--- a/src/HOL/Deriv.thy Fri Jun 14 08:34:27 2019 +0000
+++ b/src/HOL/Deriv.thy Fri Jun 14 08:34:28 2019 +0000
@@ -1409,12 +1409,14 @@
and dif: "\<And>x. \<lbrakk>a < x; x < b\<rbrakk> \<Longrightarrow> f differentiable (at x)"
shows "\<exists>l z. a < z \<and> z < b \<and> DERIV f z :> l \<and> f b - f a = (b - a) * l"
proof -
- obtain f' where derf: "\<And>x. \<lbrakk>a < x; x < b\<rbrakk> \<Longrightarrow> (f has_derivative f' x) (at x)"
+ obtain f' :: "real \<Rightarrow> real \<Rightarrow> real"
+ where derf: "\<And>x. a < x \<Longrightarrow> x < b \<Longrightarrow> (f has_derivative f' x) (at x)"
using dif unfolding differentiable_def by metis
then obtain z where "a < z" "z < b" "f b - f a = (f' z) (b - a)"
using mvt [OF lt contf] by blast
then show ?thesis
- by (metis derf dif has_derivative_unique has_field_derivative_imp_has_derivative linordered_field_class.sign_simps(5) real_differentiable_def)
+ by (simp add: ac_simps)
+ (metis derf dif has_derivative_unique has_field_derivative_imp_has_derivative real_differentiable_def)
qed
corollary MVT2: