rdf11:rdf_reachable/3

rdf_reachable(?S, +P, ?O) is nondet
rdf_reachable(?S, +P, ?O, +MaxD, -D) is nondet: True when O can be reached from S using the transitive closure of P. The predicate uses (the internals of) rdf_has/3 and thus matches both rdfs:subPropertyOf and the inverse_of and symmetric predicate properties. The version rdf_reachable/5 maximizes the steps considered and returns the number of steps taken.
If both S and O are given, these predicates are semidet. The number of steps D is minimal because the implementation uses breadth first search.