--- a/handouts/pep-ho.tex	Sat Feb 02 13:38:47 2019 +0000
+++ b/handouts/pep-ho.tex	Wed Mar 20 21:50:20 2019 +0000
@@ -32,6 +32,14 @@
 %from program fragments.
 
 
+%explain graph coloring program (examples from)
+%https://www.metalevel.at/prolog/optimization
+
+
+% nice example for map and reduce using Harry potter characters
+% https://www.matthewgerstman.com/map-filter-reduce/
+
+
 \begin{document}
 \fnote{\copyright{} Christian Urban, King's College London, 2017, 2018}