src/HOL/Int.thy
author nipkow
Tue Feb 23 16:25:08 2016 +0100 (2016-02-23)
changeset 62390 842917225d56
parent 62348 9a5f43dac883
child 63539 70d4d9e5707b
permissions -rw-r--r--
more canonical names
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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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lemma zabs_less_one_iff [simp]:
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  fixes z :: int
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  shows "\<bar>z\<bar> < 1 \<longleftrightarrow> z = 0" (is "?P \<longleftrightarrow> ?Q")
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proof
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  assume ?Q then show ?P by simp
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next
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  assume ?P
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  with zless_imp_add1_zle [of "\<bar>z\<bar>" 1] have "\<bar>z\<bar> + 1 \<le> 1"
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    by simp
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  then have "\<bar>z\<bar> \<le> 0"
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    by simp
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  then show ?Q
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    by simp
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qed
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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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lemma of_int_abs [simp]:
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  "of_int \<bar>x\<bar> = \<bar>of_int x\<bar>"
haftmann@62347
   340
  by (auto simp add: abs_if)
haftmann@62347
   341
haftmann@62347
   342
lemma of_int_lessD:
haftmann@62347
   343
  assumes "\<bar>of_int n\<bar> < x"
haftmann@62347
   344
  shows "n = 0 \<or> x > 1"
haftmann@62347
   345
proof (cases "n = 0")
haftmann@62347
   346
  case True then show ?thesis by simp
haftmann@62347
   347
next
haftmann@62347
   348
  case False
haftmann@62347
   349
  then have "\<bar>n\<bar> \<noteq> 0" by simp
haftmann@62347
   350
  then have "\<bar>n\<bar> > 0" by simp
haftmann@62347
   351
  then have "\<bar>n\<bar> \<ge> 1"
haftmann@62347
   352
    using zless_imp_add1_zle [of 0 "\<bar>n\<bar>"] by simp
haftmann@62347
   353
  then have "\<bar>of_int n\<bar> \<ge> 1"
haftmann@62347
   354
    unfolding of_int_1_le_iff [of "\<bar>n\<bar>", symmetric] by simp
haftmann@62347
   355
  then have "1 < x" using assms by (rule le_less_trans)
haftmann@62347
   356
  then show ?thesis ..
haftmann@62347
   357
qed
haftmann@62347
   358
haftmann@62347
   359
lemma of_int_leD:
haftmann@62347
   360
  assumes "\<bar>of_int n\<bar> \<le> x"
haftmann@62347
   361
  shows "n = 0 \<or> 1 \<le> x"
haftmann@62347
   362
proof (cases "n = 0")
haftmann@62347
   363
  case True then show ?thesis by simp
haftmann@62347
   364
next
haftmann@62347
   365
  case False
haftmann@62347
   366
  then have "\<bar>n\<bar> \<noteq> 0" by simp
haftmann@62347
   367
  then have "\<bar>n\<bar> > 0" by simp
haftmann@62347
   368
  then have "\<bar>n\<bar> \<ge> 1"
haftmann@62347
   369
    using zless_imp_add1_zle [of 0 "\<bar>n\<bar>"] by simp
haftmann@62347
   370
  then have "\<bar>of_int n\<bar> \<ge> 1"
haftmann@62347
   371
    unfolding of_int_1_le_iff [of "\<bar>n\<bar>", symmetric] by simp
haftmann@62347
   372
  then have "1 \<le> x" using assms by (rule order_trans)
haftmann@62347
   373
  then show ?thesis ..
haftmann@62347
   374
qed
haftmann@62347
   375
haftmann@62347
   376
haftmann@36424
   377
end
haftmann@25919
   378
lp15@61234
   379
text \<open>Comparisons involving @{term of_int}.\<close>
lp15@61234
   380
lp15@61234
   381
lemma of_int_eq_numeral_iff [iff]:
lp15@61649
   382
   "of_int z = (numeral n :: 'a::ring_char_0)
lp15@61234
   383
   \<longleftrightarrow> z = numeral n"
lp15@61234
   384
  using of_int_eq_iff by fastforce
lp15@61234
   385
lp15@61649
   386
lemma of_int_le_numeral_iff [simp]:
lp15@61649
   387
   "of_int z \<le> (numeral n :: 'a::linordered_idom)
lp15@61234
   388
   \<longleftrightarrow> z \<le> numeral n"
lp15@61234
   389
  using of_int_le_iff [of z "numeral n"] by simp
lp15@61234
   390
lp15@61649
   391
lemma of_int_numeral_le_iff [simp]:
lp15@61234
   392
   "(numeral n :: 'a::linordered_idom) \<le> of_int z \<longleftrightarrow> numeral n \<le> z"
lp15@61234
   393
  using of_int_le_iff [of "numeral n"] by simp
lp15@61234
   394
lp15@61649
   395
lemma of_int_less_numeral_iff [simp]:
lp15@61649
   396
   "of_int z < (numeral n :: 'a::linordered_idom)
lp15@61234
   397
   \<longleftrightarrow> z < numeral n"
lp15@61234
   398
  using of_int_less_iff [of z "numeral n"] by simp
lp15@61234
   399
lp15@61649
   400
lemma of_int_numeral_less_iff [simp]:
lp15@61234
   401
   "(numeral n :: 'a::linordered_idom) < of_int z \<longleftrightarrow> numeral n < z"
lp15@61234
   402
  using of_int_less_iff [of "numeral n" z] by simp
lp15@61234
   403
hoelzl@56889
   404
lemma of_nat_less_of_int_iff:
hoelzl@56889
   405
  "(of_nat n::'a::linordered_idom) < of_int x \<longleftrightarrow> int n < x"
hoelzl@56889
   406
  by (metis of_int_of_nat_eq of_int_less_iff)
hoelzl@56889
   407
haftmann@25919
   408
lemma of_int_eq_id [simp]: "of_int = id"
haftmann@25919
   409
proof
haftmann@25919
   410
  fix z show "of_int z = id z"
huffman@48045
   411
    by (cases z rule: int_diff_cases, simp)
haftmann@25919
   412
qed
haftmann@25919
   413
haftmann@25919
   414
hoelzl@51329
   415
instance int :: no_top
wenzelm@61169
   416
  apply standard
hoelzl@51329
   417
  apply (rule_tac x="x + 1" in exI)
hoelzl@51329
   418
  apply simp
hoelzl@51329
   419
  done
hoelzl@51329
   420
hoelzl@51329
   421
instance int :: no_bot
wenzelm@61169
   422
  apply standard
hoelzl@51329
   423
  apply (rule_tac x="x - 1" in exI)
hoelzl@51329
   424
  apply simp
hoelzl@51329
   425
  done
hoelzl@51329
   426
wenzelm@61799
   427
subsection \<open>Magnitude of an Integer, as a Natural Number: \<open>nat\<close>\<close>
haftmann@25919
   428
huffman@48045
   429
lift_definition nat :: "int \<Rightarrow> nat" is "\<lambda>(x, y). x - y"
huffman@48045
   430
  by auto
haftmann@25919
   431
huffman@44709
   432
lemma nat_int [simp]: "nat (int n) = n"
huffman@48045
   433
  by transfer simp
haftmann@25919
   434
huffman@44709
   435
lemma int_nat_eq [simp]: "int (nat z) = (if 0 \<le> z then z else 0)"
huffman@48045
   436
  by transfer clarsimp
haftmann@25919
   437
huffman@44709
   438
corollary nat_0_le: "0 \<le> z ==> int (nat z) = z"
haftmann@25919
   439
by simp
haftmann@25919
   440
haftmann@25919
   441
lemma nat_le_0 [simp]: "z \<le> 0 ==> nat z = 0"
huffman@48045
   442
  by transfer clarsimp
haftmann@25919
   443
haftmann@25919
   444
lemma nat_le_eq_zle: "0 < w | 0 \<le> z ==> (nat w \<le> nat z) = (w\<le>z)"
huffman@48045
   445
  by transfer (clarsimp, arith)
haftmann@25919
   446
wenzelm@60758
   447
text\<open>An alternative condition is @{term "0 \<le> w"}\<close>
haftmann@25919
   448
corollary nat_mono_iff: "0 < z ==> (nat w < nat z) = (w < z)"
lp15@60162
   449
by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
haftmann@25919
   450
haftmann@25919
   451
corollary nat_less_eq_zless: "0 \<le> w ==> (nat w < nat z) = (w<z)"
lp15@60162
   452
by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
haftmann@25919
   453
haftmann@25919
   454
lemma zless_nat_conj [simp]: "(nat w < nat z) = (0 < z & w < z)"
huffman@48045
   455
  by transfer (clarsimp, arith)
haftmann@25919
   456
haftmann@25919
   457
lemma nonneg_eq_int:
haftmann@25919
   458
  fixes z :: int
huffman@44709
   459
  assumes "0 \<le> z" and "\<And>m. z = int m \<Longrightarrow> P"
haftmann@25919
   460
  shows P
haftmann@25919
   461
  using assms by (blast dest: nat_0_le sym)
haftmann@25919
   462
haftmann@54223
   463
lemma nat_eq_iff:
haftmann@54223
   464
  "nat w = m \<longleftrightarrow> (if 0 \<le> w then w = int m else m = 0)"
huffman@48045
   465
  by transfer (clarsimp simp add: le_imp_diff_is_add)
lp15@60162
   466
haftmann@54223
   467
corollary nat_eq_iff2:
haftmann@54223
   468
  "m = nat w \<longleftrightarrow> (if 0 \<le> w then w = int m else m = 0)"
haftmann@54223
   469
  using nat_eq_iff [of w m] by auto
haftmann@54223
   470
haftmann@54223
   471
lemma nat_0 [simp]:
haftmann@54223
   472
  "nat 0 = 0"
haftmann@54223
   473
  by (simp add: nat_eq_iff)
haftmann@25919
   474
haftmann@54223
   475
lemma nat_1 [simp]:
haftmann@54223
   476
  "nat 1 = Suc 0"
haftmann@54223
   477
  by (simp add: nat_eq_iff)
haftmann@54223
   478
haftmann@54223
   479
lemma nat_numeral [simp]:
haftmann@54223
   480
  "nat (numeral k) = numeral k"
haftmann@54223
   481
  by (simp add: nat_eq_iff)
haftmann@25919
   482
haftmann@54223
   483
lemma nat_neg_numeral [simp]:
haftmann@54489
   484
  "nat (- numeral k) = 0"
haftmann@54223
   485
  by simp
haftmann@54223
   486
haftmann@54223
   487
lemma nat_2: "nat 2 = Suc (Suc 0)"
haftmann@54223
   488
  by simp
lp15@60162
   489
haftmann@25919
   490
lemma nat_less_iff: "0 \<le> w ==> (nat w < m) = (w < of_nat m)"
huffman@48045
   491
  by transfer (clarsimp, arith)
haftmann@25919
   492
huffman@44709
   493
lemma nat_le_iff: "nat x \<le> n \<longleftrightarrow> x \<le> int n"
huffman@48045
   494
  by transfer (clarsimp simp add: le_diff_conv)
huffman@44707
   495
huffman@44707
   496
lemma nat_mono: "x \<le> y \<Longrightarrow> nat x \<le> nat y"
huffman@48045
   497
  by transfer auto
huffman@44707
   498
nipkow@29700
   499
lemma nat_0_iff[simp]: "nat(i::int) = 0 \<longleftrightarrow> i\<le>0"
huffman@48045
   500
  by transfer clarsimp
nipkow@29700
   501
haftmann@25919
   502
lemma int_eq_iff: "(of_nat m = z) = (m = nat z & 0 \<le> z)"
haftmann@25919
   503
by (auto simp add: nat_eq_iff2)
haftmann@25919
   504
haftmann@25919
   505
lemma zero_less_nat_eq [simp]: "(0 < nat z) = (0 < z)"
haftmann@25919
   506
by (insert zless_nat_conj [of 0], auto)
haftmann@25919
   507
haftmann@25919
   508
lemma nat_add_distrib:
haftmann@54223
   509
  "0 \<le> z \<Longrightarrow> 0 \<le> z' \<Longrightarrow> nat (z + z') = nat z + nat z'"
huffman@48045
   510
  by transfer clarsimp
haftmann@25919
   511
haftmann@54223
   512
lemma nat_diff_distrib':
haftmann@54223
   513
  "0 \<le> x \<Longrightarrow> 0 \<le> y \<Longrightarrow> nat (x - y) = nat x - nat y"
haftmann@54223
   514
  by transfer clarsimp
lp15@60162
   515
haftmann@25919
   516
lemma nat_diff_distrib:
haftmann@54223
   517
  "0 \<le> z' \<Longrightarrow> z' \<le> z \<Longrightarrow> nat (z - z') = nat z - nat z'"
haftmann@54223
   518
  by (rule nat_diff_distrib') auto
haftmann@25919
   519
huffman@44709
   520
lemma nat_zminus_int [simp]: "nat (- int n) = 0"
huffman@48045
   521
  by transfer simp
haftmann@25919
   522
haftmann@53065
   523
lemma le_nat_iff:
haftmann@53065
   524
  "k \<ge> 0 \<Longrightarrow> n \<le> nat k \<longleftrightarrow> int n \<le> k"
haftmann@53065
   525
  by transfer auto
lp15@60162
   526
huffman@44709
   527
lemma zless_nat_eq_int_zless: "(m < nat z) = (int m < z)"
huffman@48045
   528
  by transfer (clarsimp simp add: less_diff_conv)
haftmann@25919
   529
haftmann@25919
   530
context ring_1
haftmann@25919
   531
begin
haftmann@25919
   532
lp15@61609
   533
lemma of_nat_nat [simp]: "0 \<le> z \<Longrightarrow> of_nat (nat z) = of_int z"
huffman@48066
   534
  by transfer (clarsimp simp add: of_nat_diff)
haftmann@25919
   535
haftmann@25919
   536
end
haftmann@25919
   537
lp15@60162
   538
lemma diff_nat_numeral [simp]:
haftmann@54249
   539
  "(numeral v :: nat) - numeral v' = nat (numeral v - numeral v')"
haftmann@54249
   540
  by (simp only: nat_diff_distrib' zero_le_numeral nat_numeral)
haftmann@54249
   541
haftmann@54249
   542
wenzelm@60758
   543
text \<open>For termination proofs:\<close>
krauss@29779
   544
lemma measure_function_int[measure_function]: "is_measure (nat o abs)" ..
krauss@29779
   545
haftmann@25919
   546
wenzelm@60758
   547
subsection\<open>Lemmas about the Function @{term of_nat} and Orderings\<close>
haftmann@25919
   548
wenzelm@61076
   549
lemma negative_zless_0: "- (int (Suc n)) < (0 :: int)"
haftmann@25919
   550
by (simp add: order_less_le del: of_nat_Suc)
haftmann@25919
   551
huffman@44709
   552
lemma negative_zless [iff]: "- (int (Suc n)) < int m"
haftmann@25919
   553
by (rule negative_zless_0 [THEN order_less_le_trans], simp)
haftmann@25919
   554
huffman@44709
   555
lemma negative_zle_0: "- int n \<le> 0"
haftmann@25919
   556
by (simp add: minus_le_iff)
haftmann@25919
   557
huffman@44709
   558
lemma negative_zle [iff]: "- int n \<le> int m"
haftmann@25919
   559
by (rule order_trans [OF negative_zle_0 of_nat_0_le_iff])
haftmann@25919
   560
huffman@44709
   561
lemma not_zle_0_negative [simp]: "~ (0 \<le> - (int (Suc n)))"
haftmann@25919
   562
by (subst le_minus_iff, simp del: of_nat_Suc)
haftmann@25919
   563
huffman@44709
   564
lemma int_zle_neg: "(int n \<le> - int m) = (n = 0 & m = 0)"
huffman@48045
   565
  by transfer simp
haftmann@25919
   566
huffman@44709
   567
lemma not_int_zless_negative [simp]: "~ (int n < - int m)"
haftmann@25919
   568
by (simp add: linorder_not_less)
haftmann@25919
   569
huffman@44709
   570
lemma negative_eq_positive [simp]: "(- int n = of_nat m) = (n = 0 & m = 0)"
haftmann@25919
   571
by (force simp add: order_eq_iff [of "- of_nat n"] int_zle_neg)
haftmann@25919
   572
haftmann@62348
   573
lemma zle_iff_zadd:
haftmann@62348
   574
  "w \<le> z \<longleftrightarrow> (\<exists>n. z = w + int n)" (is "?P \<longleftrightarrow> ?Q")
haftmann@62348
   575
proof
haftmann@62348
   576
  assume ?Q
haftmann@62348
   577
  then show ?P by auto
haftmann@62348
   578
next
haftmann@62348
   579
  assume ?P
haftmann@62348
   580
  then have "0 \<le> z - w" by simp
haftmann@62348
   581
  then obtain n where "z - w = int n"
haftmann@62348
   582
    using zero_le_imp_eq_int [of "z - w"] by blast
haftmann@62348
   583
  then have "z = w + int n"
haftmann@62348
   584
    by simp
haftmann@62348
   585
  then show ?Q ..
haftmann@25919
   586
qed
haftmann@25919
   587
huffman@44709
   588
lemma zadd_int_left: "int m + (int n + z) = int (m + n) + z"
haftmann@25919
   589
by simp
haftmann@25919
   590
wenzelm@60758
   591
text\<open>This version is proved for all ordered rings, not just integers!
wenzelm@61799
   592
      It is proved here because attribute \<open>arith_split\<close> is not available
wenzelm@61799
   593
      in theory \<open>Rings\<close>.
wenzelm@61799
   594
      But is it really better than just rewriting with \<open>abs_if\<close>?\<close>
blanchet@54147
   595
lemma abs_split [arith_split, no_atp]:
wenzelm@61944
   596
     "P \<bar>a::'a::linordered_idom\<bar> = ((0 \<le> a --> P a) & (a < 0 --> P(-a)))"
haftmann@25919
   597
by (force dest: order_less_le_trans simp add: abs_if linorder_not_less)
haftmann@25919
   598
huffman@44709
   599
lemma negD: "x < 0 \<Longrightarrow> \<exists>n. x = - (int (Suc n))"
huffman@48045
   600
apply transfer
huffman@48045
   601
apply clarsimp
huffman@48045
   602
apply (rule_tac x="b - Suc a" in exI, arith)
haftmann@25919
   603
done
haftmann@25919
   604
wenzelm@60758
   605
subsection \<open>Cases and induction\<close>
haftmann@25919
   606
wenzelm@60758
   607
text\<open>Now we replace the case analysis rule by a more conventional one:
wenzelm@60758
   608
whether an integer is negative or not.\<close>
haftmann@25919
   609
wenzelm@60758
   610
text\<open>This version is symmetric in the two subgoals.\<close>
lp15@59613
   611
theorem int_cases2 [case_names nonneg nonpos, cases type: int]:
lp15@59613
   612
  "\<lbrakk>!! n. z = int n \<Longrightarrow> P;  !! n. z = - (int n) \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
lp15@59613
   613
apply (cases "z < 0")
lp15@59613
   614
apply (auto simp add: linorder_not_less dest!: negD nat_0_le [THEN sym])
lp15@59613
   615
done
lp15@59613
   616
wenzelm@60758
   617
text\<open>This is the default, with a negative case.\<close>
wenzelm@42676
   618
theorem int_cases [case_names nonneg neg, cases type: int]:
lp15@59613
   619
  "[|!! n. z = int n ==> P;  !! n. z = - (int (Suc n)) ==> P |] ==> P"
wenzelm@42676
   620
apply (cases "z < 0")
wenzelm@42676
   621
apply (blast dest!: negD)
haftmann@25919
   622
apply (simp add: linorder_not_less del: of_nat_Suc)
haftmann@25919
   623
apply auto
haftmann@25919
   624
apply (blast dest: nat_0_le [THEN sym])
haftmann@25919
   625
done
haftmann@25919
   626
haftmann@60868
   627
lemma int_cases3 [case_names zero pos neg]:
haftmann@60868
   628
  fixes k :: int
haftmann@60868
   629
  assumes "k = 0 \<Longrightarrow> P" and "\<And>n. k = int n \<Longrightarrow> n > 0 \<Longrightarrow> P"
paulson@61204
   630
    and "\<And>n. k = - int n \<Longrightarrow> n > 0 \<Longrightarrow> P"
haftmann@60868
   631
  shows "P"
haftmann@60868
   632
proof (cases k "0::int" rule: linorder_cases)
haftmann@60868
   633
  case equal with assms(1) show P by simp
haftmann@60868
   634
next
haftmann@60868
   635
  case greater
haftmann@60868
   636
  then have "nat k > 0" by simp
haftmann@60868
   637
  moreover from this have "k = int (nat k)" by auto
haftmann@60868
   638
  ultimately show P using assms(2) by blast
haftmann@60868
   639
next
haftmann@60868
   640
  case less
haftmann@60868
   641
  then have "nat (- k) > 0" by simp
haftmann@60868
   642
  moreover from this have "k = - int (nat (- k))" by auto
haftmann@60868
   643
  ultimately show P using assms(3) by blast
haftmann@60868
   644
qed
haftmann@60868
   645
wenzelm@42676
   646
theorem int_of_nat_induct [case_names nonneg neg, induct type: int]:
huffman@44709
   647
     "[|!! n. P (int n);  !!n. P (- (int (Suc n))) |] ==> P z"
wenzelm@42676
   648
  by (cases z) auto
haftmann@25919
   649
huffman@47207
   650
lemma nonneg_int_cases:
huffman@47207
   651
  assumes "0 \<le> k" obtains n where "k = int n"
haftmann@54489
   652
  using assms by (rule nonneg_eq_int)
huffman@47207
   653
huffman@47108
   654
lemma Let_numeral [simp]: "Let (numeral v) f = f (numeral v)"
wenzelm@61799
   655
  \<comment> \<open>Unfold all \<open>let\<close>s involving constants\<close>
wenzelm@61799
   656
  by (fact Let_numeral) \<comment> \<open>FIXME drop\<close>
haftmann@37767
   657
haftmann@54489
   658
lemma Let_neg_numeral [simp]: "Let (- numeral v) f = f (- numeral v)"
wenzelm@61799
   659
  \<comment> \<open>Unfold all \<open>let\<close>s involving constants\<close>
wenzelm@61799
   660
  by (fact Let_neg_numeral) \<comment> \<open>FIXME drop\<close>
haftmann@25919
   661
wenzelm@61799
   662
text \<open>Unfold \<open>min\<close> and \<open>max\<close> on numerals.\<close>
huffman@28958
   663
huffman@47108
   664
lemmas max_number_of [simp] =
huffman@47108
   665
  max_def [of "numeral u" "numeral v"]
haftmann@54489
   666
  max_def [of "numeral u" "- numeral v"]
haftmann@54489
   667
  max_def [of "- numeral u" "numeral v"]
haftmann@54489
   668
  max_def [of "- numeral u" "- numeral v"] for u v
huffman@28958
   669
huffman@47108
   670
lemmas min_number_of [simp] =
huffman@47108
   671
  min_def [of "numeral u" "numeral v"]
haftmann@54489
   672
  min_def [of "numeral u" "- numeral v"]
haftmann@54489
   673
  min_def [of "- numeral u" "numeral v"]
haftmann@54489
   674
  min_def [of "- numeral u" "- numeral v"] for u v
huffman@26075
   675
haftmann@25919
   676
wenzelm@60758
   677
subsubsection \<open>Binary comparisons\<close>
huffman@28958
   678
wenzelm@60758
   679
text \<open>Preliminaries\<close>
huffman@28958
   680
lp15@60162
   681
lemma le_imp_0_less:
huffman@28958
   682
  assumes le: "0 \<le> z"
huffman@28958
   683
  shows "(0::int) < 1 + z"
huffman@28958
   684
proof -
huffman@28958
   685
  have "0 \<le> z" by fact
huffman@47108
   686
  also have "... < z + 1" by (rule less_add_one)
haftmann@57514
   687
  also have "... = 1 + z" by (simp add: ac_simps)
huffman@28958
   688
  finally show "0 < 1 + z" .
huffman@28958
   689
qed
huffman@28958
   690
huffman@28958
   691
lemma odd_less_0_iff:
huffman@28958
   692
  "(1 + z + z < 0) = (z < (0::int))"
wenzelm@42676
   693
proof (cases z)
huffman@28958
   694
  case (nonneg n)
haftmann@57512
   695
  thus ?thesis by (simp add: linorder_not_less add.assoc add_increasing
lp15@60162
   696
                             le_imp_0_less [THEN order_less_imp_le])
huffman@28958
   697
next
huffman@28958
   698
  case (neg n)
huffman@30079
   699
  thus ?thesis by (simp del: of_nat_Suc of_nat_add of_nat_1
huffman@30079
   700
    add: algebra_simps of_nat_1 [where 'a=int, symmetric] of_nat_add [symmetric])
huffman@28958
   701
qed
huffman@28958
   702
wenzelm@60758
   703
subsubsection \<open>Comparisons, for Ordered Rings\<close>
haftmann@25919
   704
haftmann@25919
   705
lemmas double_eq_0_iff = double_zero
haftmann@25919
   706
haftmann@25919
   707
lemma odd_nonzero:
haftmann@33296
   708
  "1 + z + z \<noteq> (0::int)"
wenzelm@42676
   709
proof (cases z)
haftmann@25919
   710
  case (nonneg n)
lp15@60162
   711
  have le: "0 \<le> z+z" by (simp add: nonneg add_increasing)
haftmann@25919
   712
  thus ?thesis using  le_imp_0_less [OF le]
lp15@60162
   713
    by (auto simp add: add.assoc)
haftmann@25919
   714
next
haftmann@25919
   715
  case (neg n)
haftmann@25919
   716
  show ?thesis
haftmann@25919
   717
  proof
haftmann@25919
   718
    assume eq: "1 + z + z = 0"
huffman@44709
   719
    have "(0::int) < 1 + (int n + int n)"
lp15@60162
   720
      by (simp add: le_imp_0_less add_increasing)
lp15@60162
   721
    also have "... = - (1 + z + z)"
lp15@60162
   722
      by (simp add: neg add.assoc [symmetric])
lp15@60162
   723
    also have "... = 0" by (simp add: eq)
haftmann@25919
   724
    finally have "0<0" ..
haftmann@25919
   725
    thus False by blast
haftmann@25919
   726
  qed
haftmann@25919
   727
qed
haftmann@25919
   728
haftmann@30652
   729
wenzelm@60758
   730
subsection \<open>The Set of Integers\<close>
haftmann@25919
   731
haftmann@25919
   732
context ring_1
haftmann@25919
   733
begin
haftmann@25919
   734
wenzelm@61070
   735
definition Ints :: "'a set"  ("\<int>")
wenzelm@61070
   736
  where "\<int> = range of_int"
haftmann@25919
   737
huffman@35634
   738
lemma Ints_of_int [simp]: "of_int z \<in> \<int>"
huffman@35634
   739
  by (simp add: Ints_def)
huffman@35634
   740
huffman@35634
   741
lemma Ints_of_nat [simp]: "of_nat n \<in> \<int>"
huffman@45533
   742
  using Ints_of_int [of "of_nat n"] by simp
huffman@35634
   743
haftmann@25919
   744
lemma Ints_0 [simp]: "0 \<in> \<int>"
huffman@45533
   745
  using Ints_of_int [of "0"] by simp
haftmann@25919
   746
haftmann@25919
   747
lemma Ints_1 [simp]: "1 \<in> \<int>"
huffman@45533
   748
  using Ints_of_int [of "1"] by simp
haftmann@25919
   749
eberlm@61552
   750
lemma Ints_numeral [simp]: "numeral n \<in> \<int>"
eberlm@61552
   751
  by (subst of_nat_numeral [symmetric], rule Ints_of_nat)
eberlm@61552
   752
haftmann@25919
   753
lemma Ints_add [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a + b \<in> \<int>"
haftmann@25919
   754
apply (auto simp add: Ints_def)
haftmann@25919
   755
apply (rule range_eqI)
haftmann@25919
   756
apply (rule of_int_add [symmetric])
haftmann@25919
   757
done
haftmann@25919
   758
haftmann@25919
   759
lemma Ints_minus [simp]: "a \<in> \<int> \<Longrightarrow> -a \<in> \<int>"
haftmann@25919
   760
apply (auto simp add: Ints_def)
haftmann@25919
   761
apply (rule range_eqI)
haftmann@25919
   762
apply (rule of_int_minus [symmetric])
haftmann@25919
   763
done
haftmann@25919
   764
huffman@35634
   765
lemma Ints_diff [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a - b \<in> \<int>"
huffman@35634
   766
apply (auto simp add: Ints_def)
huffman@35634
   767
apply (rule range_eqI)
huffman@35634
   768
apply (rule of_int_diff [symmetric])
huffman@35634
   769
done
huffman@35634
   770
haftmann@25919
   771
lemma Ints_mult [simp]: "a \<in> \<int> \<Longrightarrow> b \<in> \<int> \<Longrightarrow> a * b \<in> \<int>"
haftmann@25919
   772
apply (auto simp add: Ints_def)
haftmann@25919
   773
apply (rule range_eqI)
haftmann@25919
   774
apply (rule of_int_mult [symmetric])
haftmann@25919
   775
done
haftmann@25919
   776
huffman@35634
   777
lemma Ints_power [simp]: "a \<in> \<int> \<Longrightarrow> a ^ n \<in> \<int>"
huffman@35634
   778
by (induct n) simp_all
huffman@35634
   779
haftmann@25919
   780
lemma Ints_cases [cases set: Ints]:
haftmann@25919
   781
  assumes "q \<in> \<int>"
haftmann@25919
   782
  obtains (of_int) z where "q = of_int z"
haftmann@25919
   783
  unfolding Ints_def
haftmann@25919
   784
proof -
wenzelm@60758
   785
  from \<open>q \<in> \<int>\<close> have "q \<in> range of_int" unfolding Ints_def .
haftmann@25919
   786
  then obtain z where "q = of_int z" ..
haftmann@25919
   787
  then show thesis ..
haftmann@25919
   788
qed
haftmann@25919
   789
haftmann@25919
   790
lemma Ints_induct [case_names of_int, induct set: Ints]:
haftmann@25919
   791
  "q \<in> \<int> \<Longrightarrow> (\<And>z. P (of_int z)) \<Longrightarrow> P q"
haftmann@25919
   792
  by (rule Ints_cases) auto
haftmann@25919
   793
eberlm@61524
   794
lemma Nats_subset_Ints: "\<nat> \<subseteq> \<int>"
eberlm@61524
   795
  unfolding Nats_def Ints_def
eberlm@61524
   796
  by (rule subsetI, elim imageE, hypsubst, subst of_int_of_nat_eq[symmetric], rule imageI) simp_all
eberlm@61524
   797
eberlm@61524
   798
lemma Nats_altdef1: "\<nat> = {of_int n |n. n \<ge> 0}"
eberlm@61524
   799
proof (intro subsetI equalityI)
eberlm@61524
   800
  fix x :: 'a assume "x \<in> {of_int n |n. n \<ge> 0}"
eberlm@61524
   801
  then obtain n where "x = of_int n" "n \<ge> 0" by (auto elim!: Ints_cases)
eberlm@61524
   802
  hence "x = of_nat (nat n)" by (subst of_nat_nat) simp_all
eberlm@61524
   803
  thus "x \<in> \<nat>" by simp
eberlm@61524
   804
next
eberlm@61524
   805
  fix x :: 'a assume "x \<in> \<nat>"
eberlm@61524
   806
  then obtain n where "x = of_nat n" by (auto elim!: Nats_cases)
eberlm@61524
   807
  hence "x = of_int (int n)" by simp
eberlm@61524
   808
  also have "int n \<ge> 0" by simp
eberlm@61524
   809
  hence "of_int (int n) \<in> {of_int n |n. n \<ge> 0}" by blast
eberlm@61524
   810
  finally show "x \<in> {of_int n |n. n \<ge> 0}" .
eberlm@61524
   811
qed
eberlm@61524
   812
haftmann@25919
   813
end
haftmann@25919
   814
eberlm@61524
   815
lemma (in linordered_idom) Nats_altdef2: "\<nat> = {n \<in> \<int>. n \<ge> 0}"
eberlm@61524
   816
proof (intro subsetI equalityI)
eberlm@61524
   817
  fix x :: 'a assume "x \<in> {n \<in> \<int>. n \<ge> 0}"
eberlm@61524
   818
  then obtain n where "x = of_int n" "n \<ge> 0" by (auto elim!: Ints_cases)
eberlm@61524
   819
  hence "x = of_nat (nat n)" by (subst of_nat_nat) simp_all
eberlm@61524
   820
  thus "x \<in> \<nat>" by simp
eberlm@61524
   821
qed (auto elim!: Nats_cases)
eberlm@61524
   822
eberlm@61524
   823
wenzelm@60758
   824
text \<open>The premise involving @{term Ints} prevents @{term "a = 1/2"}.\<close>
haftmann@25919
   825
haftmann@25919
   826
lemma Ints_double_eq_0_iff:
wenzelm@61070
   827
  assumes in_Ints: "a \<in> \<int>"
haftmann@25919
   828
  shows "(a + a = 0) = (a = (0::'a::ring_char_0))"
haftmann@25919
   829
proof -
haftmann@25919
   830
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   831
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   832
  show ?thesis
haftmann@25919
   833
  proof
haftmann@25919
   834
    assume "a = 0"
haftmann@25919
   835
    thus "a + a = 0" by simp
haftmann@25919
   836
  next
haftmann@25919
   837
    assume eq: "a + a = 0"
haftmann@25919
   838
    hence "of_int (z + z) = (of_int 0 :: 'a)" by (simp add: a)
haftmann@25919
   839
    hence "z + z = 0" by (simp only: of_int_eq_iff)
haftmann@25919
   840
    hence "z = 0" by (simp only: double_eq_0_iff)
haftmann@25919
   841
    thus "a = 0" by (simp add: a)
haftmann@25919
   842
  qed
haftmann@25919
   843
qed
haftmann@25919
   844
haftmann@25919
   845
lemma Ints_odd_nonzero:
wenzelm@61070
   846
  assumes in_Ints: "a \<in> \<int>"
haftmann@25919
   847
  shows "1 + a + a \<noteq> (0::'a::ring_char_0)"
haftmann@25919
   848
proof -
haftmann@25919
   849
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   850
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   851
  show ?thesis
haftmann@25919
   852
  proof
haftmann@25919
   853
    assume eq: "1 + a + a = 0"
haftmann@25919
   854
    hence "of_int (1 + z + z) = (of_int 0 :: 'a)" by (simp add: a)
haftmann@25919
   855
    hence "1 + z + z = 0" by (simp only: of_int_eq_iff)
haftmann@25919
   856
    with odd_nonzero show False by blast
haftmann@25919
   857
  qed
lp15@60162
   858
qed
haftmann@25919
   859
wenzelm@61070
   860
lemma Nats_numeral [simp]: "numeral w \<in> \<nat>"
huffman@47108
   861
  using of_nat_in_Nats [of "numeral w"] by simp
huffman@35634
   862
lp15@60162
   863
lemma Ints_odd_less_0:
wenzelm@61070
   864
  assumes in_Ints: "a \<in> \<int>"
haftmann@35028
   865
  shows "(1 + a + a < 0) = (a < (0::'a::linordered_idom))"
haftmann@25919
   866
proof -
haftmann@25919
   867
  from in_Ints have "a \<in> range of_int" unfolding Ints_def [symmetric] .
haftmann@25919
   868
  then obtain z where a: "a = of_int z" ..
haftmann@25919
   869
  hence "((1::'a) + a + a < 0) = (of_int (1 + z + z) < (of_int 0 :: 'a))"
haftmann@25919
   870
    by (simp add: a)
huffman@45532
   871
  also have "... = (z < 0)" by (simp only: of_int_less_iff odd_less_0_iff)
haftmann@25919
   872
  also have "... = (a < 0)" by (simp add: a)
haftmann@25919
   873
  finally show ?thesis .
haftmann@25919
   874
qed
haftmann@25919
   875
haftmann@25919
   876
wenzelm@60758
   877
subsection \<open>@{term setsum} and @{term setprod}\<close>
haftmann@25919
   878
lp15@61649
   879
lemma of_nat_setsum [simp]: "of_nat (setsum f A) = (\<Sum>x\<in>A. of_nat(f x))"
haftmann@25919
   880
  apply (cases "finite A")
haftmann@25919
   881
  apply (erule finite_induct, auto)
haftmann@25919
   882
  done
haftmann@25919
   883
lp15@61649
   884
lemma of_int_setsum [simp]: "of_int (setsum f A) = (\<Sum>x\<in>A. of_int(f x))"
haftmann@25919
   885
  apply (cases "finite A")
haftmann@25919
   886
  apply (erule finite_induct, auto)
haftmann@25919
   887
  done
haftmann@25919
   888
lp15@61649
   889
lemma of_nat_setprod [simp]: "of_nat (setprod f A) = (\<Prod>x\<in>A. of_nat(f x))"
haftmann@25919
   890
  apply (cases "finite A")
haftmann@25919
   891
  apply (erule finite_induct, auto simp add: of_nat_mult)
haftmann@25919
   892
  done
haftmann@25919
   893
lp15@61649
   894
lemma of_int_setprod [simp]: "of_int (setprod f A) = (\<Prod>x\<in>A. of_int(f x))"
haftmann@25919
   895
  apply (cases "finite A")
haftmann@25919
   896
  apply (erule finite_induct, auto)
haftmann@25919
   897
  done
haftmann@25919
   898
haftmann@25919
   899
lemmas int_setsum = of_nat_setsum [where 'a=int]
haftmann@25919
   900
lemmas int_setprod = of_nat_setprod [where 'a=int]
haftmann@25919
   901
haftmann@25919
   902
wenzelm@60758
   903
text \<open>Legacy theorems\<close>
haftmann@25919
   904
haftmann@25919
   905
lemmas zle_int = of_nat_le_iff [where 'a=int]
haftmann@25919
   906
lemmas int_int_eq = of_nat_eq_iff [where 'a=int]
haftmann@25919
   907
wenzelm@60758
   908
subsection \<open>Setting up simplification procedures\<close>
huffman@30802
   909
haftmann@54249
   910
lemmas of_int_simps =
haftmann@54249
   911
  of_int_0 of_int_1 of_int_add of_int_mult
haftmann@54249
   912
wenzelm@48891
   913
ML_file "Tools/int_arith.ML"
wenzelm@60758
   914
declaration \<open>K Int_Arith.setup\<close>
haftmann@25919
   915
huffman@47108
   916
simproc_setup fast_arith ("(m::'a::linordered_idom) < n" |
wenzelm@61144
   917
  "(m::'a::linordered_idom) \<le> n" |
huffman@47108
   918
  "(m::'a::linordered_idom) = n") =
wenzelm@61144
   919
  \<open>K Lin_Arith.simproc\<close>
wenzelm@43595
   920
haftmann@25919
   921
wenzelm@60758
   922
subsection\<open>More Inequality Reasoning\<close>
haftmann@25919
   923
haftmann@25919
   924
lemma zless_add1_eq: "(w < z + (1::int)) = (w<z | w=z)"
haftmann@25919
   925
by arith
haftmann@25919
   926
haftmann@25919
   927
lemma add1_zle_eq: "(w + (1::int) \<le> z) = (w<z)"
haftmann@25919
   928
by arith
haftmann@25919
   929
haftmann@25919
   930
lemma zle_diff1_eq [simp]: "(w \<le> z - (1::int)) = (w<z)"
haftmann@25919
   931
by arith
haftmann@25919
   932
haftmann@25919
   933
lemma zle_add1_eq_le [simp]: "(w < z + (1::int)) = (w\<le>z)"
haftmann@25919
   934
by arith
haftmann@25919
   935
haftmann@25919
   936
lemma int_one_le_iff_zero_less: "((1::int) \<le> z) = (0 < z)"
haftmann@25919
   937
by arith
haftmann@25919
   938
haftmann@25919
   939
wenzelm@60758
   940
subsection\<open>The functions @{term nat} and @{term int}\<close>
haftmann@25919
   941
wenzelm@60758
   942
text\<open>Simplify the term @{term "w + - z"}\<close>
haftmann@25919
   943
haftmann@25919
   944
lemma one_less_nat_eq [simp]: "(Suc 0 < nat z) = (1 < z)"
lp15@60162
   945
  using zless_nat_conj [of 1 z] by auto
haftmann@25919
   946
wenzelm@60758
   947
text\<open>This simplifies expressions of the form @{term "int n = z"} where
wenzelm@60758
   948
      z is an integer literal.\<close>
huffman@47108
   949
lemmas int_eq_iff_numeral [simp] = int_eq_iff [of _ "numeral v"] for v
haftmann@25919
   950
haftmann@25919
   951
lemma split_nat [arith_split]:
huffman@44709
   952
  "P(nat(i::int)) = ((\<forall>n. i = int n \<longrightarrow> P n) & (i < 0 \<longrightarrow> P 0))"
haftmann@25919
   953
  (is "?P = (?L & ?R)")
haftmann@25919
   954
proof (cases "i < 0")
haftmann@25919
   955
  case True thus ?thesis by auto
haftmann@25919
   956
next
haftmann@25919
   957
  case False
haftmann@25919
   958
  have "?P = ?L"
haftmann@25919
   959
  proof
haftmann@25919
   960
    assume ?P thus ?L using False by clarsimp
haftmann@25919
   961
  next
haftmann@25919
   962
    assume ?L thus ?P using False by simp
haftmann@25919
   963
  qed
haftmann@25919
   964
  with False show ?thesis by simp
haftmann@25919
   965
qed
haftmann@25919
   966
hoelzl@59000
   967
lemma nat_abs_int_diff: "nat \<bar>int a - int b\<bar> = (if a \<le> b then b - a else a - b)"
hoelzl@59000
   968
  by auto
hoelzl@59000
   969
hoelzl@59000
   970
lemma nat_int_add: "nat (int a + int b) = a + b"
hoelzl@59000
   971
  by auto
hoelzl@59000
   972
haftmann@25919
   973
context ring_1
haftmann@25919
   974
begin
haftmann@25919
   975
blanchet@33056
   976
lemma of_int_of_nat [nitpick_simp]:
haftmann@25919
   977
  "of_int k = (if k < 0 then - of_nat (nat (- k)) else of_nat (nat k))"
haftmann@25919
   978
proof (cases "k < 0")
haftmann@25919
   979
  case True then have "0 \<le> - k" by simp
haftmann@25919
   980
  then have "of_nat (nat (- k)) = of_int (- k)" by (rule of_nat_nat)
haftmann@25919
   981
  with True show ?thesis by simp
haftmann@25919
   982
next
haftmann@25919
   983
  case False then show ?thesis by (simp add: not_less of_nat_nat)
haftmann@25919
   984
qed
haftmann@25919
   985
haftmann@25919
   986
end
haftmann@25919
   987
haftmann@25919
   988
lemma nat_mult_distrib:
haftmann@25919
   989
  fixes z z' :: int
haftmann@25919
   990
  assumes "0 \<le> z"
haftmann@25919
   991
  shows "nat (z * z') = nat z * nat z'"
haftmann@25919
   992
proof (cases "0 \<le> z'")
haftmann@25919
   993
  case False with assms have "z * z' \<le> 0"
haftmann@25919
   994
    by (simp add: not_le mult_le_0_iff)
haftmann@25919
   995
  then have "nat (z * z') = 0" by simp
haftmann@25919
   996
  moreover from False have "nat z' = 0" by simp
haftmann@25919
   997
  ultimately show ?thesis by simp
haftmann@25919
   998
next
haftmann@25919
   999
  case True with assms have ge_0: "z * z' \<ge> 0" by (simp add: zero_le_mult_iff)
haftmann@25919
  1000
  show ?thesis
haftmann@25919
  1001
    by (rule injD [of "of_nat :: nat \<Rightarrow> int", OF inj_of_nat])
haftmann@25919
  1002
      (simp only: of_nat_mult of_nat_nat [OF True]
haftmann@25919
  1003
         of_nat_nat [OF assms] of_nat_nat [OF ge_0], simp)
haftmann@25919
  1004
qed
haftmann@25919
  1005
haftmann@25919
  1006
lemma nat_mult_distrib_neg: "z \<le> (0::int) ==> nat(z*z') = nat(-z) * nat(-z')"
haftmann@25919
  1007
apply (rule trans)
haftmann@25919
  1008
apply (rule_tac [2] nat_mult_distrib, auto)
haftmann@25919
  1009
done
haftmann@25919
  1010
wenzelm@61944
  1011
lemma nat_abs_mult_distrib: "nat \<bar>w * z\<bar> = nat \<bar>w\<bar> * nat \<bar>z\<bar>"
haftmann@25919
  1012
apply (cases "z=0 | w=0")
lp15@60162
  1013
apply (auto simp add: abs_if nat_mult_distrib [symmetric]
haftmann@25919
  1014
                      nat_mult_distrib_neg [symmetric] mult_less_0_iff)
haftmann@25919
  1015
done
haftmann@25919
  1016
haftmann@60570
  1017
lemma int_in_range_abs [simp]:
haftmann@60570
  1018
  "int n \<in> range abs"
haftmann@60570
  1019
proof (rule range_eqI)
haftmann@60570
  1020
  show "int n = \<bar>int n\<bar>"
haftmann@60570
  1021
    by simp
haftmann@60570
  1022
qed
haftmann@60570
  1023
haftmann@60570
  1024
lemma range_abs_Nats [simp]:
haftmann@60570
  1025
  "range abs = (\<nat> :: int set)"
haftmann@60570
  1026
proof -
haftmann@60570
  1027
  have "\<bar>k\<bar> \<in> \<nat>" for k :: int
haftmann@60570
  1028
    by (cases k) simp_all
haftmann@60570
  1029
  moreover have "k \<in> range abs" if "k \<in> \<nat>" for k :: int
haftmann@60570
  1030
    using that by induct simp
haftmann@60570
  1031
  ultimately show ?thesis by blast
paulson@61204
  1032
qed
haftmann@60570
  1033
huffman@47207
  1034
lemma Suc_nat_eq_nat_zadd1: "(0::int) <= z ==> Suc (nat z) = nat (1 + z)"
huffman@47207
  1035
apply (rule sym)
huffman@47207
  1036
apply (simp add: nat_eq_iff)
huffman@47207
  1037
done
huffman@47207
  1038
huffman@47207
  1039
lemma diff_nat_eq_if:
lp15@60162
  1040
     "nat z - nat z' =
lp15@60162
  1041
        (if z' < 0 then nat z
lp15@60162
  1042
         else let d = z-z' in
huffman@47207
  1043
              if d < 0 then 0 else nat d)"
huffman@47207
  1044
by (simp add: Let_def nat_diff_distrib [symmetric])
huffman@47207
  1045
huffman@47207
  1046
lemma nat_numeral_diff_1 [simp]:
huffman@47207
  1047
  "numeral v - (1::nat) = nat (numeral v - 1)"
huffman@47207
  1048
  using diff_nat_numeral [of v Num.One] by simp
huffman@47207
  1049
haftmann@25919
  1050
haftmann@25919
  1051
subsection "Induction principles for int"
haftmann@25919
  1052
wenzelm@60758
  1053
text\<open>Well-founded segments of the integers\<close>
haftmann@25919
  1054
haftmann@25919
  1055
definition
haftmann@25919
  1056
  int_ge_less_than  ::  "int => (int * int) set"
haftmann@25919
  1057
where
haftmann@25919
  1058
  "int_ge_less_than d = {(z',z). d \<le> z' & z' < z}"
haftmann@25919
  1059
haftmann@25919
  1060
theorem wf_int_ge_less_than: "wf (int_ge_less_than d)"
haftmann@25919
  1061
proof -
haftmann@25919
  1062
  have "int_ge_less_than d \<subseteq> measure (%z. nat (z-d))"
haftmann@25919
  1063
    by (auto simp add: int_ge_less_than_def)
lp15@60162
  1064
  thus ?thesis
lp15@60162
  1065
    by (rule wf_subset [OF wf_measure])
haftmann@25919
  1066
qed
haftmann@25919
  1067
wenzelm@60758
  1068
text\<open>This variant looks odd, but is typical of the relations suggested
wenzelm@60758
  1069
by RankFinder.\<close>
haftmann@25919
  1070
haftmann@25919
  1071
definition
haftmann@25919
  1072
  int_ge_less_than2 ::  "int => (int * int) set"
haftmann@25919
  1073
where
haftmann@25919
  1074
  "int_ge_less_than2 d = {(z',z). d \<le> z & z' < z}"
haftmann@25919
  1075
haftmann@25919
  1076
theorem wf_int_ge_less_than2: "wf (int_ge_less_than2 d)"
haftmann@25919
  1077
proof -
lp15@60162
  1078
  have "int_ge_less_than2 d \<subseteq> measure (%z. nat (1+z-d))"
haftmann@25919
  1079
    by (auto simp add: int_ge_less_than2_def)
lp15@60162
  1080
  thus ?thesis
lp15@60162
  1081
    by (rule wf_subset [OF wf_measure])
haftmann@25919
  1082
qed
haftmann@25919
  1083
haftmann@25919
  1084
(* `set:int': dummy construction *)
haftmann@25919
  1085
theorem int_ge_induct [case_names base step, induct set: int]:
haftmann@25919
  1086
  fixes i :: int
haftmann@25919
  1087
  assumes ge: "k \<le> i" and
haftmann@25919
  1088
    base: "P k" and
haftmann@25919
  1089
    step: "\<And>i. k \<le> i \<Longrightarrow> P i \<Longrightarrow> P (i + 1)"
haftmann@25919
  1090
  shows "P i"
haftmann@25919
  1091
proof -
wenzelm@42676
  1092
  { fix n
wenzelm@42676
  1093
    have "\<And>i::int. n = nat (i - k) \<Longrightarrow> k \<le> i \<Longrightarrow> P i"
haftmann@25919
  1094
    proof (induct n)
haftmann@25919
  1095
      case 0
haftmann@25919
  1096
      hence "i = k" by arith
haftmann@25919
  1097
      thus "P i" using base by simp
haftmann@25919
  1098
    next
haftmann@25919
  1099
      case (Suc n)
haftmann@25919
  1100
      then have "n = nat((i - 1) - k)" by arith
haftmann@25919
  1101
      moreover
haftmann@25919
  1102
      have ki1: "k \<le> i - 1" using Suc.prems by arith
haftmann@25919
  1103
      ultimately
wenzelm@42676
  1104
      have "P (i - 1)" by (rule Suc.hyps)
wenzelm@42676
  1105
      from step [OF ki1 this] show ?case by simp
haftmann@25919
  1106
    qed
haftmann@25919
  1107
  }
haftmann@25919
  1108
  with ge show ?thesis by fast
haftmann@25919
  1109
qed
haftmann@25919
  1110
haftmann@25928
  1111
(* `set:int': dummy construction *)
haftmann@25928
  1112
theorem int_gr_induct [case_names base step, induct set: int]:
haftmann@25919
  1113
  assumes gr: "k < (i::int)" and
haftmann@25919
  1114
        base: "P(k+1)" and
haftmann@25919
  1115
        step: "\<And>i. \<lbrakk>k < i; P i\<rbrakk> \<Longrightarrow> P(i+1)"
haftmann@25919
  1116
  shows "P i"
haftmann@25919
  1117
apply(rule int_ge_induct[of "k + 1"])
haftmann@25919
  1118
  using gr apply arith
haftmann@25919
  1119
 apply(rule base)
haftmann@25919
  1120
apply (rule step, simp+)
haftmann@25919
  1121
done
haftmann@25919
  1122
wenzelm@42676
  1123
theorem int_le_induct [consumes 1, case_names base step]:
haftmann@25919
  1124
  assumes le: "i \<le> (k::int)" and
haftmann@25919
  1125
        base: "P(k)" and
haftmann@25919
  1126
        step: "\<And>i. \<lbrakk>i \<le> k; P i\<rbrakk> \<Longrightarrow> P(i - 1)"
haftmann@25919
  1127
  shows "P i"
haftmann@25919
  1128
proof -
wenzelm@42676
  1129
  { fix n
wenzelm@42676
  1130
    have "\<And>i::int. n = nat(k-i) \<Longrightarrow> i \<le> k \<Longrightarrow> P i"
haftmann@25919
  1131
    proof (induct n)
haftmann@25919
  1132
      case 0
haftmann@25919
  1133
      hence "i = k" by arith
haftmann@25919
  1134
      thus "P i" using base by simp
haftmann@25919
  1135
    next
haftmann@25919
  1136
      case (Suc n)
wenzelm@42676
  1137
      hence "n = nat (k - (i + 1))" by arith
haftmann@25919
  1138
      moreover
haftmann@25919
  1139
      have ki1: "i + 1 \<le> k" using Suc.prems by arith
haftmann@25919
  1140
      ultimately
wenzelm@42676
  1141
      have "P (i + 1)" by(rule Suc.hyps)
haftmann@25919
  1142
      from step[OF ki1 this] show ?case by simp
haftmann@25919
  1143
    qed
haftmann@25919
  1144
  }
haftmann@25919
  1145
  with le show ?thesis by fast
haftmann@25919
  1146
qed
haftmann@25919
  1147
wenzelm@42676
  1148
theorem int_less_induct [consumes 1, case_names base step]:
haftmann@25919
  1149
  assumes less: "(i::int) < k" and
haftmann@25919
  1150
        base: "P(k - 1)" and
haftmann@25919
  1151
        step: "\<And>i. \<lbrakk>i < k; P i\<rbrakk> \<Longrightarrow> P(i - 1)"
haftmann@25919
  1152
  shows "P i"
haftmann@25919
  1153
apply(rule int_le_induct[of _ "k - 1"])
haftmann@25919
  1154
  using less apply arith
haftmann@25919
  1155
 apply(rule base)
haftmann@25919
  1156
apply (rule step, simp+)
haftmann@25919
  1157
done
haftmann@25919
  1158
haftmann@36811
  1159
theorem int_induct [case_names base step1 step2]:
haftmann@36801
  1160
  fixes k :: int
haftmann@36801
  1161
  assumes base: "P k"
haftmann@36801
  1162
    and step1: "\<And>i. k \<le> i \<Longrightarrow> P i \<Longrightarrow> P (i + 1)"
haftmann@36801
  1163
    and step2: "\<And>i. k \<ge> i \<Longrightarrow> P i \<Longrightarrow> P (i - 1)"
haftmann@36801
  1164
  shows "P i"
haftmann@36801
  1165
proof -
haftmann@36801
  1166
  have "i \<le> k \<or> i \<ge> k" by arith
wenzelm@42676
  1167
  then show ?thesis
wenzelm@42676
  1168
  proof
wenzelm@42676
  1169
    assume "i \<ge> k"
wenzelm@42676
  1170
    then show ?thesis using base
haftmann@36801
  1171
      by (rule int_ge_induct) (fact step1)
haftmann@36801
  1172
  next
wenzelm@42676
  1173
    assume "i \<le> k"
wenzelm@42676
  1174
    then show ?thesis using base
haftmann@36801
  1175
      by (rule int_le_induct) (fact step2)
haftmann@36801
  1176
  qed
haftmann@36801
  1177
qed
haftmann@36801
  1178
wenzelm@60758
  1179
subsection\<open>Intermediate value theorems\<close>
haftmann@25919
  1180
haftmann@25919
  1181
lemma int_val_lemma:
wenzelm@61944
  1182
     "(\<forall>i<n::nat. \<bar>f(i+1) - f i\<bar> \<le> 1) -->
haftmann@25919
  1183
      f 0 \<le> k --> k \<le> f n --> (\<exists>i \<le> n. f i = (k::int))"
huffman@30079
  1184
unfolding One_nat_def
wenzelm@42676
  1185
apply (induct n)
wenzelm@42676
  1186
apply simp
haftmann@25919
  1187
apply (intro strip)
haftmann@25919
  1188
apply (erule impE, simp)
haftmann@25919
  1189
apply (erule_tac x = n in allE, simp)
huffman@30079
  1190
apply (case_tac "k = f (Suc n)")
haftmann@27106
  1191
apply force
haftmann@25919
  1192
apply (erule impE)
nipkow@62390
  1193
 apply (simp add: abs_if split add: if_split_asm)
haftmann@25919
  1194
apply (blast intro: le_SucI)
haftmann@25919
  1195
done
haftmann@25919
  1196
haftmann@25919
  1197
lemmas nat0_intermed_int_val = int_val_lemma [rule_format (no_asm)]
haftmann@25919
  1198
haftmann@25919
  1199
lemma nat_intermed_int_val:
wenzelm@61944
  1200
     "[| \<forall>i. m \<le> i & i < n --> \<bar>f(i + 1::nat) - f i\<bar> \<le> 1; m < n;
haftmann@25919
  1201
         f m \<le> k; k \<le> f n |] ==> ? i. m \<le> i & i \<le> n & f i = (k::int)"
lp15@60162
  1202
apply (cut_tac n = "n-m" and f = "%i. f (i+m) " and k = k
haftmann@25919
  1203
       in int_val_lemma)
huffman@30079
  1204
unfolding One_nat_def
haftmann@25919
  1205
apply simp
haftmann@25919
  1206
apply (erule exE)
haftmann@25919
  1207
apply (rule_tac x = "i+m" in exI, arith)
haftmann@25919
  1208
done
haftmann@25919
  1209
haftmann@25919
  1210
wenzelm@60758
  1211
subsection\<open>Products and 1, by T. M. Rasmussen\<close>
haftmann@25919
  1212
paulson@34055
  1213
lemma abs_zmult_eq_1:
paulson@34055
  1214
  assumes mn: "\<bar>m * n\<bar> = 1"
paulson@34055
  1215
  shows "\<bar>m\<bar> = (1::int)"
paulson@34055
  1216
proof -
paulson@34055
  1217
  have 0: "m \<noteq> 0 & n \<noteq> 0" using mn
paulson@34055
  1218
    by auto
paulson@34055
  1219
  have "~ (2 \<le> \<bar>m\<bar>)"
paulson@34055
  1220
  proof
paulson@34055
  1221
    assume "2 \<le> \<bar>m\<bar>"
paulson@34055
  1222
    hence "2*\<bar>n\<bar> \<le> \<bar>m\<bar>*\<bar>n\<bar>"
lp15@60162
  1223
      by (simp add: mult_mono 0)
lp15@60162
  1224
    also have "... = \<bar>m*n\<bar>"
paulson@34055
  1225
      by (simp add: abs_mult)
paulson@34055
  1226
    also have "... = 1"
paulson@34055
  1227
      by (simp add: mn)
paulson@34055
  1228
    finally have "2*\<bar>n\<bar> \<le> 1" .
paulson@34055
  1229
    thus "False" using 0
huffman@47108
  1230
      by arith
paulson@34055
  1231
  qed
paulson@34055
  1232
  thus ?thesis using 0
paulson@34055
  1233
    by auto
paulson@34055
  1234
qed
haftmann@25919
  1235
haftmann@25919
  1236
lemma pos_zmult_eq_1_iff_lemma: "(m * n = 1) ==> m = (1::int) | m = -1"
haftmann@25919
  1237
by (insert abs_zmult_eq_1 [of m n], arith)
haftmann@25919
  1238
boehmes@35815
  1239
lemma pos_zmult_eq_1_iff:
boehmes@35815
  1240
  assumes "0 < (m::int)" shows "(m * n = 1) = (m = 1 & n = 1)"
boehmes@35815
  1241
proof -
boehmes@35815
  1242
  from assms have "m * n = 1 ==> m = 1" by (auto dest: pos_zmult_eq_1_iff_lemma)
boehmes@35815
  1243
  thus ?thesis by (auto dest: pos_zmult_eq_1_iff_lemma)
boehmes@35815
  1244
qed
haftmann@25919
  1245
haftmann@25919
  1246
lemma zmult_eq_1_iff: "(m*n = (1::int)) = ((m = 1 & n = 1) | (m = -1 & n = -1))"
lp15@60162
  1247
apply (rule iffI)
haftmann@25919
  1248
 apply (frule pos_zmult_eq_1_iff_lemma)
lp15@60162
  1249
 apply (simp add: mult.commute [of m])
lp15@60162
  1250
 apply (frule pos_zmult_eq_1_iff_lemma, auto)
haftmann@25919
  1251
done
haftmann@25919
  1252
haftmann@33296
  1253
lemma infinite_UNIV_int: "\<not> finite (UNIV::int set)"
haftmann@25919
  1254
proof
haftmann@33296
  1255
  assume "finite (UNIV::int set)"
wenzelm@61076
  1256
  moreover have "inj (\<lambda>i::int. 2 * i)"
haftmann@33296
  1257
    by (rule injI) simp
wenzelm@61076
  1258
  ultimately have "surj (\<lambda>i::int. 2 * i)"
haftmann@33296
  1259
    by (rule finite_UNIV_inj_surj)
haftmann@33296
  1260
  then obtain i :: int where "1 = 2 * i" by (rule surjE)
haftmann@33296
  1261
  then show False by (simp add: pos_zmult_eq_1_iff)
haftmann@25919
  1262
qed
haftmann@25919
  1263
haftmann@25919
  1264
wenzelm@60758
  1265
subsection \<open>Further theorems on numerals\<close>
haftmann@30652
  1266
wenzelm@60758
  1267
subsubsection\<open>Special Simplification for Constants\<close>
haftmann@30652
  1268
wenzelm@60758
  1269
text\<open>These distributive laws move literals inside sums and differences.\<close>
haftmann@30652
  1270
webertj@49962
  1271
lemmas distrib_right_numeral [simp] = distrib_right [of _ _ "numeral v"] for v
webertj@49962
  1272
lemmas distrib_left_numeral [simp] = distrib_left [of "numeral v"] for v
huffman@47108
  1273
lemmas left_diff_distrib_numeral [simp] = left_diff_distrib [of _ _ "numeral v"] for v
huffman@47108
  1274
lemmas right_diff_distrib_numeral [simp] = right_diff_distrib [of "numeral v"] for v
haftmann@30652
  1275
wenzelm@60758
  1276
text\<open>These are actually for fields, like real: but where else to put them?\<close>
haftmann@30652
  1277
huffman@47108
  1278
lemmas zero_less_divide_iff_numeral [simp, no_atp] = zero_less_divide_iff [of "numeral w"] for w
huffman@47108
  1279
lemmas divide_less_0_iff_numeral [simp, no_atp] = divide_less_0_iff [of "numeral w"] for w
huffman@47108
  1280
lemmas zero_le_divide_iff_numeral [simp, no_atp] = zero_le_divide_iff [of "numeral w"] for w
huffman@47108
  1281
lemmas divide_le_0_iff_numeral [simp, no_atp] = divide_le_0_iff [of "numeral w"] for w
haftmann@30652
  1282
haftmann@30652
  1283
wenzelm@61799
  1284
text \<open>Replaces \<open>inverse #nn\<close> by \<open>1/#nn\<close>.  It looks
wenzelm@60758
  1285
  strange, but then other simprocs simplify the quotient.\<close>
haftmann@30652
  1286
huffman@47108
  1287
lemmas inverse_eq_divide_numeral [simp] =
huffman@47108
  1288
  inverse_eq_divide [of "numeral w"] for w
huffman@47108
  1289
huffman@47108
  1290
lemmas inverse_eq_divide_neg_numeral [simp] =
haftmann@54489
  1291
  inverse_eq_divide [of "- numeral w"] for w
haftmann@30652
  1292
wenzelm@60758
  1293
text \<open>These laws simplify inequalities, moving unary minus from a term
wenzelm@60758
  1294
into the literal.\<close>
haftmann@30652
  1295
haftmann@54489
  1296
lemmas equation_minus_iff_numeral [no_atp] =
haftmann@54489
  1297
  equation_minus_iff [of "numeral v"] for v
huffman@47108
  1298
haftmann@54489
  1299
lemmas minus_equation_iff_numeral [no_atp] =
haftmann@54489
  1300
  minus_equation_iff [of _ "numeral v"] for v
huffman@47108
  1301
haftmann@54489
  1302
lemmas le_minus_iff_numeral [no_atp] =
haftmann@54489
  1303
  le_minus_iff [of "numeral v"] for v
haftmann@30652
  1304
haftmann@54489
  1305
lemmas minus_le_iff_numeral [no_atp] =
haftmann@54489
  1306
  minus_le_iff [of _ "numeral v"] for v
haftmann@30652
  1307
haftmann@54489
  1308
lemmas less_minus_iff_numeral [no_atp] =
haftmann@54489
  1309
  less_minus_iff [of "numeral v"] for v
haftmann@30652
  1310
haftmann@54489
  1311
lemmas minus_less_iff_numeral [no_atp] =
haftmann@54489
  1312
  minus_less_iff [of _ "numeral v"] for v
haftmann@30652
  1313
wenzelm@61799
  1314
\<comment> \<open>FIXME maybe simproc\<close>
haftmann@30652
  1315
haftmann@30652
  1316
wenzelm@61799
  1317
text \<open>Cancellation of constant factors in comparisons (\<open><\<close> and \<open>\<le>\<close>)\<close>
haftmann@30652
  1318
huffman@47108
  1319
lemmas mult_less_cancel_left_numeral [simp, no_atp] = mult_less_cancel_left [of "numeral v"] for v
huffman@47108
  1320
lemmas mult_less_cancel_right_numeral [simp, no_atp] = mult_less_cancel_right [of _ "numeral v"] for v
huffman@47108
  1321
lemmas mult_le_cancel_left_numeral [simp, no_atp] = mult_le_cancel_left [of "numeral v"] for v
huffman@47108
  1322
lemmas mult_le_cancel_right_numeral [simp, no_atp] = mult_le_cancel_right [of _ "numeral v"] for v
haftmann@30652
  1323
haftmann@30652
  1324
wenzelm@61799
  1325
text \<open>Multiplying out constant divisors in comparisons (\<open><\<close>, \<open>\<le>\<close> and \<open>=\<close>)\<close>
haftmann@30652
  1326
lp15@61738
  1327
named_theorems divide_const_simps "simplification rules to simplify comparisons involving constant divisors"
lp15@61738
  1328
lp15@61738
  1329
lemmas le_divide_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1330
  pos_le_divide_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1331
  neg_le_divide_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1332
lp15@61738
  1333
lemmas divide_le_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1334
  pos_divide_le_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1335
  neg_divide_le_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1336
lp15@61738
  1337
lemmas less_divide_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1338
  pos_less_divide_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1339
  neg_less_divide_eq [of "- numeral w", OF neg_numeral_less_zero] for w
haftmann@30652
  1340
lp15@61738
  1341
lemmas divide_less_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1342
  pos_divide_less_eq [of "numeral w", OF zero_less_numeral]
haftmann@54489
  1343
  neg_divide_less_eq [of "- numeral w", OF neg_numeral_less_zero] for w
huffman@47108
  1344
lp15@61738
  1345
lemmas eq_divide_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1346
  eq_divide_eq [of _ _ "numeral w"]
haftmann@54489
  1347
  eq_divide_eq [of _ _ "- numeral w"] for w
huffman@47108
  1348
lp15@61738
  1349
lemmas divide_eq_eq_numeral1 [simp,divide_const_simps] =
huffman@47108
  1350
  divide_eq_eq [of _ "numeral w"]
haftmann@54489
  1351
  divide_eq_eq [of _ "- numeral w"] for w
haftmann@54489
  1352
haftmann@30652
  1353
wenzelm@60758
  1354
subsubsection\<open>Optional Simplification Rules Involving Constants\<close>
haftmann@30652
  1355
wenzelm@60758
  1356
text\<open>Simplify quotients that are compared with a literal constant.\<close>
haftmann@30652
  1357
lp15@61738
  1358
lemmas le_divide_eq_numeral [divide_const_simps] =
huffman@47108
  1359
  le_divide_eq [of "numeral w"]
haftmann@54489
  1360
  le_divide_eq [of "- numeral w"] for w
huffman@47108
  1361
lp15@61738
  1362
lemmas divide_le_eq_numeral [divide_const_simps] =
huffman@47108
  1363
  divide_le_eq [of _ _ "numeral w"]
haftmann@54489
  1364
  divide_le_eq [of _ _ "- numeral w"] for w
huffman@47108
  1365
lp15@61738
  1366
lemmas less_divide_eq_numeral [divide_const_simps] =
huffman@47108
  1367
  less_divide_eq [of "numeral w"]
haftmann@54489
  1368
  less_divide_eq [of "- numeral w"] for w
huffman@47108
  1369
lp15@61738
  1370
lemmas divide_less_eq_numeral [divide_const_simps] =
huffman@47108
  1371
  divide_less_eq [of _ _ "numeral w"]
haftmann@54489
  1372
  divide_less_eq [of _ _ "- numeral w"] for w
huffman@47108
  1373
lp15@61738
  1374
lemmas eq_divide_eq_numeral [divide_const_simps] =
huffman@47108
  1375
  eq_divide_eq [of "numeral w"]
haftmann@54489
  1376
  eq_divide_eq [of "- numeral w"] for w
huffman@47108
  1377
lp15@61738
  1378
lemmas divide_eq_eq_numeral [divide_const_simps] =
huffman@47108
  1379
  divide_eq_eq [of _ _ "numeral w"]
haftmann@54489
  1380
  divide_eq_eq [of _ _ "- numeral w"] for w
haftmann@30652
  1381
haftmann@30652
  1382
wenzelm@60758
  1383
text\<open>Not good as automatic simprules because they cause case splits.\<close>
lp15@61738
  1384
lemmas [divide_const_simps] = le_divide_eq_1 divide_le_eq_1 less_divide_eq_1 divide_less_eq_1 
haftmann@30652
  1385
haftmann@30652
  1386
wenzelm@60758
  1387
subsection \<open>The divides relation\<close>
haftmann@33320
  1388
nipkow@33657
  1389
lemma zdvd_antisym_nonneg:
nipkow@33657
  1390
    "0 <= m ==> 0 <= n ==> m dvd n ==> n dvd m ==> m = (n::int)"
haftmann@33320
  1391
  apply (simp add: dvd_def, auto)
haftmann@57512
  1392
  apply (auto simp add: mult.assoc zero_le_mult_iff zmult_eq_1_iff)
haftmann@33320
  1393
  done
haftmann@33320
  1394
lp15@60162
  1395
lemma zdvd_antisym_abs: assumes "(a::int) dvd b" and "b dvd a"
haftmann@33320
  1396
  shows "\<bar>a\<bar> = \<bar>b\<bar>"
nipkow@33657
  1397
proof cases
nipkow@33657
  1398
  assume "a = 0" with assms show ?thesis by simp
nipkow@33657
  1399
next
nipkow@33657
  1400
  assume "a \<noteq> 0"
wenzelm@60758
  1401
  from \<open>a dvd b\<close> obtain k where k:"b = a*k" unfolding dvd_def by blast
wenzelm@60758
  1402
  from \<open>b dvd a\<close> obtain k' where k':"a = b*k'" unfolding dvd_def by blast
haftmann@33320
  1403
  from k k' have "a = a*k*k'" by simp
haftmann@33320
  1404
  with mult_cancel_left1[where c="a" and b="k*k'"]
wenzelm@60758
  1405
  have kk':"k*k' = 1" using \<open>a\<noteq>0\<close> by (simp add: mult.assoc)
haftmann@33320
  1406
  hence "k = 1 \<and> k' = 1 \<or> k = -1 \<and> k' = -1" by (simp add: zmult_eq_1_iff)
haftmann@33320
  1407
  thus ?thesis using k k' by auto
haftmann@33320
  1408
qed
haftmann@33320
  1409
haftmann@33320
  1410
lemma zdvd_zdiffD: "k dvd m - n ==> k dvd n ==> k dvd (m::int)"
lp15@60162
  1411
  using dvd_add_right_iff [of k "- n" m] by simp
haftmann@33320
  1412
haftmann@33320
  1413
lemma zdvd_reduce: "(k dvd n + k * m) = (k dvd (n::int))"
haftmann@58649
  1414
  using dvd_add_times_triv_right_iff [of k n m] by (simp add: ac_simps)
haftmann@33320
  1415
haftmann@33320
  1416
lemma dvd_imp_le_int:
haftmann@33320
  1417
  fixes d i :: int
haftmann@33320
  1418
  assumes "i \<noteq> 0" and "d dvd i"
haftmann@33320
  1419
  shows "\<bar>d\<bar> \<le> \<bar>i\<bar>"
haftmann@33320
  1420
proof -
wenzelm@60758
  1421
  from \<open>d dvd i\<close> obtain k where "i = d * k" ..
wenzelm@60758
  1422
  with \<open>i \<noteq> 0\<close> have "k \<noteq> 0" by auto
haftmann@33320
  1423
  then have "1 \<le> \<bar>k\<bar>" and "0 \<le> \<bar>d\<bar>" by auto
haftmann@33320
  1424
  then have "\<bar>d\<bar> * 1 \<le> \<bar>d\<bar> * \<bar>k\<bar>" by (rule mult_left_mono)
wenzelm@60758
  1425
  with \<open>i = d * k\<close> show ?thesis by (simp add: abs_mult)
haftmann@33320
  1426
qed
haftmann@33320
  1427
haftmann@33320
  1428
lemma zdvd_not_zless:
haftmann@33320
  1429
  fixes m n :: int
haftmann@33320
  1430
  assumes "0 < m" and "m < n"
haftmann@33320
  1431
  shows "\<not> n dvd m"
haftmann@33320
  1432
proof
haftmann@33320
  1433
  from assms have "0 < n" by auto
haftmann@33320
  1434
  assume "n dvd m" then obtain k where k: "m = n * k" ..
wenzelm@60758
  1435
  with \<open>0 < m\<close> have "0 < n * k" by auto
wenzelm@60758
  1436
  with \<open>0 < n\<close> have "0 < k" by (simp add: zero_less_mult_iff)
wenzelm@60758
  1437
  with k \<open>0 < n\<close> \<open>m < n\<close> have "n * k < n * 1" by simp
wenzelm@60758
  1438
  with \<open>0 < n\<close> \<open>0 < k\<close> show False unfolding mult_less_cancel_left by auto
haftmann@33320
  1439
qed
haftmann@33320
  1440
haftmann@33320
  1441
lemma zdvd_mult_cancel: assumes d:"k * m dvd k * n" and kz:"k \<noteq> (0::int)"
haftmann@33320
  1442
  shows "m dvd n"
haftmann@33320
  1443
proof-
haftmann@33320
  1444
  from d obtain h where h: "k*n = k*m * h" unfolding dvd_def by blast
haftmann@33320
  1445
  {assume "n \<noteq> m*h" hence "k* n \<noteq> k* (m*h)" using kz by simp
haftmann@57512
  1446
    with h have False by (simp add: mult.assoc)}
haftmann@33320
  1447
  hence "n = m * h" by blast
haftmann@33320
  1448
  thus ?thesis by simp
haftmann@33320
  1449
qed
haftmann@33320
  1450
haftmann@33320
  1451
theorem zdvd_int: "(x dvd y) = (int x dvd int y)"
haftmann@33320
  1452
proof -
haftmann@33320
  1453
  have "\<And>k. int y = int x * k \<Longrightarrow> x dvd y"
haftmann@33320
  1454
  proof -
haftmann@33320
  1455
    fix k
haftmann@33320
  1456
    assume A: "int y = int x * k"
wenzelm@42676
  1457
    then show "x dvd y"
wenzelm@42676
  1458
    proof (cases k)
wenzelm@42676
  1459
      case (nonneg n)
lp15@61649
  1460
      with A have "y = x * n" by (simp del: of_nat_mult add: of_nat_mult [symmetric])
haftmann@33320
  1461
      then show ?thesis ..
haftmann@33320
  1462
    next
wenzelm@42676
  1463
      case (neg n)
wenzelm@42676
  1464
      with A have "int y = int x * (- int (Suc n))" by simp
haftmann@33320
  1465
      also have "\<dots> = - (int x * int (Suc n))" by (simp only: mult_minus_right)
haftmann@33320
  1466
      also have "\<dots> = - int (x * Suc n)" by (simp only: of_nat_mult [symmetric])
haftmann@33320
  1467
      finally have "- int (x * Suc n) = int y" ..
haftmann@33320
  1468
      then show ?thesis by (simp only: negative_eq_positive) auto
haftmann@33320
  1469
    qed
haftmann@33320
  1470
  qed
haftmann@33320
  1471
  then show ?thesis by (auto elim!: dvdE simp only: dvd_triv_left of_nat_mult)
haftmann@33320
  1472
qed
haftmann@33320
  1473
wenzelm@42676
  1474
lemma zdvd1_eq[simp]: "(x::int) dvd 1 = (\<bar>x\<bar> = 1)"
haftmann@33320
  1475
proof
haftmann@33320
  1476
  assume d: "x dvd 1" hence "int (nat \<bar>x\<bar>) dvd int (nat 1)" by simp
haftmann@33320
  1477
  hence "nat \<bar>x\<bar> dvd 1" by (simp add: zdvd_int)
haftmann@33320
  1478
  hence "nat \<bar>x\<bar> = 1"  by simp
wenzelm@42676
  1479
  thus "\<bar>x\<bar> = 1" by (cases "x < 0") auto
haftmann@33320
  1480
next
haftmann@33320
  1481
  assume "\<bar>x\<bar>=1"
haftmann@33320
  1482
  then have "x = 1 \<or> x = -1" by auto
haftmann@33320
  1483
  then show "x dvd 1" by (auto intro: dvdI)
haftmann@33320
  1484
qed
haftmann@33320
  1485
lp15@60162
  1486
lemma zdvd_mult_cancel1:
haftmann@33320
  1487
  assumes mp:"m \<noteq>(0::int)" shows "(m * n dvd m) = (\<bar>n\<bar> = 1)"
haftmann@33320
  1488
proof
lp15@60162
  1489
  assume n1: "\<bar>n\<bar> = 1" thus "m * n dvd m"
wenzelm@42676
  1490
    by (cases "n >0") (auto simp add: minus_equation_iff)
haftmann@33320
  1491
next
haftmann@33320
  1492
  assume H: "m * n dvd m" hence H2: "m * n dvd m * 1" by simp
haftmann@33320
  1493
  from zdvd_mult_cancel[OF H2 mp] show "\<bar>n\<bar> = 1" by (simp only: zdvd1_eq)
haftmann@33320
  1494
qed
haftmann@33320
  1495
wenzelm@61944
  1496
lemma int_dvd_iff: "(int m dvd z) = (m dvd nat \<bar>z\<bar>)"
haftmann@33320
  1497
  unfolding zdvd_int by (cases "z \<ge> 0") simp_all
haftmann@33320
  1498
wenzelm@61944
  1499
lemma dvd_int_iff: "(z dvd int m) = (nat \<bar>z\<bar> dvd m)"
haftmann@33320
  1500
  unfolding zdvd_int by (cases "z \<ge> 0") simp_all
haftmann@33320
  1501
haftmann@58650
  1502
lemma dvd_int_unfold_dvd_nat:
haftmann@58650
  1503
  "k dvd l \<longleftrightarrow> nat \<bar>k\<bar> dvd nat \<bar>l\<bar>"
haftmann@58650
  1504
  unfolding dvd_int_iff [symmetric] by simp
haftmann@58650
  1505
haftmann@33320
  1506
lemma nat_dvd_iff: "(nat z dvd m) = (if 0 \<le> z then (z dvd int m) else m = 0)"
haftmann@33320
  1507
  by (auto simp add: dvd_int_iff)
haftmann@33320
  1508
haftmann@33341
  1509
lemma eq_nat_nat_iff:
haftmann@33341
  1510
  "0 \<le> z \<Longrightarrow> 0 \<le> z' \<Longrightarrow> nat z = nat z' \<longleftrightarrow> z = z'"
haftmann@33341
  1511
  by (auto elim!: nonneg_eq_int)
haftmann@33341
  1512
haftmann@33341
  1513
lemma nat_power_eq:
haftmann@33341
  1514
  "0 \<le> z \<Longrightarrow> nat (z ^ n) = nat z ^ n"
haftmann@33341
  1515
  by (induct n) (simp_all add: nat_mult_distrib)
haftmann@33341
  1516
haftmann@33320
  1517
lemma zdvd_imp_le: "[| z dvd n; 0 < n |] ==> z \<le> (n::int)"
wenzelm@42676
  1518
  apply (cases n)
haftmann@33320
  1519
  apply (auto simp add: dvd_int_iff)
wenzelm@42676
  1520
  apply (cases z)
haftmann@33320
  1521
  apply (auto simp add: dvd_imp_le)
haftmann@33320
  1522
  done
haftmann@33320
  1523
haftmann@36749
  1524
lemma zdvd_period:
haftmann@36749
  1525
  fixes a d :: int
haftmann@36749
  1526
  assumes "a dvd d"
haftmann@36749
  1527
  shows "a dvd (x + t) \<longleftrightarrow> a dvd ((x + c * d) + t)"
haftmann@36749
  1528
proof -
haftmann@36749
  1529
  from assms obtain k where "d = a * k" by (rule dvdE)
wenzelm@42676
  1530
  show ?thesis
wenzelm@42676
  1531
  proof
haftmann@36749
  1532
    assume "a dvd (x + t)"
haftmann@36749
  1533
    then obtain l where "x + t = a * l" by (rule dvdE)
haftmann@36749
  1534
    then have "x = a * l - t" by simp
wenzelm@60758
  1535
    with \<open>d = a * k\<close> show "a dvd x + c * d + t" by simp
haftmann@36749
  1536
  next
haftmann@36749
  1537
    assume "a dvd x + c * d + t"
haftmann@36749
  1538
    then obtain l where "x + c * d + t = a * l" by (rule dvdE)
haftmann@36749
  1539
    then have "x = a * l - c * d - t" by simp
wenzelm@60758
  1540
    with \<open>d = a * k\<close> show "a dvd (x + t)" by simp
haftmann@36749
  1541
  qed
haftmann@36749
  1542
qed
haftmann@36749
  1543
haftmann@33320
  1544
wenzelm@60758
  1545
subsection \<open>Finiteness of intervals\<close>
bulwahn@46756
  1546
bulwahn@46756
  1547
lemma finite_interval_int1 [iff]: "finite {i :: int. a <= i & i <= b}"
bulwahn@46756
  1548
proof (cases "a <= b")
bulwahn@46756
  1549
  case True
bulwahn@46756
  1550
  from this show ?thesis
bulwahn@46756
  1551
  proof (induct b rule: int_ge_induct)
bulwahn@46756
  1552
    case base
bulwahn@46756
  1553
    have "{i. a <= i & i <= a} = {a}" by auto
bulwahn@46756
  1554
    from this show ?case by simp
bulwahn@46756
  1555
  next
bulwahn@46756
  1556
    case (step b)
bulwahn@46756
  1557
    from this have "{i. a <= i & i <= b + 1} = {i. a <= i & i <= b} \<union> {b + 1}" by auto
bulwahn@46756
  1558
    from this step show ?case by simp
bulwahn@46756
  1559
  qed
bulwahn@46756
  1560
next
bulwahn@46756
  1561
  case False from this show ?thesis
bulwahn@46756
  1562
    by (metis (lifting, no_types) Collect_empty_eq finite.emptyI order_trans)
bulwahn@46756
  1563
qed
bulwahn@46756
  1564
bulwahn@46756
  1565
lemma finite_interval_int2 [iff]: "finite {i :: int. a <= i & i < b}"
bulwahn@46756
  1566
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1567
bulwahn@46756
  1568
lemma finite_interval_int3 [iff]: "finite {i :: int. a < i & i <= b}"
bulwahn@46756
  1569
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1570
bulwahn@46756
  1571
lemma finite_interval_int4 [iff]: "finite {i :: int. a < i & i < b}"
bulwahn@46756
  1572
by (rule rev_finite_subset[OF finite_interval_int1[of "a" "b"]]) auto
bulwahn@46756
  1573
bulwahn@46756
  1574
wenzelm@60758
  1575
subsection \<open>Configuration of the code generator\<close>
haftmann@25919
  1576
wenzelm@60758
  1577
text \<open>Constructors\<close>
huffman@47108
  1578
huffman@47108
  1579
definition Pos :: "num \<Rightarrow> int" where
huffman@47108
  1580
  [simp, code_abbrev]: "Pos = numeral"
huffman@47108
  1581
huffman@47108
  1582
definition Neg :: "num \<Rightarrow> int" where
haftmann@54489
  1583
  [simp, code_abbrev]: "Neg n = - (Pos n)"
huffman@47108
  1584
huffman@47108
  1585
code_datatype "0::int" Pos Neg
huffman@47108
  1586
huffman@47108
  1587
wenzelm@60758
  1588
text \<open>Auxiliary operations\<close>
huffman@47108
  1589
huffman@47108
  1590
definition dup :: "int \<Rightarrow> int" where
huffman@47108
  1591
  [simp]: "dup k = k + k"
haftmann@26507
  1592
huffman@47108
  1593
lemma dup_code [code]:
huffman@47108
  1594
  "dup 0 = 0"
huffman@47108
  1595
  "dup (Pos n) = Pos (Num.Bit0 n)"
huffman@47108
  1596
  "dup (Neg n) = Neg (Num.Bit0 n)"
haftmann@54489
  1597
  unfolding Pos_def Neg_def
huffman@47108
  1598
  by (simp_all add: numeral_Bit0)
huffman@47108
  1599
huffman@47108
  1600
definition sub :: "num \<Rightarrow> num \<Rightarrow> int" where
huffman@47108
  1601
  [simp]: "sub m n = numeral m - numeral n"
haftmann@26507
  1602
huffman@47108
  1603
lemma sub_code [code]:
huffman@47108
  1604
  "sub Num.One Num.One = 0"
huffman@47108
  1605
  "sub (Num.Bit0 m) Num.One = Pos (Num.BitM m)"
huffman@47108
  1606
  "sub (Num.Bit1 m) Num.One = Pos (Num.Bit0 m)"
huffman@47108
  1607
  "sub Num.One (Num.Bit0 n) = Neg (Num.BitM n)"
huffman@47108
  1608
  "sub Num.One (Num.Bit1 n) = Neg (Num.Bit0 n)"
huffman@47108
  1609
  "sub (Num.Bit0 m) (Num.Bit0 n) = dup (sub m n)"
huffman@47108
  1610
  "sub (Num.Bit1 m) (Num.Bit1 n) = dup (sub m n)"
huffman@47108
  1611
  "sub (Num.Bit1 m) (Num.Bit0 n) = dup (sub m n) + 1"
huffman@47108
  1612
  "sub (Num.Bit0 m) (Num.Bit1 n) = dup (sub m n) - 1"
haftmann@54489
  1613
  apply (simp_all only: sub_def dup_def numeral.simps Pos_def Neg_def numeral_BitM)
haftmann@54230
  1614
  apply (simp_all only: algebra_simps minus_diff_eq)
haftmann@54230
  1615
  apply (simp_all only: add.commute [of _ "- (numeral n + numeral n)"])
haftmann@54230
  1616
  apply (simp_all only: minus_add add.assoc left_minus)
haftmann@54230
  1617
  done
huffman@47108
  1618
wenzelm@60758
  1619
text \<open>Implementations\<close>
huffman@47108
  1620
huffman@47108
  1621
lemma one_int_code [code, code_unfold]:
huffman@47108
  1622
  "1 = Pos Num.One"
huffman@47108
  1623
  by simp
huffman@47108
  1624
huffman@47108
  1625
lemma plus_int_code [code]:
huffman@47108
  1626
  "k + 0 = (k::int)"
huffman@47108
  1627
  "0 + l = (l::int)"
huffman@47108
  1628
  "Pos m + Pos n = Pos (m + n)"
huffman@47108
  1629
  "Pos m + Neg n = sub m n"
huffman@47108
  1630
  "Neg m + Pos n = sub n m"
huffman@47108
  1631
  "Neg m + Neg n = Neg (m + n)"
huffman@47108
  1632
  by simp_all
haftmann@26507
  1633
huffman@47108
  1634
lemma uminus_int_code [code]:
huffman@47108
  1635
  "uminus 0 = (0::int)"
huffman@47108
  1636
  "uminus (Pos m) = Neg m"
huffman@47108
  1637
  "uminus (Neg m) = Pos m"
huffman@47108
  1638
  by simp_all
huffman@47108
  1639
huffman@47108
  1640
lemma minus_int_code [code]:
huffman@47108
  1641
  "k - 0 = (k::int)"
huffman@47108
  1642
  "0 - l = uminus (l::int)"
huffman@47108
  1643
  "Pos m - Pos n = sub m n"
huffman@47108
  1644
  "Pos m - Neg n = Pos (m + n)"
huffman@47108
  1645
  "Neg m - Pos n = Neg (m + n)"
huffman@47108
  1646
  "Neg m - Neg n = sub n m"
huffman@47108
  1647
  by simp_all
huffman@47108
  1648
huffman@47108
  1649
lemma times_int_code [code]:
huffman@47108
  1650
  "k * 0 = (0::int)"
huffman@47108
  1651
  "0 * l = (0::int)"
huffman@47108
  1652
  "Pos m * Pos n = Pos (m * n)"
huffman@47108
  1653
  "Pos m * Neg n = Neg (m * n)"
huffman@47108
  1654
  "Neg m * Pos n = Neg (m * n)"
huffman@47108
  1655
  "Neg m * Neg n = Pos (m * n)"
huffman@47108
  1656
  by simp_all
haftmann@26507
  1657
haftmann@38857
  1658
instantiation int :: equal
haftmann@26507
  1659
begin
haftmann@26507
  1660
haftmann@37767
  1661
definition
huffman@47108
  1662
  "HOL.equal k l \<longleftrightarrow> k = (l::int)"
haftmann@38857
  1663
wenzelm@61169
  1664
instance
wenzelm@61169
  1665
  by standard (rule equal_int_def)
haftmann@26507
  1666
haftmann@26507
  1667
end
haftmann@26507
  1668
huffman@47108
  1669
lemma equal_int_code [code]:
huffman@47108
  1670
  "HOL.equal 0 (0::int) \<longleftrightarrow> True"
huffman@47108
  1671
  "HOL.equal 0 (Pos l) \<longleftrightarrow> False"
huffman@47108
  1672
  "HOL.equal 0 (Neg l) \<longleftrightarrow> False"
huffman@47108
  1673
  "HOL.equal (Pos k) 0 \<longleftrightarrow> False"
huffman@47108
  1674
  "HOL.equal (Pos k) (Pos l) \<longleftrightarrow> HOL.equal k l"
huffman@47108
  1675
  "HOL.equal (Pos k) (Neg l) \<longleftrightarrow> False"
huffman@47108
  1676
  "HOL.equal (Neg k) 0 \<longleftrightarrow> False"
huffman@47108
  1677
  "HOL.equal (Neg k) (Pos l) \<longleftrightarrow> False"
huffman@47108
  1678
  "HOL.equal (Neg k) (Neg l) \<longleftrightarrow> HOL.equal k l"
huffman@47108
  1679
  by (auto simp add: equal)
haftmann@26507
  1680
huffman@47108
  1681
lemma equal_int_refl [code nbe]:
haftmann@38857
  1682
  "HOL.equal (k::int) k \<longleftrightarrow> True"
huffman@47108
  1683
  by (fact equal_refl)
haftmann@26507
  1684
haftmann@28562
  1685
lemma less_eq_int_code [code]:
huffman@47108
  1686
  "0 \<le> (0::int) \<longleftrightarrow> True"
huffman@47108
  1687
  "0 \<le> Pos l \<longleftrightarrow> True"
huffman@47108
  1688
  "0 \<le> Neg l \<longleftrightarrow> False"
huffman@47108
  1689
  "Pos k \<le> 0 \<longleftrightarrow> False"
huffman@47108
  1690
  "Pos k \<le> Pos l \<longleftrightarrow> k \<le> l"
huffman@47108
  1691
  "Pos k \<le> Neg l \<longleftrightarrow> False"
huffman@47108
  1692
  "Neg k \<le> 0 \<longleftrightarrow> True"
huffman@47108
  1693
  "Neg k \<le> Pos l \<longleftrightarrow> True"
huffman@47108
  1694
  "Neg k \<le> Neg l \<longleftrightarrow> l \<le> k"
huffman@28958
  1695
  by simp_all
haftmann@26507
  1696
haftmann@28562
  1697
lemma less_int_code [code]:
huffman@47108
  1698
  "0 < (0::int) \<longleftrightarrow> False"
huffman@47108
  1699
  "0 < Pos l \<longleftrightarrow> True"
huffman@47108
  1700
  "0 < Neg l \<longleftrightarrow> False"
huffman@47108
  1701
  "Pos k < 0 \<longleftrightarrow> False"
huffman@47108
  1702
  "Pos k < Pos l \<longleftrightarrow> k < l"
huffman@47108
  1703
  "Pos k < Neg l \<longleftrightarrow> False"
huffman@47108
  1704
  "Neg k < 0 \<longleftrightarrow> True"
huffman@47108
  1705
  "Neg k < Pos l \<longleftrightarrow> True"
huffman@47108
  1706
  "Neg k < Neg l \<longleftrightarrow> l < k"
huffman@28958
  1707
  by simp_all
haftmann@25919
  1708
huffman@47108
  1709
lemma nat_code [code]:
huffman@47108
  1710
  "nat (Int.Neg k) = 0"
huffman@47108
  1711
  "nat 0 = 0"
huffman@47108
  1712
  "nat (Int.Pos k) = nat_of_num k"
haftmann@54489
  1713
  by (simp_all add: nat_of_num_numeral)
haftmann@25928
  1714
huffman@47108
  1715
lemma (in ring_1) of_int_code [code]:
haftmann@54489
  1716
  "of_int (Int.Neg k) = - numeral k"
huffman@47108
  1717
  "of_int 0 = 0"
huffman@47108
  1718
  "of_int (Int.Pos k) = numeral k"
huffman@47108
  1719
  by simp_all
haftmann@25919
  1720
huffman@47108
  1721
wenzelm@60758
  1722
text \<open>Serializer setup\<close>
haftmann@25919
  1723
haftmann@52435
  1724
code_identifier
haftmann@52435
  1725
  code_module Int \<rightharpoonup> (SML) Arith and (OCaml) Arith and (Haskell) Arith
haftmann@25919
  1726
haftmann@25919
  1727
quickcheck_params [default_type = int]
haftmann@25919
  1728
huffman@47108
  1729
hide_const (open) Pos Neg sub dup
haftmann@25919
  1730
haftmann@25919
  1731
wenzelm@61799
  1732
text \<open>De-register \<open>int\<close> as a quotient type:\<close>
huffman@48045
  1733
kuncar@53652
  1734
lifting_update int.lifting
kuncar@53652
  1735
lifting_forget int.lifting
huffman@48045
  1736
haftmann@25919
  1737
end