About: http://webisa.webdatacommons.org/21844043

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	The example you were looking at is a little harder to visualize, but think about what happens to $f$ on lines other than horizontal and vertical ones.
http://www.w3.org/ns/prov#wasQuotedFrom	stackexchange.com