diff -r 1c689d44b297 -r 617c3b0e0a81 handouts/ho01.tex
--- a/handouts/ho01.tex	Mon Oct 01 14:21:37 2018 +0100
+++ b/handouts/ho01.tex	Mon Oct 01 23:55:53 2018 +0100
@@ -695,7 +695,7 @@
 against regular expressions. A similar argument is made in
 
 \begin{center}
-\url{https://elliot.land/validating-an-email-address}
+\url{http://elliot.land/post/its-impossible-to-validate-an-email-address}
 \end{center}