- From: Frank Manola <fmanola@mitre.org>
- Date: Thu, 28 Jun 2001 17:00:46 -0400
- To: Dan Connolly <connolly@w3.org>
- CC: pat hayes <phayes@ai.uwf.edu>, w3c-rdfcore-wg@w3.org
Dan Connolly wrote: > snip > A prolog query > author(X, "b"), title(X, "f e") > is a request to prove the theorem > > (exists (?x) (author ?x "b") (title ?x "f e)) > right? and the query results are proofs; i.e. substitutions > of the variables that show that it's satisfyable. > > That's how queries work, right? They're existential formulas, > and the job of a query engine is to give proofs, by > example, of the theorem. This is completely traditional, no? > > [[[ > Free variables in a query > are assumed to be existentially quantified. > ]]] > > -- Knowledge Interchange Format > http://logic.stanford.edu/kif/dpans.html > Thu, 25 Jun 1998 22:31:37 GMT Sorry if this appears to be barging in out of the blue, but the KIF spec you cited says: * Note that the significance of free variables in quantifier-free sentences depends on context. * Free variables in an assertion are assumed to be universally quantified. Free variables in a * query are assumed to be existentially quantified. In other words, the meaning of free variables * is determined by the way in which KIF is used. It cannot be unambiguously defined within KIF itself. * To be certain of the usage in all contexts, use explicit quantifiers Based on this, it seems to me that we'd need to say more than that we're interpreting anonymous resources as free variables. We'd also need to say whether we're expressing an assertion or a query. So far, I thought we'd been assuming that RDF was making assertions. On the other hand, it might be that RDF is in the same position as KIF is here, and we'd need to take context into consideration. --Frank -- Frank Manola The MITRE Corporation 202 Burlington Road, MS A345 Bedford, MA 01730-1420 mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-8752
Received on Thursday, 28 June 2001 17:01:18 UTC