- From: Jeff Heflin <heflin@cse.lehigh.edu>
- Date: Wed, 08 May 2002 14:49:26 -0400
- To: Pat Hayes <phayes@ai.uwf.edu>
- CC: www-rdf-logic@w3.org
Sure, your reasoner is free to ignore anything it wants, but then it cannot claim to be a complete reasoner. Otherwise, I'd claim that my MS Access database is a complete reasoner for first-order logic. I just choose to ignore anything that's not a ground atom. ;-) I am saying the daml:imports has semantic import (no pun intended) for the language. A complete reasoner must include the axioms from all imported documents. Finally, let me respond to your "dream world" comment, point-by-point. 1) Subsitute the word axiom everywhere I've used definition in this discussion. The axioms that use a term help to "define" that term, although it is well known that it is impossible to logically define many terms. 2) An ontology cannot restrain the actions of an inference engine, but a sound and complete inference engine must obey the semantics of the ontology. 3) This discussion is intended to help build a Semantic Web that isn't just a dream world. I think those who believe that we can simply assume no one will disagree and that we can make one big consistent Web knowledge base are the ones living in the dream world. daml:imports build on ideas used in other ontological systems, although admittedly formal definitions of the semantics of such constructs are few and far between. Sure, daml:imports won't solve our inconsistency problems, but at least it will allow people to direct reasoners to sets of ontologies they believe are mutually consistent. I think this is a big and important step in the right direction. Jeff Pat Hayes wrote: > > > > >> If it is applied to a document as in b) do all DAML+OIL resources > >> referenced within that document also use the imported ontology? Or > >> just to statements about the document itself? > > > >In terms of merging RDF graphs, daml:imports means you can't add that > >triples from some graph unless you also add all the triples from the > >graphs of the resources that are imported. > > But wait a minute. What does it even mean for your ontology to say > what my reasoning engine can or cannot do? Of course I CAN add > triples from one graph without adding triples from another. All that > any ontology can do is to express some propositional content. What > another engine does with that content can be reasonably expected to > conform to the semantics of the language, but that's about all. If > the engine decides to ignore some of what you say, that's it's > business, not yours. Ignoring part of any RDF graph is perfectly > valid considered as an inference, after all: an RDF graph entails all > its subgraphs. > > I think this entire discussion is in a dream world. First, there are > no clear notions of definition to appeal to. Second, no ontology can > restrain the actions of a remote inference engine. Third, why would > one want things to be different? > > 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
Received on Wednesday, 8 May 2002 14:49:29 UTC