diff -r 12a8f57f68ea -r fdbc7d0ec04f handouts/ho01.tex
--- a/handouts/ho01.tex	Tue Sep 26 14:38:45 2017 +0100
+++ b/handouts/ho01.tex	Wed Sep 27 14:46:20 2017 +0100
@@ -632,7 +632,7 @@
 shown via automata. Even sombody who has written a 700+-page
 book\footnote{\url{http://goo.gl/fD0eHx}} on regular
 exprssions did not know better. Well, we showed it can also be
-done with regular expressions only.\footnote{\url{http://www.inf.kcl.ac.uk/staff/urbanc/Publications/rexp.pdf}} 
+done with regular expressions only.\footnote{\url{http://nms.kcl.ac.uk/christian.urban/Publications/posix.pdf}}
 What a feeling when you are an outsider to the subject!
 
 To conclude: Despite my early ignorance about regular expressions, I