = of_nat_less_iff [where 'a=int]
wenzelm@45607
  1684
lemmas int_less_0_conv = of_nat_less_0_iff [where 'a=int and m="k"] for k
haftmann@25919
  1685
lemmas zero_less_int_conv = of_nat_0_less_iff [where 'a=int]
haftmann@25919
  1686
lemmas zero_zle_int = of_nat_0_le_iff [where 'a=int]
wenzelm@45607
  1687
lemmas int_le_0_conv = of_nat_le_0_iff [where 'a=int and m="n"] for n
haftmann@25919
  1688
lemmas int_0 = of_nat_0 [where 'a=int]
haftmann@25919
  1689
lemmas int_1 = of_nat_1 [where 'a=int]
haftmann@25919
  1690
lemmas int_Suc = of_nat_Suc [where 'a=int]
huffman@47207
  1691
lemmas int_numeral = of_nat_numeral [where 'a=int]
wenzelm@45607
  1692
lemmas abs_int_eq = abs_of_nat [where 'a=int and n="m"] for m
haftmann@25919
  1693
lemmas of_int_int_eq = of_int_of_nat_eq [where 'a=int]
haftmann@25919
  1694
lemmas zdiff_int = of_nat_diff [where 'a=int, symmetric]
huffman@47255
  1695
lemmas zpower_numeral_even = power_numeral_even [where 'a=int]
huffman@47255
  1696
lemmas zpower_numeral_odd = power_numeral_odd [where 'a=int]
haftmann@30960
  1697
wenzelm@61799
  1698
text \<open>De-register \<open>int\<close> as a quotient type:\<close>
huffman@48045
  1699
kuncar@53652
  1700
lifting_update int.lifting
kuncar@53652
  1701
lifting_forget int.lifting
huffman@48045
  1702
wenzelm@60758
  1703
text\<open>Also the class for fields with characteristic zero.\<close>
lp15@59667
  1704
class field_char_0 = field + ring_char_0
lp15@59667
  1705
subclass (in linordered_field) field_char_0 ..
lp15@59667
  1706
haftmann@25919
  1707
end