About: http://webisa.webdatacommons.org/113648536

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	That is, in Expressions 1 to 4, Da(x) and Db(x) can be regarded as Da and Db, respectively, because x is a constant.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com