- From: Jim Hendler <hendler@cs.umd.edu>
- Date: Tue, 8 Jun 2004 08:51:15 -0400
- To: "Seaborne, Andy" <andy.seaborne@hp.com>, public-rdf-dawg@w3.org
Andy- I think you missed the intent of my message - I tried to be clear that I was NOT talking about an open ended query -- I would not be going to CYC and saying tell me what you know about cats, I would be going to a graph and querying forthe bindings for a query something like this (I leave it in RDF/XML form for readability, but the quesry would be for those subgraphs of triples that match this <owl:class rdf:resource=":cat"> <?CLASSTYPE> <owl:Restriction> <owl:onProperty ?PROP/> <?OWL ?REST> </owl:Restriction> </rdfs:subClassOf> </owl:class> i.e. I don't say "tell me about cats" - I say Query the CYC graph for the pattern in which cat has a CLASSTYPE (subclassof or equivalentClass) of a restriction class and return to me the names of what PROPerties the restriction is on, what OWLterm the restriction uses (AllValues, SomeValues, etc.) and what the RESTriction is. In practice I might do something different than this (perhaps multiple queries for specific combinations as I needed them), but in every case I am asking for specific properties of specific entities from an RDF graph - in my opinion, this capability is why I devoted so much of my past few years to making OWL an RDF language -- if I just wanted to query documents, I would have agreed that an XML syntax was sufficient -- but for linking and processing OWL, I want to use the URIs and the graph As far as 3.6 v. 3.7 goes, I was thinking of 3.7 for a couple of reasons: first, when cardinality is used the syntax of the query has to be able to handle the fact that the cardinalities are expressed using xsd:nonNegativeIntegers, and also some of the restrictions in OWL for datatype properties would include being able to query for the datatype -- maybe I was misinterpreting what 3.7 was intended for. As far as 3.6 goes, I guess I could use optional features in the above, I was thinking of multiple queries myself, but could go either way ... Hope that helps make things clearer -- if you want me to work out the informal example above as the actual triples, I'd be happy to, just didn't have the time so far. -JH At 10:32 +0100 6/8/04, Seaborne, Andy wrote: >-------- Original Message -------- >> From: Jim Hendler <> >> Date: 7 June 2004 17:57 >> >> I'm not sure if this is a WD comment from an outsider (since I wasn't >> a member when the WD went out) or a suggestion from a new member (as >> I now am on the DAWG), but I would like to suggest that we add >> another use case to the document. I think it is an important class >> of query that was completely ignored in the current draft (esp. as >> FOAF is rapidly becoming one of the most used Sem Web things, and >> this would refer to it). >> >> In processing an RDFS schema or an OWL ontology that cites a term in >> another ontology, c.f. >> me:Lilah a cyc:cat, >> I want to know what restrictions the cited graph has for this class >> -- i.e. in this example, I want to ask >> cyc: for those triples of the form where the class definition >> includes a restriction (I'll spare you the gory details now, easy to >> generate) so I can process the triples appropriately, etc. > >It seems to me that the underlying requirement is to be able to ask cyc: for >what it knows about this class. It is a general, open question "tell me >about cyc:cat" or possibly "tell me about cyc:cat because I want to process >it" (that is, setting some context to the query). The significant point is >that the client can't know exactly the graph pattern. Here, there may be >several restrictions for the class. > >We had queries of this kind in early email: it's a data oriented task but I >think has this similar characteristic of being an open "tell me about" >question. > >http://lists.w3.org/Archives/Public/public-rdf-dawg/2004JanMar/0022.html > >where the query is "tell me about" addressed to different KBs, resulting in >different information. In each case, the query is an open question to the >KB and the requestor is then going to look at the graph returned (it has to >be a graph - not variable bindings). > >Jim - have I understood you correctly? > >This has got a bit lost in the document IMHO. The nearest I can see is the >2.2 "Finding Information about Motorcycle Parts (Supply Chain Management)" >where the query gets back "Accelerator Cable" depends-on "Mounting Bracket" >and requires some screws. This isn't an exact graph pattern match - it's a >"tell me about "Accelerator Cable" which also yields other stuff that the >server has been configured to return. > >This "tell me about" query does not get reflected into the requirements >except weakly in 3.4 (Subgraph Results). I see it as important though for >semantic web applications which want to do some further processing, here >process classes and properties, or wish to aggregate information from >different places and pass the assembled RDF graph to some other system. > >(Aside: the text says "fuel management system" but the example is >"Accelerator Cable MK3" and "Mounting Bracket"). > >> >> >> I think it would be a valuable use case to publish as it is quite >> likely to come up quite often as, for example, FOAF and the like >> take-off, and people want to be able to process new data (i.e. go to >> the schema, see whether the new property "foaf:dnaCheckSum" we >> haven't seen before is inverse-functional) - I should note that I >> assume that the serialized graph of a number of important ontologies >> and schemas will be available on the Semantic Web (it is already >> happening for a number of them) and thus doing this by query of an >> RDF graph, rather than HTTP-GET of the document (which could be very >> large - the NCI ontology document, for example, is >25M) will be much >> more efficient. >> >> I believe it will be easy to make this a use case in the form the >> UC&R document uses (something like: A social network site is >> processing people's data based on foaf data that was dumped from a >> different social networking site. It encounters a property it has >> not previously encountered so it queries a schema server to see >> whether this property has restrictions that would effect later >> processing of the data ...) >> >> I don't think this new use case would add any requirements or >> objectives, however I do think it makes a strong case for some of the >> existing ones (3.1, 3.4, 3.7, 4.2, 4.3) and is also an important one >> in that it helps to demonstrate that the DAWG's work is important for >> RDFS and OWL, not just RDF DBs. >> >> -Jim H. > >I don't see the relationship to 3.7 (Limited Datatype Support) but I do see >the relationship to 3.6 (Optional Match). > > Andy -- Professor James Hendler http://www.cs.umd.edu/users/hendler Director, Semantic Web and Agent Technologies 301-405-2696 Maryland Information and Network Dynamics Lab. 301-405-6707 (Fax) Univ of Maryland, College Park, MD 20742 240-277-3388 (Cell)
Received on Tuesday, 8 June 2004 08:51:34 UTC