diff -r a25b6f79043f -r 575b3a818de5 src/HOL/Analysis/Convex_Euclidean_Space.thy
--- a/src/HOL/Analysis/Convex_Euclidean_Space.thy	Thu Nov 28 20:38:07 2019 +0100
+++ b/src/HOL/Analysis/Convex_Euclidean_Space.thy	Thu Nov 28 23:06:22 2019 +0100
@@ -2233,7 +2233,7 @@
       unfolding 2
       by (clarsimp simp: dist_norm) (metis inner_commute inner_diff_right norm_bound_Basis_le)
     have e': "e = (\<Sum>(i::'a)\<in>Basis. d)"
-      by (simp add: d_def DIM_positive)
+      by (simp add: d_def)
     show "convex hull c \<subseteq> cball x e"
       unfolding 2
       apply clarsimp