--- a/src/HOL/Multivariate_Analysis/Derivative.thy Wed Dec 30 11:32:56 2015 +0100
+++ b/src/HOL/Multivariate_Analysis/Derivative.thy Wed Dec 30 11:37:29 2015 +0100
@@ -2471,7 +2471,7 @@
unfolding has_vector_derivative_def has_derivative_iff_norm
using assms by (intro conj_cong Lim_cong_within refl) auto
then show ?thesis
- using has_vector_derivative_within_subset[OF f `s \<subseteq> t`] by simp
+ using has_vector_derivative_within_subset[OF f \<open>s \<subseteq> t\<close>] by simp
qed
lemma has_vector_derivative_transform_within: