About: http://webisa.webdatacommons.org/178927422

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	There are a few basic rules how operators can be combined, so e.g. a+*b or x=[b] are invalid, but other than that, you can build any tree you want.
http://www.w3.org/ns/prov#wasQuotedFrom	stackexchange.com