From: Stefan Decker (stefan@db.stanford.edu)
Date: 05/31/01
Pat, >Im afraid I disagree. In fact, this remark sounds to me to simply be >nonsensical. What do you mean by 'treating a tuple in a logical way' if >the tuple has no known relationship to any kind of logical meaning? Only taking herbrand models into account an atom triple(s,p,o) (syntax) corresponds to tuple <s',p',o'> \in triple' (semantics). Thats enough of logical meaning necessary to do something useful with rules on triples. Do you disagree? If yes, please specify what else you need. >I meant musical key shifts, as for example when transposing from C to B >flat. I think you would have trouble doing that in Prolog with the musical >notation I sketched above. I would have trouble doing that in any programming language since I don't know enough about musical transposition. >I don't think that makes sense, but in any case that is not what I am >trying to do, or think that DAML should be trying to do. > >>However, can be go back to the topic of designing a useful rule language? >>It seems to me that the difference between: >> 1) "RDF is a datastructuing language and tripels should not be >> interpreted as facts" and >> 2) "RDF tripels are facts" >>is more than esoteric. It seems obvious that triples can be regarded as >>atoms in a logical language, >>at least if I not misunderstood your proposal (see >>http://www.daml.org/listarchive/joint-committee/0436.html) >>that was also your suggestion. > >They can be, indeed, and I would like to continue to so regard them. >However, to my mind that it is incompatible with denying that they have a >semantics, or trying to write rules that ignore the semantics. I still >cannot understand quite how you manage to reconcile these positions. > >>Can we please focus more on designing a useful rule language? > >We got into this discussion because with our different notions of what a >rule language is, we seem to have different notions of what 'useful' >means. I emphatically do not see DAML rules as intended to provide >arbitrary open-ended programming functionality. Me neither. We can discuss what features we see essential for a rule language, and probably will come up with a classification of different languages, each one with a different purpose. My minimal requirements for a horn logic based language: 1) The rule language should to able to XXXX RDF ( choose XXXX from { process, transform, reason with, .... ) 2) The rule language should support different RDF vocabularies (this will get more concrete once we reach agreement that we want to have more than just a fixed vocabulary ). 3) The rule language should be able to distinguish between different RDF data sources (data is distributed and has different properties). More requirements I would argue for ------------------------------------------------------------------------------------- 4) Closed World Reasoning (test if a triple is in a given RDF model or not) (requires a suitable semantics for negation - well founded semantics is suggested for various reasons). 5) At least syntactically as expressive and convenient as possible (e.g. FOL-bodies in rules) What are your concrete requirements? All the best, Stefan >Pat > >--------------------------------------------------------------------- >IHMC (850)434 8903 home >40 South Alcaniz St. (850)202 4416 office >Pensacola, FL 32501 (850)202 4440 fax >phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
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