About: http://webisa.webdatacommons.org/399432817

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	A forward declaration of Piece (or Board) would allow you to use Piece (or Board) as pointers or references or in other ways incomplete types are permissible as well, without requiring the #include.
http://www.w3.org/ns/prov#wasQuotedFrom	gamedev.net