# HG changeset patch # User haftmann # Date 1560501267 0 # Node ID e54caaa38ad991b50d38c7b7e0fcef5ae6330547 # Parent e4d626692640452c2ff3314b8f66d81b141ef04e removed outcommented example which seems not to work as advertized diff -r e4d626692640 -r e54caaa38ad9 src/HOL/Fields.thy --- a/src/HOL/Fields.thy Fri Jun 14 08:34:27 2019 +0000 +++ b/src/HOL/Fields.thy Fri Jun 14 08:34:27 2019 +0000 @@ -904,20 +904,6 @@ of positivity/negativity needed for \field_simps\. Have not added \sign_simps\ to \field_simps\ because the former can lead to case explosions.\ -(* Only works once linear arithmetic is installed: -text{*An example:*} -lemma fixes a b c d e f :: "'a::linordered_field" -shows "\a>b; c \ - ((a-b)*(c-d)*(e-f))/((c-d)*(e-f)*(a-b)) < - ((e-f)*(a-b)*(c-d))/((e-f)*(a-b)*(c-d)) + u" -apply(subgoal_tac "(c-d)*(e-f)*(a-b) > 0") - prefer 2 apply(simp add:sign_simps) -apply(subgoal_tac "(c-d)*(e-f)*(a-b)*u > 0") - prefer 2 apply(simp add:sign_simps) -apply(simp add:field_simps) -done -*) - lemma divide_pos_pos[simp]: "0 < x ==> 0 < y ==> 0 < x / y" by(simp add:field_simps)