About: http://webisa.webdatacommons.org/158081040

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	In fact, a dynamic_cast is a technique to determine IF pa is in fact a B. The result of the dynamic_cast is a runtime test, and if pa were not actually a B, then pb would be null.
http://www.w3.org/ns/prov#wasQuotedFrom	codeguru.com