About: http://webisa.webdatacommons.org/288446433

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	Difficult is sometimes OK, but it would be wrong, for example, to say ???Diamond is the most difficult rock.??? Sometimes you can use them together, as in ???difficult to get hard???, which of course always applies to concrete.
http://www.w3.org/ns/prov#wasQuotedFrom	freethoughtblogs.com