week18.txt: the IRIs in the Isabelle exports are illegal

- find out how to fix them

- probably should contact whoever did this to fix it as well; look
  at ULO paper again, look at how big this problem is

timeline/week18.txt

@@ -27,8 +27,20 @@ Week 18 (27.04.-03.05.)
 		-> RDF [1] uses IRIs which "are a generialization of URI [2]";
 		   IRIs are also defined by the IETF [3]
 
+		-> looking at the grammar of IRIs [3], it indeed seems like the
+		   pipe symbol as used by the ULO exports is in fact not allowed
+		   in IRIs; to quote the IRI grammar
+
+		      iunreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~" / ucschar
+
+		   where ucschar defines various regions of unicode
+		   characters; the lowest of the range is 0xa0, which
+		   is below 0x7c (the pipe symbol)
+
 	[ ] run all quries from ulo paper in graphdb
 
+[ ] fix exported IRIs
+
 [ ] familiarize w/ MathHub infastructure
 
 	[ ] look at tooling; user interface &c