- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Tue, 01 Oct 2002 16:48:05 +0100
- To: Sergey Melnik <melnik@db.stanford.edu>
- Cc: w3c-rdfcore-wg@w3.org
At 10:24 AM 10/1/02 +0200, Sergey Melnik wrote: >Our problem is that the entailment capability is *not* part of RDF >spec. If it were, then we could define formally what the result of >entailment should be, applied to graphs. However, we do not require each >and every RDF application to support entailment (thanks God). Entailment *capability* may not be part of the RDF spec, but certain allowable entailments *are*. The fact that RDF permits certain entailments is not the same as saying RDF requires applications to deliver those entailments. >Recall that entailment is a syntactic procedure, more precisely, a binary >relation that holds between syntactic sentences (graphs, in our case). ?!? I thought entailment was precisely a *semantic* relation, defined in terms of truth of expressions (graphs) (which I grant are syntactic entities) under any interpretation. >Defining entailment (in terms of logical inference) is comparable to >defining the semantics of a query language, like SQL. At this point of >time, we do not force every RDF application to support a specific query >language (which we could use to test tidiness)... "Defining entailment (in terms of logical inference)" sounds line an oxymoron to me. But I agree that we don't require all applications to find all valid entailments. In fact, I don't think we require applications to do anything (though it is sometimes convenient to describe aspects of RDF by characterizing our expectations of applications -- I thought the whole idea of the formal semantics was to be able to nail down RDF meaning without having to describe applications). #g ------------------- Graham Klyne <GK@NineByNine.org>
Received on Tuesday, 1 October 2002 15:06:35 UTC