rdf_bnode.pl -- RDF graph operations on bnodes

This module operates on RDF graphs represented as rdf(S,P,O) that contain blank nodes (bnodes). Bnodes can be considered existential variables in (sub-)graph, which motivates replacing them by Prolog variables.

 bnode_vars(+RDF, -RDFWithVars, -Vars) is det

Consistently replace bnodes in RDF with Prolog variable and unify Vars with a list of the variables found. Note that, if we perform matches with such graphs, multiple variables may unify to the same concrete resource. One might consider adding constraints such as dif/2.

Arguments:

RDF	- is a list rdf(S,P,O)
Resolved	- is a list rdf(S,P,O), where resources may be a variable
NodeIDs	- is a list of variables representing the bnodes.