--- a/src/HOL/Probability/Probability_Mass_Function.thy Sun Feb 11 15:03:25 2018 +0100
+++ b/src/HOL/Probability/Probability_Mass_Function.thy Sun Feb 11 18:09:17 2018 +0100
@@ -1571,7 +1571,7 @@
Proof that @{const rel_pmf} preserves orders.
Antisymmetry proof follows Thm. 1 in N. Saheb-Djahromi, Cpo's of measures for nondeterminism,
Theoretical Computer Science 12(1):19--37, 1980,
- \<^url>\<open>http://dx.doi.org/10.1016/0304-3975(80)90003-1\<close>
+ \<^url>\<open>https://doi.org/10.1016/0304-3975(80)90003-1\<close>
\<close>
lemma