--- a/src/HOL/Multivariate_Analysis/Brouwer_Fixpoint.thy Thu Jul 14 14:48:49 2016 +0100
+++ b/src/HOL/Multivariate_Analysis/Brouwer_Fixpoint.thy Thu Jul 14 16:49:22 2016 +0100
@@ -4114,9 +4114,9 @@
have "~ ?rhs \<longleftrightarrow> ~ ?lhs"
proof
assume notr: "~ ?rhs"
- have nog: "\<nexists>g. continuous_on (S \<union> connected_component_set (- S) a) g \<and>
+ have nog: "~ (\<exists>g. continuous_on (S \<union> connected_component_set (- S) a) g \<and>
g ` (S \<union> connected_component_set (- S) a) \<subseteq> sphere 0 1 \<and>
- (\<forall>x\<in>S. g x = (x - a) /\<^sub>R norm (x - a))"
+ (\<forall>x\<in>S. g x = (x - a) /\<^sub>R norm (x - a)))"
if "bounded (connected_component_set (- S) a)"
apply (rule non_extensible_Borsuk_map [OF \<open>compact S\<close> componentsI _ aincc])
using \<open>a \<notin> S\<close> that by auto