About: http://webisa.webdatacommons.org/214759418

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	Thus, sign(x)=1 when x is a positive number, sign(x)=???1 when x is a negative number, and sign(x)=0 when x is 0.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com