# HG changeset patch
# User haftmann
# Date 1193730354 -3600
# Node ID 022029099a83e5eaa562e7eabe173abb771617a5
# Parent  2673709fb8f770a9791909c1c5371ee984c6a575
continued localization

diff -r 2673709fb8f7 -r 022029099a83 src/HOL/Hyperreal/StarClasses.thy
--- a/src/HOL/Hyperreal/StarClasses.thy	Mon Oct 29 17:08:01 2007 +0100
+++ b/src/HOL/Hyperreal/StarClasses.thy	Tue Oct 30 08:45:54 2007 +0100
@@ -403,7 +403,7 @@
 done
 
 instance star :: (pordered_comm_semiring) pordered_comm_semiring
-by (intro_classes, transfer, rule mult_mono1_class.times_zero_less_eq_less.mult_mono)
+by (intro_classes, transfer, rule mult_mono1_class.times_zero_less_eq_less.mult_mono1)
 
 instance star :: (pordered_cancel_comm_semiring) pordered_cancel_comm_semiring ..
 
@@ -451,7 +451,7 @@
 subsection {* Number classes *}
 
 lemma star_of_nat_def [transfer_unfold]: "of_nat n = star_of (of_nat n)"
-by (induct_tac n, simp_all)
+by (induct n, simp_all)
 
 lemma Standard_of_nat [simp]: "of_nat n \<in> Standard"
 by (simp add: star_of_nat_def)
diff -r 2673709fb8f7 -r 022029099a83 src/HOL/IntArith.thy
--- a/src/HOL/IntArith.thy	Mon Oct 29 17:08:01 2007 +0100
+++ b/src/HOL/IntArith.thy	Tue Oct 30 08:45:54 2007 +0100
@@ -208,9 +208,20 @@
   with False show ?thesis by simp
 qed
 
-lemma of_int_of_nat: "of_int k = (if k < 0 then - of_nat (nat (- k))
-  else of_nat (nat k))"
-  by (auto simp add: of_nat_nat)
+context ring_1
+begin
+
+lemma of_int_of_nat:
+  "of_int k = (if k < 0 then - of_nat (nat (- k)) else of_nat (nat k))"
+proof (cases "k < 0")
+  case True then have "0 \<le> - k" by simp
+  then have "of_nat (nat (- k)) = of_int (- k)" by (rule of_nat_nat)
+  with True show ?thesis by simp
+next
+  case False then show ?thesis by (simp add: not_less of_nat_nat)
+qed
+
+end
 
 lemma nat_mult_distrib: "(0::int) \<le> z ==> nat (z*z') = nat z * nat z'"
 apply (cases "0 \<le> z'")
diff -r 2673709fb8f7 -r 022029099a83 src/HOL/IntDef.thy
--- a/src/HOL/IntDef.thy	Mon Oct 29 17:08:01 2007 +0100
+++ b/src/HOL/IntDef.thy	Tue Oct 30 08:45:54 2007 +0100
@@ -429,6 +429,8 @@
 context ring_1
 begin
 
+term of_nat
+
 definition
   of_int :: "int \<Rightarrow> 'a"
 where
@@ -518,10 +520,15 @@
     by (cases z) (simp add: of_int add minus int_def diff_minus)
 qed
 
+context ring_1
+begin
+
 lemma of_nat_nat: "0 \<le> z \<Longrightarrow> of_nat (nat z) = of_int z"
-by (cases z rule: eq_Abs_Integ)
+  by (cases z rule: eq_Abs_Integ)
    (simp add: nat le of_int Zero_int_def of_nat_diff)
 
+end
+
 
 subsection{*The Set of Integers*}
 
diff -r 2673709fb8f7 -r 022029099a83 src/HOL/OrderedGroup.thy
--- a/src/HOL/OrderedGroup.thy	Mon Oct 29 17:08:01 2007 +0100
+++ b/src/HOL/OrderedGroup.thy	Tue Oct 30 08:45:54 2007 +0100
@@ -535,8 +535,21 @@
 lemma le_iff_diff_le_0: "a \<le> b \<longleftrightarrow> a - b \<le> 0"
   by (simp add: compare_rls)
 
+lemmas group_simps =
+  add_ac
+  add_diff_eq diff_add_eq diff_diff_eq diff_diff_eq2
+  diff_eq_eq eq_diff_eq diff_minus [symmetric] uminus_add_conv_diff
+  diff_less_eq less_diff_eq diff_le_eq le_diff_eq
+
 end
 
+lemmas group_simps =
+  mult_ac
+  add_ac
+  add_diff_eq diff_add_eq diff_diff_eq diff_diff_eq2
+  diff_eq_eq eq_diff_eq diff_minus [symmetric] uminus_add_conv_diff
+  diff_less_eq less_diff_eq diff_le_eq le_diff_eq
+
 class ordered_ab_semigroup_add =
   linorder + pordered_ab_semigroup_add
 
@@ -565,6 +578,12 @@
   qed
 qed
 
+class ordered_ab_group_add =
+  linorder + pordered_ab_group_add
+
+subclass (in ordered_ab_group_add) ordered_cancel_ab_semigroup_add 
+  by unfold_locales
+
 -- {* FIXME localize the following *}
 
 lemma add_increasing:
@@ -752,6 +771,12 @@
     (simp add: le_infI)
 qed
 
+lemma neg_inf_eq_sup: "- inf a b = sup (-a) (-b)"
+  by (simp add: inf_eq_neg_sup)
+
+lemma neg_sup_eq_inf: "- sup a b = inf (-a) (-b)"
+  by (simp add: sup_eq_neg_inf)
+
 lemma add_eq_inf_sup: "a + b = sup a b + inf a b"
 proof -
   have "0 = - inf 0 (a-b) + inf (a-b) 0" by (simp add: inf_commute)
@@ -776,6 +801,21 @@
   pprt :: "'a \<Rightarrow> 'a" where
   "pprt x = sup x 0"
 
+lemma pprt_neg: "pprt (- x) = - nprt x"
+proof -
+  have "sup (- x) 0 = sup (- x) (- 0)" unfolding minus_zero ..
+  also have "\<dots> = - inf x 0" unfolding neg_inf_eq_sup ..
+  finally have "sup (- x) 0 = - inf x 0" .
+  then show ?thesis unfolding pprt_def nprt_def .
+qed
+
+lemma nprt_neg: "nprt (- x) = - pprt x"
+proof -
+  from pprt_neg have "pprt (- (- x)) = - nprt (- x)" .
+  then have "pprt x = - nprt (- x)" by simp
+  then show ?thesis by simp
+qed
+
 lemma prts: "a = pprt a + nprt a"
   by (simp add: pprt_def nprt_def add_eq_inf_sup[symmetric])
 
@@ -904,38 +944,67 @@
   ultimately show ?thesis by blast
 qed
 
+declare neg_inf_eq_sup [simp] neg_sup_eq_inf [simp]
+
+lemma le_minus_self_iff: "a \<le> - a \<longleftrightarrow> a \<le> 0"
+proof -
+  from add_le_cancel_left [of "uminus a" "plus a a" zero]
+  have "(a <= -a) = (a+a <= 0)" 
+    by (simp add: add_assoc[symmetric])
+  thus ?thesis by simp
+qed
+
+lemma minus_le_self_iff: "- a \<le> a \<longleftrightarrow> 0 \<le> a"
+proof -
+  from add_le_cancel_left [of "uminus a" zero "plus a a"]
+  have "(-a <= a) = (0 <= a+a)" 
+    by (simp add: add_assoc[symmetric])
+  thus ?thesis by simp
+qed
+
+lemma zero_le_iff_zero_nprt: "0 \<le> a \<longleftrightarrow> nprt a = 0"
+  by (simp add: le_iff_inf nprt_def inf_commute)
+
+lemma le_zero_iff_zero_pprt: "a \<le> 0 \<longleftrightarrow> pprt a = 0"
+  by (simp add: le_iff_sup pprt_def sup_commute)
+
+lemma le_zero_iff_pprt_id: "0 \<le> a \<longleftrightarrow> pprt a = a"
+  by (simp add: le_iff_sup pprt_def sup_commute)
+
+lemma zero_le_iff_nprt_id: "a \<le> 0 \<longleftrightarrow> nprt a = a"
+  by (simp add: le_iff_inf nprt_def inf_commute)
+
+lemma pprt_mono [simp, noatp]: "a \<le> b \<Longrightarrow> pprt a \<le> pprt b"
+  by (simp add: le_iff_sup pprt_def sup_ACI sup_assoc [symmetric, of a])
+
+lemma nprt_mono [simp, noatp]: "a \<le> b \<Longrightarrow> nprt a \<le> nprt b"
+  by (simp add: le_iff_inf nprt_def inf_ACI inf_assoc [symmetric, of a])
+
 end
 
 lemmas add_sup_inf_distribs = add_inf_distrib_right add_inf_distrib_left add_sup_distrib_right add_sup_distrib_left
 
-class lordered_ab_group_abs = lordered_ab_group + abs +
-  assumes abs_lattice: "\<bar>x\<bar> = sup x (- x)"
+
+class pordered_ab_group_add_abs = pordered_ab_group_add + abs +
+  assumes abs_ge_zero [simp]: "\<bar>a\<bar> \<ge> 0"
+    and abs_ge_self: "a \<le> \<bar>a\<bar>"
+    and abs_of_nonneg [simp]: "0 \<le> a \<Longrightarrow> \<bar>a\<bar> = a"
+    and abs_leI: "a \<le> b \<Longrightarrow> - a \<le> b \<Longrightarrow> \<bar>a\<bar> \<le> b"
+    and abs_eq_0 [simp]: "\<bar>a\<bar> = 0 \<longleftrightarrow> a = 0"
+    and abs_minus_cancel [simp]: "\<bar>-a\<bar> = \<bar>a\<bar>"
+    and abs_idempotent [simp]: "\<bar>\<bar>a\<bar>\<bar> = \<bar>a\<bar>"
+    and abs_triangle_ineq: "\<bar>a + b\<bar> \<le> \<bar>a\<bar> + \<bar>b\<bar>"
 begin
 
 lemma abs_zero [simp]: "\<bar>0\<bar> = 0"
-  by (simp add: abs_lattice)
-
-lemma abs_eq_0 [simp]: "\<bar>a\<bar> = 0 \<longleftrightarrow> a = 0"
-  by (simp add: abs_lattice)
+  by simp
 
 lemma abs_0_eq [simp, noatp]: "0 = \<bar>a\<bar> \<longleftrightarrow> a = 0"
 proof -
-  have "(0 = abs a) = (abs a = 0)" by (simp only: eq_ac)
+  have "0 = \<bar>a\<bar> \<longleftrightarrow> \<bar>a\<bar> = 0" by (simp only: eq_ac)
   thus ?thesis by simp
 qed
 
-lemma neg_inf_eq_sup [simp]: "- inf a b = sup (-a) (-b)"
-  by (simp add: inf_eq_neg_sup)
-
-lemma neg_sup_eq_inf [simp]: "- sup a b = inf (-a) (-b)"
-  by (simp del: neg_inf_eq_sup add: sup_eq_neg_inf)
-
-lemma abs_ge_zero [simp]: "0 \<le> \<bar>a\<bar>"
-proof -
-  have a: "a \<le> \<bar>a\<bar>" and b: "- a \<le> \<bar>a\<bar>" by (auto simp add: abs_lattice)
-  show ?thesis by (rule add_mono [OF a b, simplified])
-qed
-  
 lemma abs_le_zero_iff [simp]: "\<bar>a\<bar> \<le> 0 \<longleftrightarrow> a = 0" 
 proof
   assume "\<bar>a\<bar> \<le> 0"
@@ -955,20 +1024,11 @@
   show ?thesis by (simp add: a)
 qed
 
-lemma abs_ge_self: "a \<le> \<bar>a\<bar>"
-  by (auto simp add: abs_lattice)
-
 lemma abs_ge_minus_self: "- a \<le> \<bar>a\<bar>"
-  by (auto simp add: abs_lattice)
-
-lemma abs_minus_cancel [simp]: "\<bar>-a\<bar> = \<bar>a\<bar>"
-  by (simp add: abs_lattice sup_commute)
-
-lemma abs_idempotent [simp]: "\<bar>\<bar>a\<bar>\<bar> = \<bar>a\<bar>"
-apply (simp add: abs_lattice [of "abs a"])
-apply (subst sup_absorb1)
-apply (rule order_trans [of _ zero])
-by auto
+proof -
+  have "- a \<le> \<bar>-a\<bar>" by (rule abs_ge_self)
+  then show ?thesis by simp
+qed
 
 lemma abs_minus_commute: 
   "\<bar>a - b\<bar> = \<bar>b - a\<bar>"
@@ -978,73 +1038,24 @@
   finally show ?thesis .
 qed
 
-lemma abs_prts: "\<bar>a\<bar> = pprt a - nprt a"
+lemma abs_of_pos: "0 < a \<Longrightarrow> \<bar>a\<bar> = a"
+  by (rule abs_of_nonneg, rule less_imp_le)
+
+lemma abs_of_nonpos [simp]:
+  assumes "a \<le> 0"
+  shows "\<bar>a\<bar> = - a"
 proof -
-  have "0 \<le> \<bar>a\<bar>" by simp
-  then have "0 \<le> sup a (- a)" unfolding abs_lattice .
-  then have "sup (sup a (- a)) 0 = sup a (- a)" by (rule sup_absorb1)
-  then show ?thesis
-    by (simp add: add_sup_inf_distribs sup_ACI
-      pprt_def nprt_def diff_minus abs_lattice)
+  let ?b = "- a"
+  have "- ?b \<le> 0 \<Longrightarrow> \<bar>- ?b\<bar> = - (- ?b)"
+  unfolding abs_minus_cancel [of "?b"]
+  unfolding neg_le_0_iff_le [of "?b"]
+  unfolding minus_minus by (erule abs_of_nonneg)
+  then show ?thesis using assms by auto
 qed
   
-lemma zero_le_iff_zero_nprt: "0 \<le> a \<longleftrightarrow> nprt a = 0"
-  by (simp add: le_iff_inf nprt_def inf_commute)
-
-lemma le_zero_iff_zero_pprt: "a \<le> 0 \<longleftrightarrow> pprt a = 0"
-  by (simp add: le_iff_sup pprt_def sup_commute)
-
-lemma le_zero_iff_pprt_id: "0 \<le> a \<longleftrightarrow> pprt a = a"
-  by (simp add: le_iff_sup pprt_def sup_commute)
-
-lemma zero_le_iff_nprt_id: "a \<le> 0 \<longleftrightarrow> nprt a = a"
-by (simp add: le_iff_inf nprt_def inf_commute)
-
-lemma pprt_mono [simp, noatp]: "a \<le> b \<Longrightarrow> pprt a \<le> pprt b"
-  by (simp add: le_iff_sup pprt_def sup_ACI sup_assoc [symmetric, of a])
-
-lemma nprt_mono [simp, noatp]: "a \<le> b \<Longrightarrow> nprt a \<le> nprt b"
-  by (simp add: le_iff_inf nprt_def inf_ACI inf_assoc [symmetric, of a])
-
-lemma pprt_neg: "pprt (- x) = - nprt x"
-  by (simp add: pprt_def nprt_def)
-
-lemma nprt_neg: "nprt (- x) = - pprt x"
-  by (simp add: pprt_def nprt_def)
-
-lemma abs_of_nonneg [simp]: "0 \<le> a \<Longrightarrow> \<bar>a\<bar> = a"
-  by (simp add: iffD1 [OF zero_le_iff_zero_nprt]
-    iffD1[OF le_zero_iff_pprt_id] abs_prts)
-
-lemma abs_of_pos: "0 < x \<Longrightarrow> \<bar>x\<bar> = x"
-  by (rule abs_of_nonneg, rule less_imp_le)
-
-lemma abs_of_nonpos [simp]: "a \<le> 0 \<Longrightarrow> \<bar>a\<bar> = - a"
-  by (simp add: iffD1 [OF le_zero_iff_zero_pprt]
-    iffD1 [OF zero_le_iff_nprt_id] abs_prts)
-
-lemma abs_of_neg: "x < 0 \<Longrightarrow> \<bar>x\<bar> = - x"
+lemma abs_of_neg: "a < 0 \<Longrightarrow> \<bar>a\<bar> = - a"
   by (rule abs_of_nonpos, rule less_imp_le)
 
-lemma abs_leI: "a \<le> b \<Longrightarrow> - a \<le> b \<Longrightarrow> \<bar>a\<bar> \<le> b"
-  by (simp add: abs_lattice le_supI)
-
-lemma le_minus_self_iff: "a \<le> - a \<longleftrightarrow> a \<le> 0"
-proof -
-  from add_le_cancel_left [of "uminus a" "plus a a" zero]
-  have "(a <= -a) = (a+a <= 0)" 
-    by (simp add: add_assoc[symmetric])
-  thus ?thesis by simp
-qed
-
-lemma minus_le_self_iff: "- a \<le> a \<longleftrightarrow> 0 \<le> a"
-proof -
-  from add_le_cancel_left [of "uminus a" zero "plus a a"]
-  have "(-a <= a) = (0 <= a+a)" 
-    by (simp add: add_assoc[symmetric])
-  thus ?thesis by simp
-qed
-
 lemma abs_le_D1: "\<bar>a\<bar> \<le> b \<Longrightarrow> a \<le> b"
   by (insert abs_ge_self, blast intro: order_trans)
 
@@ -1054,20 +1065,6 @@
 lemma abs_le_iff: "\<bar>a\<bar> \<le> b \<longleftrightarrow> a \<le> b \<and> - a \<le> b"
   by (blast intro: abs_leI dest: abs_le_D1 abs_le_D2)
 
-lemma abs_triangle_ineq: "\<bar>a + b\<bar> \<le> \<bar>a\<bar> + \<bar>b\<bar>"
-proof -
-  have g:"abs a + abs b = sup (a+b) (sup (-a-b) (sup (-a+b) (a + (-b))))" (is "_=sup ?m ?n")
-    by (simp add: abs_lattice add_sup_inf_distribs sup_ACI diff_minus)
-  have a:"a+b <= sup ?m ?n" by (simp)
-  have b:"-a-b <= ?n" by (simp) 
-  have c:"?n <= sup ?m ?n" by (simp)
-  from b c have d: "-a-b <= sup ?m ?n" by(rule order_trans)
-  have e:"-a-b = -(a+b)" by (simp add: diff_minus)
-  from a d e have "abs(a+b) <= sup ?m ?n" 
-    by (drule_tac abs_leI, auto)
-  with g[symmetric] show ?thesis by simp
-qed
-
 lemma abs_triangle_ineq2: "\<bar>a\<bar> - \<bar>b\<bar> \<le> \<bar>a - b\<bar>"
   apply (simp add: compare_rls)
   apply (subgoal_tac "abs a = abs (plus (minus a b) b)")
@@ -1102,7 +1099,7 @@
   finally show ?thesis .
 qed
 
-lemma abs_add_abs[simp]:
+lemma abs_add_abs [simp]:
   "\<bar>\<bar>a\<bar> + \<bar>b\<bar>\<bar> = \<bar>a\<bar> + \<bar>b\<bar>" (is "?L = ?R")
 proof (rule antisym)
   show "?L \<ge> ?R" by(rule abs_ge_self)
@@ -1114,6 +1111,87 @@
 
 end
 
+
+class lordered_ab_group_abs = lordered_ab_group + abs +
+  assumes abs_lattice: "\<bar>a\<bar> = sup a (- a)"
+begin
+
+lemma abs_prts: "\<bar>a\<bar> = pprt a - nprt a"
+proof -
+  have "0 \<le> \<bar>a\<bar>"
+  proof -
+    have a: "a \<le> \<bar>a\<bar>" and b: "- a \<le> \<bar>a\<bar>" by (auto simp add: abs_lattice)
+    show ?thesis by (rule add_mono [OF a b, simplified])
+  qed
+  then have "0 \<le> sup a (- a)" unfolding abs_lattice .
+  then have "sup (sup a (- a)) 0 = sup a (- a)" by (rule sup_absorb1)
+  then show ?thesis
+    by (simp add: add_sup_inf_distribs sup_ACI
+      pprt_def nprt_def diff_minus abs_lattice)
+qed
+
+subclass pordered_ab_group_add_abs
+proof -
+  have abs_ge_zero [simp]: "\<And>a. 0 \<le> \<bar>a\<bar>"
+  proof -
+    fix a b
+    have a: "a \<le> \<bar>a\<bar>" and b: "- a \<le> \<bar>a\<bar>" by (auto simp add: abs_lattice)
+    show "0 \<le> \<bar>a\<bar>" by (rule add_mono [OF a b, simplified])
+  qed
+  have abs_leI: "\<And>a b. a \<le> b \<Longrightarrow> - a \<le> b \<Longrightarrow> \<bar>a\<bar> \<le> b"
+    by (simp add: abs_lattice le_supI)
+  show ?thesis
+  proof unfold_locales
+    fix a
+    show "0 \<le> \<bar>a\<bar>" by simp
+  next
+    fix a
+    show "a \<le> \<bar>a\<bar>"
+      by (auto simp add: abs_lattice)
+  next
+    fix a
+    show "\<bar>a\<bar> = 0 \<longleftrightarrow> a = 0"
+      by (simp add: abs_lattice)
+  next
+    fix a
+    show "\<bar>-a\<bar> = \<bar>a\<bar>"
+      by (simp add: abs_lattice sup_commute)
+  next
+    fix a
+    show "\<bar>\<bar>a\<bar>\<bar> = \<bar>a\<bar>"
+    apply (simp add: abs_lattice [of "abs a"])
+    apply (subst sup_absorb1)
+    apply (rule order_trans [of _ zero])
+    apply auto
+    done
+  next
+    fix a
+    show "0 \<le> a \<Longrightarrow> \<bar>a\<bar> = a"
+      by (simp add: iffD1 [OF zero_le_iff_zero_nprt]
+        iffD1[OF le_zero_iff_pprt_id] abs_prts)
+  next
+    fix a b
+    show "a \<le> b \<Longrightarrow> - a \<le> b \<Longrightarrow> \<bar>a\<bar> \<le> b" by (erule abs_leI)
+  next
+    fix a b
+    show "\<bar>a + b\<bar> \<le> \<bar>a\<bar> + \<bar>b\<bar>"
+    proof -
+      have g:"abs a + abs b = sup (a+b) (sup (-a-b) (sup (-a+b) (a + (-b))))" (is "_=sup ?m ?n")
+        by (simp add: abs_lattice add_sup_inf_distribs sup_ACI diff_minus)
+      have a:"a+b <= sup ?m ?n" by (simp)
+      have b:"-a-b <= ?n" by (simp) 
+      have c:"?n <= sup ?m ?n" by (simp)
+      from b c have d: "-a-b <= sup ?m ?n" by(rule order_trans)
+      have e:"-a-b = -(a+b)" by (simp add: diff_minus)
+      from a d e have "abs(a+b) <= sup ?m ?n" 
+        by (drule_tac abs_leI, auto)
+      with g[symmetric] show ?thesis by simp
+    qed
+  qed auto
+qed
+
+end
+
 lemma sup_eq_if:
   fixes a :: "'a\<Colon>{lordered_ab_group, linorder}"
   shows "sup a (- a) = (if a < 0 then - a else a)"
@@ -1168,13 +1246,6 @@
   apply (simp_all add: prems)
   done
 
-lemmas group_simps =
-  mult_ac
-  add_ac
-  add_diff_eq diff_add_eq diff_diff_eq diff_diff_eq2
-  diff_eq_eq eq_diff_eq diff_minus [symmetric] uminus_add_conv_diff
-  diff_less_eq less_diff_eq diff_le_eq le_diff_eq
-
 lemma estimate_by_abs:
   "a + b <= (c::'a::lordered_ab_group_abs) \<Longrightarrow> a <= c + abs b" 
 proof -
diff -r 2673709fb8f7 -r 022029099a83 src/HOL/Presburger.thy
--- a/src/HOL/Presburger.thy	Mon Oct 29 17:08:01 2007 +0100
+++ b/src/HOL/Presburger.thy	Tue Oct 30 08:45:54 2007 +0100
@@ -703,6 +703,8 @@
   less_Bit0_Min less_Bit1_Min less_Bit_Bit0 less_Bit1_Bit less_Bit0_Bit1
   less_number_of
 
+context ring_1
+begin
 
 lemma of_int_num [code func]:
   "of_int k = (if k = 0 then 0 else if k < 0 then
@@ -737,3 +739,5 @@
 qed
 
 end
+
+end
diff -r 2673709fb8f7 -r 022029099a83 src/HOL/Ring_and_Field.thy
--- a/src/HOL/Ring_and_Field.thy	Mon Oct 29 17:08:01 2007 +0100
+++ b/src/HOL/Ring_and_Field.thy	Tue Oct 30 08:45:54 2007 +0100
@@ -153,17 +153,25 @@
 lemmas ring_distribs =
   right_distrib left_distrib left_diff_distrib right_diff_distrib
 
+lemmas ring_simps =
+  add_ac
+  add_diff_eq diff_add_eq diff_diff_eq diff_diff_eq2
+  diff_eq_eq eq_diff_eq diff_minus [symmetric] uminus_add_conv_diff
+  ring_distribs
+
+lemma eq_add_iff1:
+  "a * e + c = b * e + d \<longleftrightarrow> (a - b) * e + c = d"
+  by (simp add: ring_simps)
+
+lemma eq_add_iff2:
+  "a * e + c = b * e + d \<longleftrightarrow> c = (b - a) * e + d"
+  by (simp add: ring_simps)
+
 end
 
 lemmas ring_distribs =
   right_distrib left_distrib left_diff_distrib right_diff_distrib
 
-text{*This list of rewrites simplifies ring terms by multiplying
-everything out and bringing sums and products into a canonical form
-(by ordered rewriting). As a result it decides ring equalities but
-also helps with inequalities. *}
-lemmas ring_simps = group_simps ring_distribs
-
 class comm_ring = comm_semiring + ab_group_add
 
 subclass (in comm_ring) ring by unfold_locales
@@ -180,6 +188,18 @@
 subclass (in comm_ring_1) comm_semiring_1_cancel by unfold_locales
 
 class ring_no_zero_divisors = ring + no_zero_divisors
+begin
+
+lemma mult_eq_0_iff [simp]:
+  shows "a * b = 0 \<longleftrightarrow> (a = 0 \<or> b = 0)"
+proof (cases "a = 0 \<or> b = 0")
+  case False then have "a \<noteq> 0" and "b \<noteq> 0" by auto
+    then show ?thesis using no_zero_divisors by simp
+next
+  case True then show ?thesis by auto
+qed
+
+end
 
 class ring_1_no_zero_divisors = ring_1 + ring_no_zero_divisors
 
@@ -226,16 +246,75 @@
   thus "inverse a * a = 1" by (rule field_inverse)
   thus "a * inverse a = 1" by (simp only: mult_commute)
 qed
+
 subclass (in field) idom by unfold_locales
 
+context field
+begin
+
+lemma right_inverse_eq: "b \<noteq> 0 \<Longrightarrow> a / b = 1 \<longleftrightarrow> a = b"
+proof
+  assume neq: "b \<noteq> 0"
+  {
+    hence "a = (a / b) * b" by (simp add: divide_inverse mult_ac)
+    also assume "a / b = 1"
+    finally show "a = b" by simp
+  next
+    assume "a = b"
+    with neq show "a / b = 1" by (simp add: divide_inverse)
+  }
+qed
+
+lemma nonzero_inverse_eq_divide: "a \<noteq> 0 \<Longrightarrow> inverse a = 1 / a"
+  by (simp add: divide_inverse)
+
+lemma divide_self [simp]: "a \<noteq> 0 \<Longrightarrow> a / a = 1"
+  by (simp add: divide_inverse)
+
+lemma divide_zero_left [simp]: "0 / a = 0"
+  by (simp add: divide_inverse)
+
+lemma inverse_eq_divide: "inverse a = 1 / a"
+  by (simp add: divide_inverse)
+
+lemma add_divide_distrib: "(a+b) / c = a/c + b/c"
+  by (simp add: divide_inverse ring_distribs) 
+
+end
+
 class division_by_zero = zero + inverse +
   assumes inverse_zero [simp]: "inverse 0 = 0"
 
+lemma divide_zero [simp]:
+  "a / 0 = (0::'a::{field,division_by_zero})"
+  by (simp add: divide_inverse)
+
+lemma divide_self_if [simp]:
+  "a / (a::'a::{field,division_by_zero}) = (if a=0 then 0 else 1)"
+  by (simp add: divide_self)
+
 class mult_mono = times + zero + ord +
   assumes mult_left_mono: "a \<le> b \<Longrightarrow> 0 \<le> c \<Longrightarrow> c * a \<le> c * b"
   assumes mult_right_mono: "a \<le> b \<Longrightarrow> 0 \<le> c \<Longrightarrow> a * c \<le> b * c"
 
 class pordered_semiring = mult_mono + semiring_0 + pordered_ab_semigroup_add 
+begin
+
+lemma mult_mono:
+  "a \<le> b \<Longrightarrow> c \<le> d \<Longrightarrow> 0 \<le> b \<Longrightarrow> 0 \<le> c
+     \<Longrightarrow> a * c \<le> b * d"
+apply (erule mult_right_mono [THEN order_trans], assumption)
+apply (erule mult_left_mono, assumption)
+done
+
+lemma mult_mono':
+  "a \<le> b \<Longrightarrow> c \<le> d \<Longrightarrow> 0 \<le> a \<Longrightarrow> 0 \<le> c
+     \<Longrightarrow> a * c \<le> b * d"
+apply (rule mult_mono)
+apply (fast intro: order_trans)+
+done
+
+end
 
 class pordered_cancel_semiring = mult_mono + pordered_ab_semigroup_add
   + semiring + comm_monoid_add + cancel_ab_semigroup_add
@@ -243,10 +322,37 @@
 subclass (in pordered_cancel_semiring) semiring_0_cancel by unfold_locales
 subclass (in pordered_cancel_semiring) pordered_semiring by unfold_locales
 
-class ordered_semiring = semiring + comm_monoid_add + ordered_cancel_ab_semigroup_add + mult_mono
+context pordered_cancel_semiring
 begin
 
-subclass pordered_cancel_semiring by unfold_locales
+lemma mult_nonneg_nonneg: "0 \<le> a \<Longrightarrow> 0 \<le> b \<Longrightarrow> 0 \<le> a * b"
+  by (drule mult_left_mono [of zero b], auto)
+
+lemma mult_nonneg_nonpos: "0 \<le> a \<Longrightarrow> b \<le> 0 \<Longrightarrow> a * b \<le> 0"
+  by (drule mult_left_mono [of b zero], auto)
+
+lemma mult_nonneg_nonpos2: "0 \<le> a \<Longrightarrow> b \<le> 0 \<Longrightarrow> b * a \<le> 0" 
+  by (drule mult_right_mono [of b zero], auto)
+
+lemma split_mult_neg_le: "(0 \<le> a & b \<le> 0) | (a \<le> 0 & 0 \<le> b) \<Longrightarrow> a * b \<le> (0::_::pordered_cancel_semiring)" 
+  by (auto simp add: mult_nonneg_nonpos mult_nonneg_nonpos2)
+
+end
+
+class ordered_semiring = semiring + comm_monoid_add + ordered_cancel_ab_semigroup_add + mult_mono
+
+subclass (in ordered_semiring) pordered_cancel_semiring by unfold_locales
+
+context ordered_semiring
+begin
+
+lemma mult_left_less_imp_less:
+  "c * a < c * b \<Longrightarrow> 0 \<le> c \<Longrightarrow> a < b"
+  by (force simp add: mult_left_mono not_le [symmetric])
+ 
+lemma mult_right_less_imp_less:
+  "a * c < b * c \<Longrightarrow> 0 \<le> c \<Longrightarrow> a < b"
+  by (force simp add: mult_right_mono not_le [symmetric])
 
 end
 
@@ -268,8 +374,49 @@
     using mult_strict_right_mono by (cases "c = 0") auto
 qed
 
+context ordered_semiring_strict
+begin
+
+lemma mult_left_le_imp_le:
+  "c * a \<le> c * b \<Longrightarrow> 0 < c \<Longrightarrow> a \<le> b"
+  by (force simp add: mult_strict_left_mono _not_less [symmetric])
+ 
+lemma mult_right_le_imp_le:
+  "a * c \<le> b * c \<Longrightarrow> 0 < c \<Longrightarrow> a \<le> b"
+  by (force simp add: mult_strict_right_mono not_less [symmetric])
+
+lemma mult_pos_pos:
+  "0 < a \<Longrightarrow> 0 < b \<Longrightarrow> 0 < a * b"
+  by (drule mult_strict_left_mono [of zero b], auto)
+
+lemma mult_pos_neg:
+  "0 < a \<Longrightarrow> b < 0 \<Longrightarrow> a * b < 0"
+  by (drule mult_strict_left_mono [of b zero], auto)
+
+lemma mult_pos_neg2:
+  "0 < a \<Longrightarrow> b < 0 \<Longrightarrow> b * a < 0" 
+  by (drule mult_strict_right_mono [of b zero], auto)
+
+lemma zero_less_mult_pos:
+  "0 < a * b \<Longrightarrow> 0 < a \<Longrightarrow> 0 < b"
+apply (cases "b\<le>0") 
+ apply (auto simp add: le_less not_less)
+apply (drule_tac mult_pos_neg [of a b]) 
+ apply (auto dest: less_not_sym)
+done
+
+lemma zero_less_mult_pos2:
+  "0 < b * a \<Longrightarrow> 0 < a \<Longrightarrow> 0 < b"
+apply (cases "b\<le>0") 
+ apply (auto simp add: le_less not_less)
+apply (drule_tac mult_pos_neg2 [of a b]) 
+ apply (auto dest: less_not_sym)
+done
+
+end
+
 class mult_mono1 = times + zero + ord +
-  assumes mult_mono: "a \<le> b \<Longrightarrow> 0 \<le> c \<Longrightarrow> c * a \<le> c * b"
+  assumes mult_mono1: "a \<le> b \<Longrightarrow> 0 \<le> c \<Longrightarrow> c * a \<le> c * b"
 
 class pordered_comm_semiring = comm_semiring_0
   + pordered_ab_semigroup_add + mult_mono1
@@ -289,7 +436,7 @@
 proof unfold_locales
   fix a b c :: 'a
   assume "a \<le> b" "0 \<le> c"
-  thus "c * a \<le> c * b" by (rule mult_mono)
+  thus "c * a \<le> c * b" by (rule mult_mono1)
   thus "a * c \<le> b * c" by (simp only: mult_commute)
 qed
 
@@ -314,9 +461,49 @@
 qed
 
 class pordered_ring = ring + pordered_cancel_semiring 
+
+subclass (in pordered_ring) pordered_ab_group_add by unfold_locales
+
+context pordered_ring
 begin
 
-subclass pordered_ab_group_add by unfold_locales
+lemmas ring_simps = ring_simps group_simps
+
+lemma less_add_iff1:
+  "a * e + c < b * e + d \<longleftrightarrow> (a - b) * e + c < d"
+  by (simp add: ring_simps)
+
+lemma less_add_iff2:
+  "a * e + c < b * e + d \<longleftrightarrow> c < (b - a) * e + d"
+  by (simp add: ring_simps)
+
+lemma le_add_iff1:
+  "a * e + c \<le> b * e + d \<longleftrightarrow> (a - b) * e + c \<le> d"
+  by (simp add: ring_simps)
+
+lemma le_add_iff2:
+  "a * e + c \<le> b * e + d \<longleftrightarrow> c \<le> (b - a) * e + d"
+  by (simp add: ring_simps)
+
+lemma mult_left_mono_neg:
+  "b \<le> a \<Longrightarrow> c \<le> 0 \<Longrightarrow> c * a \<le> c * b"
+  apply (drule mult_left_mono [of _ _ "uminus c"])
+  apply (simp_all add: minus_mult_left [symmetric]) 
+  done
+
+lemma mult_right_mono_neg:
+  "b \<le> a \<Longrightarrow> c \<le> 0 \<Longrightarrow> a * c \<le> b * c"
+  apply (drule mult_right_mono [of _ _ "uminus c"])
+  apply (simp_all add: minus_mult_right [symmetric]) 
+  done
+
+lemma mult_nonpos_nonpos:
+  "a \<le> 0 \<Longrightarrow> b \<le> 0 \<Longrightarrow> 0 \<le> a * b"
+  by (drule mult_right_mono_neg [of a zero b]) auto
+
+lemma split_mult_pos_le:
+  "(0 \<le> a \<and> 0 \<le> b) \<or> (a \<le> 0 \<and> b \<le> 0) \<Longrightarrow> 0 \<le> a * b"
+  by (auto simp add: mult_nonneg_nonneg mult_nonpos_nonpos)
 
 end
 
@@ -331,12 +518,10 @@
 class sgn_if = sgn + zero + one + minus + ord +
   assumes sgn_if: "sgn x = (if x = 0 then 0 else if 0 < x then 1 else - 1)"
 
-(* The "strict" suffix can be seen as describing the combination of ordered_ring and no_zero_divisors.
-   Basically, ordered_ring + no_zero_divisors = ordered_ring_strict.
- *)
-class ordered_ring = ring + ordered_semiring + lordered_ab_group + abs_if
-
--- {*FIXME: continue localization here*}
+class ordered_ring = ring + ordered_semiring
+  + lordered_ab_group + abs_if
+  -- {*FIXME: should inherit from ordered_ab_group_add rather than
+         lordered_ab_group*}
 
 instance ordered_ring \<subseteq> lordered_ring
 proof 
@@ -345,167 +530,44 @@
     by (simp only: abs_if sup_eq_if)
 qed
 
-class ordered_ring_strict =
-  ring + ordered_semiring_strict + lordered_ab_group + abs_if
-
-instance ordered_ring_strict \<subseteq> ordered_ring ..
-
-class pordered_comm_ring = comm_ring + pordered_comm_semiring
-
-instance pordered_comm_ring \<subseteq> pordered_ring ..
-
-instance pordered_comm_ring \<subseteq> pordered_cancel_comm_semiring ..
-
-class ordered_semidom = comm_semiring_1_cancel + ordered_comm_semiring_strict +
-  (*previously ordered_semiring*)
-  assumes zero_less_one [simp]: "0 < 1"
-
-lemma pos_add_strict:
-  fixes a b c :: "'a\<Colon>ordered_semidom"
-  shows "0 < a \<Longrightarrow> b < c \<Longrightarrow> b < a + c"
-  using add_strict_mono [of 0 a b c] by simp
-
-class ordered_idom =
-  comm_ring_1 +
-  ordered_comm_semiring_strict +
-  lordered_ab_group +
-  abs_if + sgn_if
-  (*previously ordered_ring*)
-
-instance ordered_idom \<subseteq> ordered_ring_strict ..
-
-instance ordered_idom \<subseteq> pordered_comm_ring ..
-
-class ordered_field = field + ordered_idom
-
-lemma linorder_neqE_ordered_idom:
-  fixes x y :: "'a :: ordered_idom"
-  assumes "x \<noteq> y" obtains "x < y" | "y < x"
-  using assms by (rule linorder_neqE)
+(* The "strict" suffix can be seen as describing the combination of ordered_ring and no_zero_divisors.
+   Basically, ordered_ring + no_zero_divisors = ordered_ring_strict.
+ *)
+class ordered_ring_strict = ring + ordered_semiring_strict
+  + lordered_ab_group + abs_if
+  -- {*FIXME: should inherit from ordered_ab_group_add rather than
+         lordered_ab_group*}
 
-lemma eq_add_iff1:
-  "(a*e + c = b*e + d) = ((a-b)*e + c = (d::'a::ring))"
-by (simp add: ring_simps)
-
-lemma eq_add_iff2:
-  "(a*e + c = b*e + d) = (c = (b-a)*e + (d::'a::ring))"
-by (simp add: ring_simps)
-
-lemma less_add_iff1:
-  "(a*e + c < b*e + d) = ((a-b)*e + c < (d::'a::pordered_ring))"
-by (simp add: ring_simps)
-
-lemma less_add_iff2:
-  "(a*e + c < b*e + d) = (c < (b-a)*e + (d::'a::pordered_ring))"
-by (simp add: ring_simps)
-
-lemma le_add_iff1:
-  "(a*e + c \<le> b*e + d) = ((a-b)*e + c \<le> (d::'a::pordered_ring))"
-by (simp add: ring_simps)
+instance ordered_ring_strict \<subseteq> ordered_ring by intro_classes
 
-lemma le_add_iff2:
-  "(a*e + c \<le> b*e + d) = (c \<le> (b-a)*e + (d::'a::pordered_ring))"
-by (simp add: ring_simps)
-
-
-subsection {* Ordering Rules for Multiplication *}
-
-lemma mult_left_le_imp_le:
-  "[|c*a \<le> c*b; 0 < c|] ==> a \<le> (b::'a::ordered_semiring_strict)"
-by (force simp add: mult_strict_left_mono linorder_not_less [symmetric])
- 
-lemma mult_right_le_imp_le:
-  "[|a*c \<le> b*c; 0 < c|] ==> a \<le> (b::'a::ordered_semiring_strict)"
-by (force simp add: mult_strict_right_mono linorder_not_less [symmetric])
-
-lemma mult_left_less_imp_less:
-  "[|c*a < c*b; 0 \<le> c|] ==> a < (b::'a::ordered_semiring)"
-by (force simp add: mult_left_mono linorder_not_le [symmetric])
- 
-lemma mult_right_less_imp_less:
-  "[|a*c < b*c; 0 \<le> c|] ==> a < (b::'a::ordered_semiring)"
-by (force simp add: mult_right_mono linorder_not_le [symmetric])
+context ordered_ring_strict
+begin
 
 lemma mult_strict_left_mono_neg:
-  "[|b < a; c < 0|] ==> c * a < c * (b::'a::ordered_ring_strict)"
-apply (drule mult_strict_left_mono [of _ _ "-c"])
-apply (simp_all add: minus_mult_left [symmetric]) 
-done
-
-lemma mult_left_mono_neg:
-  "[|b \<le> a; c \<le> 0|] ==> c * a \<le>  c * (b::'a::pordered_ring)"
-apply (drule mult_left_mono [of _ _ "-c"])
-apply (simp_all add: minus_mult_left [symmetric]) 
-done
+  "b < a \<Longrightarrow> c < 0 \<Longrightarrow> c * a < c * b"
+  apply (drule mult_strict_left_mono [of _ _ "uminus c"])
+  apply (simp_all add: minus_mult_left [symmetric]) 
+  done
 
 lemma mult_strict_right_mono_neg:
-  "[|b < a; c < 0|] ==> a * c < b * (c::'a::ordered_ring_strict)"
-apply (drule mult_strict_right_mono [of _ _ "-c"])
-apply (simp_all add: minus_mult_right [symmetric]) 
-done
-
-lemma mult_right_mono_neg:
-  "[|b \<le> a; c \<le> 0|] ==> a * c \<le>  (b::'a::pordered_ring) * c"
-apply (drule mult_right_mono [of _ _ "-c"])
-apply (simp)
-apply (simp_all add: minus_mult_right [symmetric]) 
-done
-
-
-subsection{* Products of Signs *}
-
-lemma mult_pos_pos: "[| (0::'a::ordered_semiring_strict) < a; 0 < b |] ==> 0 < a*b"
-by (drule mult_strict_left_mono [of 0 b], auto)
-
-lemma mult_nonneg_nonneg: "[| (0::'a::pordered_cancel_semiring) \<le> a; 0 \<le> b |] ==> 0 \<le> a*b"
-by (drule mult_left_mono [of 0 b], auto)
-
-lemma mult_pos_neg: "[| (0::'a::ordered_semiring_strict) < a; b < 0 |] ==> a*b < 0"
-by (drule mult_strict_left_mono [of b 0], auto)
-
-lemma mult_nonneg_nonpos: "[| (0::'a::pordered_cancel_semiring) \<le> a; b \<le> 0 |] ==> a*b \<le> 0"
-by (drule mult_left_mono [of b 0], auto)
+  "b < a \<Longrightarrow> c < 0 \<Longrightarrow> a * c < b * c"
+  apply (drule mult_strict_right_mono [of _ _ "uminus c"])
+  apply (simp_all add: minus_mult_right [symmetric]) 
+  done
 
-lemma mult_pos_neg2: "[| (0::'a::ordered_semiring_strict) < a; b < 0 |] ==> b*a < 0" 
-by (drule mult_strict_right_mono[of b 0], auto)
-
-lemma mult_nonneg_nonpos2: "[| (0::'a::pordered_cancel_semiring) \<le> a; b \<le> 0 |] ==> b*a \<le> 0" 
-by (drule mult_right_mono[of b 0], auto)
-
-lemma mult_neg_neg: "[| a < (0::'a::ordered_ring_strict); b < 0 |] ==> 0 < a*b"
-by (drule mult_strict_right_mono_neg, auto)
-
-lemma mult_nonpos_nonpos: "[| a \<le> (0::'a::pordered_ring); b \<le> 0 |] ==> 0 \<le> a*b"
-by (drule mult_right_mono_neg[of a 0 b ], auto)
+lemma mult_neg_neg:
+  "a < 0 \<Longrightarrow> b < 0 \<Longrightarrow> 0 < a * b"
+  by (drule mult_strict_right_mono_neg, auto)
 
-lemma zero_less_mult_pos:
-     "[| 0 < a*b; 0 < a|] ==> 0 < (b::'a::ordered_semiring_strict)"
-apply (cases "b\<le>0") 
- apply (auto simp add: order_le_less linorder_not_less)
-apply (drule_tac mult_pos_neg [of a b]) 
- apply (auto dest: order_less_not_sym)
-done
-
-lemma zero_less_mult_pos2:
-     "[| 0 < b*a; 0 < a|] ==> 0 < (b::'a::ordered_semiring_strict)"
-apply (cases "b\<le>0") 
- apply (auto simp add: order_le_less linorder_not_less)
-apply (drule_tac mult_pos_neg2 [of a b]) 
- apply (auto dest: order_less_not_sym)
-done
+end
 
 lemma zero_less_mult_iff:
-     "((0::'a::ordered_ring_strict) < a*b) = (0 < a & 0 < b | a < 0 & b < 0)"
-apply (auto simp add: order_le_less linorder_not_less mult_pos_pos 
-  mult_neg_neg)
-apply (blast dest: zero_less_mult_pos) 
-apply (blast dest: zero_less_mult_pos2)
-done
-
-lemma mult_eq_0_iff [simp]:
-  fixes a b :: "'a::ring_no_zero_divisors"
-  shows "(a * b = 0) = (a = 0 \<or> b = 0)"
-by (cases "a = 0 \<or> b = 0", auto dest: no_zero_divisors)
+  fixes a :: "'a::ordered_ring_strict"
+  shows "0 < a * b \<longleftrightarrow> 0 < a \<and> 0 < b \<or> a < 0 \<and> b < 0"
+  apply (auto simp add: le_less not_less mult_pos_pos mult_neg_neg)
+  apply (blast dest: zero_less_mult_pos) 
+  apply (blast dest: zero_less_mult_pos2)
+  done
 
 instance ordered_ring_strict \<subseteq> ring_no_zero_divisors
 apply intro_classes
@@ -530,18 +592,57 @@
 apply (force simp add: minus_mult_left[symmetric]) 
 done
 
-lemma split_mult_pos_le: "(0 \<le> a & 0 \<le> b) | (a \<le> 0 & b \<le> 0) \<Longrightarrow> 0 \<le> a * (b::_::pordered_ring)"
-by (auto simp add: mult_nonneg_nonneg mult_nonpos_nonpos)
-
-lemma split_mult_neg_le: "(0 \<le> a & b \<le> 0) | (a \<le> 0 & 0 \<le> b) \<Longrightarrow> a * b \<le> (0::_::pordered_cancel_semiring)" 
-by (auto simp add: mult_nonneg_nonpos mult_nonneg_nonpos2)
-
 lemma zero_le_square[simp]: "(0::'a::ordered_ring_strict) \<le> a*a"
 by (simp add: zero_le_mult_iff linorder_linear)
 
 lemma not_square_less_zero[simp]: "\<not> (a * a < (0::'a::ordered_ring_strict))"
 by (simp add: not_less)
 
+text{*This list of rewrites simplifies ring terms by multiplying
+everything out and bringing sums and products into a canonical form
+(by ordered rewriting). As a result it decides ring equalities but
+also helps with inequalities. *}
+lemmas ring_simps = group_simps ring_distribs
+
+
+class pordered_comm_ring = comm_ring + pordered_comm_semiring
+
+subclass (in pordered_comm_ring) pordered_ring by unfold_locales
+
+subclass (in pordered_comm_ring) pordered_cancel_comm_semiring by unfold_locales
+
+class ordered_semidom = comm_semiring_1_cancel + ordered_comm_semiring_strict +
+  (*previously ordered_semiring*)
+  assumes zero_less_one [simp]: "0 < 1"
+begin
+
+lemma pos_add_strict:
+  shows "0 < a \<Longrightarrow> b < c \<Longrightarrow> b < a + c"
+  using add_strict_mono [of zero a b c] by simp
+
+end
+
+class ordered_idom =
+  comm_ring_1 +
+  ordered_comm_semiring_strict +
+  lordered_ab_group +
+  abs_if + sgn_if
+  (*previously ordered_ring*)
+
+instance ordered_idom \<subseteq> ordered_ring_strict ..
+
+instance ordered_idom \<subseteq> pordered_comm_ring ..
+
+class ordered_field = field + ordered_idom
+
+lemma linorder_neqE_ordered_idom:
+  fixes x y :: "'a :: ordered_idom"
+  assumes "x \<noteq> y" obtains "x < y" | "y < x"
+  using assms by (rule linorder_neqE)
+
+-- {* FIXME continue localization here *}
+
+
 text{*Proving axiom @{text zero_less_one} makes all @{text ordered_semidom}
       theorems available to members of @{term ordered_idom} *}
 
@@ -587,20 +688,6 @@
 apply (blast intro: order_le_less_trans)+
 done
 
-lemma mult_mono:
-     "[|a \<le> b; c \<le> d; 0 \<le> b; 0 \<le> c|] 
-      ==> a * c  \<le>  b * (d::'a::pordered_semiring)"
-apply (erule mult_right_mono [THEN order_trans], assumption)
-apply (erule mult_left_mono, assumption)
-done
-
-lemma mult_mono':
-     "[|a \<le> b; c \<le> d; 0 \<le> a; 0 \<le> c|] 
-      ==> a * c  \<le>  b * (d::'a::pordered_semiring)"
-apply (rule mult_mono)
-apply (fast intro: order_trans)+
-done
-
 lemma less_1_mult: "[| 1 < m; 1 < n |] ==> 1 < m*(n::'a::ordered_semidom)"
 apply (insert mult_strict_mono [of 1 m 1 n]) 
 apply (simp add:  order_less_trans [OF zero_less_one]) 
@@ -805,43 +892,6 @@
     mult_cancel_left1 mult_cancel_left2
 
 
-subsection {* Fields *}
-
-lemma right_inverse_eq: "b \<noteq> 0 ==> (a / b = 1) = (a = (b::'a::field))"
-proof
-  assume neq: "b \<noteq> 0"
-  {
-    hence "a = (a / b) * b" by (simp add: divide_inverse mult_ac)
-    also assume "a / b = 1"
-    finally show "a = b" by simp
-  next
-    assume "a = b"
-    with neq show "a / b = 1" by (simp add: divide_inverse)
-  }
-qed
-
-lemma nonzero_inverse_eq_divide: "a \<noteq> 0 ==> inverse (a::'a::field) = 1/a"
-by (simp add: divide_inverse)
-
-lemma divide_self[simp]: "a \<noteq> 0 ==> a / (a::'a::field) = 1"
-  by (simp add: divide_inverse)
-
-lemma divide_zero [simp]: "a / 0 = (0::'a::{field,division_by_zero})"
-by (simp add: divide_inverse)
-
-lemma divide_self_if [simp]:
-     "a / (a::'a::{field,division_by_zero}) = (if a=0 then 0 else 1)"
-  by (simp add: divide_self)
-
-lemma divide_zero_left [simp]: "0/a = (0::'a::field)"
-by (simp add: divide_inverse)
-
-lemma inverse_eq_divide: "inverse (a::'a::field) = 1/a"
-by (simp add: divide_inverse)
-
-lemma add_divide_distrib: "(a+b)/(c::'a::field) = a/c + b/c"
-by (simp add: divide_inverse ring_distribs) 
-
 (* what ordering?? this is a straight instance of mult_eq_0_iff
 text{*Compared with @{text mult_eq_0_iff}, this version removes the requirement
       of an ordering.*}
@@ -1871,9 +1921,11 @@
 lemma frac_le: "(0::'a::ordered_field) <= x ==> 
     x <= y ==> 0 < w ==> w <= z  ==> x / z <= y / w"
   apply (rule mult_imp_div_pos_le)
-  apply simp;
-  apply (subst times_divide_eq_left);
+  apply simp
+  apply (subst times_divide_eq_left)
   apply (rule mult_imp_le_div_pos, assumption)
+  thm mult_mono
+  thm mult_mono'
   apply (rule mult_mono)
   apply simp_all
 done