src/HOL/Archimedean_Field.thy
changeset 70365 4df0628e8545
parent 68721 53ad5c01be3f
child 75878 fcd118d9242f
--- a/src/HOL/Archimedean_Field.thy	Thu Jul 11 18:37:52 2019 +0200
+++ b/src/HOL/Archimedean_Field.thy	Wed Jul 17 14:02:42 2019 +0100
@@ -26,18 +26,10 @@
       apply (force simp: abs_le_iff bdd_above_def)
       done
   next
+    have *: "\<And>x. x \<in> S \<Longrightarrow> Inf S \<le> x"
+      by (meson abs_le_iff bdd bdd_below_def cInf_lower minus_le_iff)
     show "Sup (uminus ` S) \<le> - Inf S"
-      apply (rule cSup_least)
-      using \<open>S \<noteq> {}\<close>
-       apply force
-      apply clarsimp
-      apply (rule cInf_lower)
-       apply assumption
-      using bdd
-      apply (simp add: bdd_below_def)
-      apply (rule_tac x = "- a" in exI)
-      apply force
-      done
+      using \<open>S \<noteq> {}\<close> by (force intro: * cSup_least)
   qed
   with cSup_abs_le [of "uminus ` S"] assms show ?thesis
     by fastforce
@@ -754,6 +746,9 @@
   finally show "x \<in> \<int>" .
 qed (auto simp: frac_def)
 
+lemma frac_1_eq: "frac (x+1) = frac x"
+  by (simp add: frac_def)
+
 
 subsection \<open>Rounding to the nearest integer\<close>