- From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
- Date: Wed, 11 Jun 2003 07:54:02 +0100
- To: pat hayes <phayes@ihmc.us>
- CC: w3c-rdfcore-wg@w3.org
NO The problem of eliminating such blank nodes is plausibly NP complete. Certainly GI complete, i.e. exponential. (See related work on irredunancy of conceptual graphs [[[ Michel Chien et Marie-Laure Mugnier, Conceptual Graphs: fundamental notions in Revue d'Intelligence Atificielle, Vol 5, no 4, 1992, pp 365-406. ]] most applicable to RDFS though) Jeremy pat hayes wrote: > While fixing a silly mistake in the MT document, I noticed the > following. We require that RDF graphs contain no redundancies in the > sense that the same triple cannot occur more than once in the graph. > However, they can contain redundancies in the sense that a triple with a > bnode in it can be duplicated with a different bnode, even though the > resulting triples would look the same in a graph diagram. The resulting > graph has no extra information in it, but this quirk allows an RDF graph > to have infinitely many consequences. For example, a single triple > > a p b . > > has infinitely many consequences; > > _:x p b . > a p _:y . > _:z1 p _:z2 . > _:z3 p _:z4 . > -:z5 p _:z6 . > .... > > where all these bnodes are distinct; see attached jpeg. > > My question is, does the WG feel that it might be worth ruling this out > as a syntactic possibility? If this kind of bnode-duplication were ruled > out, then the set of graphs simply entailed by any RDF graph would be > finite. That would generalize the no-duplicate-triples condition > implicit in our definition of a graph as a set, to treat triples which > 'look' the same when you erase the bnode labels as though they literally > were the same. > > Pat > >
Received on Wednesday, 11 June 2003 02:54:17 UTC