- From: Jos de Bruijn <jos.debruijn@gmail.com>
- Date: Thu, 18 Mar 2010 17:01:38 +0100
- To: Axel Polleres <axel.polleres@deri.org>
- CC: Chris Welty <cawelty@gmail.com>, RIF <public-rif-wg@w3.org>, Ivan Herman <ivan@w3.org>, Birte Glimm <birte.glimm@comlab.ox.ac.uk>, Chimezie Ogbuji <ogbujic@ccf.org>, Sandro Hawke <sandro@w3.org>
I see what you mean. An implementation that does not take one of the imports into account does not follow the spec. Now, concerning the rif:imports. Could you explain me again why it is a good idea to extend the RDF semantics to include RIF-RDF combinations? I understand that you want to use SPARQL to query RIF-RDF combinations. How does the syntactic construct in RDF help? Why not have implicit rulesets (like the implicit datasets) and give the user the possibility to refer to a RIF ruleset from the query? Jos On 2010-03-18 11:18, Axel Polleres wrote: >> I'm not sure what you mean with the imports mechanism having a >> semantics. The semantics of the combination (R2,G) is clearly defined in >> the SWC spec. > > Yes it is clearly defined, and it wouldn't take the import of R1 from G > into account. So, in case we define a semantics for importing rulesets > from graphs, an implementation that takes this imports-mechanism into > account will not be compatible to the SWC spec on this example. > > Axel > > On 18 Mar 2010, at 10:10, Jos de Bruijn wrote: > >> >> >> On 2010-03-12 15:32, Axel Polleres wrote: >>> On 12 Mar 2010, at 14:09, Chris Welty wrote: >>>> Axel, >>>> >>>> I really really really do not understand why it matters whether RIF specifies this or SPARQL. >>>> RIF should be viewed as read-only right now unless there is an error. >>> >>> 1) the *main issue* is the URI we use for dereferencing, which we think should be in the rif: namespace, i.e. we need >>> rif:'s blessing if we do so. >>> >>> >>> I mentioned in the mail already that it would probably be an alternative if we could just produce a (joint?) >>> note or separate (rec?) document on this. That would mean we wouldn't touch the rif-rdf-owl spec as such. However ... >>> >>> 2) ... as I see it there is *potential issue* around a separate spec which worries me a lot... >>> if we *don't* specify the importing from RDF within rif-rdf-owl, then whatever we write in that note separate spec >>> would be potentially incompatible with rif-rdf-owl ... here's why: >>> >>> Say you have two rulesets R1, R2 and one graph G: >>> >>> G: >>> G <> rif:imports [rif:ruleset R1 rif:profile <...simple...> ]. >>> >>> R2: >>> Imports( G <...simple...> ) >>> ... some rules ... >>> >>> R1: >>> (Imports R2) >>> ... some other rules ... no imports clause >>> >>> Now... depending on whether or not the imports-mechanism in RDF has a semantics, the RIF-RDF combination (R2,G) >>> has different semantics. >> >> I'm not sure what you mean with the imports mechanism having a >> semantics. The semantics of the combination (R2,G) is clearly defined in >> the SWC spec. >> >> >> Cheers, Jos >> >>> >>> So, my worry is, if we postpone that issue to post-RIF, we can't define it in an upwards compatible way at all... >>> besides, I think it is a very minor change, which makes live much easier for applications coming from the RDF side >>> doing something with RIF and doesn't seem to affect 99% of those caring from the RIF side only. >>> >>> Axel >>> >>> >>>> -Chris >>>> >>>> Axel Polleres wrote: >>>>> Hi all, >>>>> >>>>> We had the topic of "rif:imports" coming up in SPARQL again in our Entailment regimes taskforce call this week. >>>>> >>>>> The reason why we (from the SPARQL side) would prefer to have that imports mechanism defined in RIF, >>>>> is mainly that we think that the URIs to use for defining this imports mechanism should be in the rif: >>>>> namespace, since this imports mechanism is likely useful not only for SPARQL but also for other >>>>> RDF applications that wnat to interact with RIF. >>>>> >>>>> Thus, I wanted to inquire again, whether we'd have a chance to get that an import mechanism for RIF from RDF into >>>>> http://www.w3.org/TR/rif-rdf-owl/ ? >>>>> >>>>> If the group overall still thinks that it is too late to get this into the spec, in turn, I wanted to ask/raise >>>>> again how/whether we could proceed to publish this text as a WG Note? >>>>> >>>>> I have earlier made a simple proposal to add a new section to the current spec, which we elaborated a bit now: >>>>> >>>>> 1) In the introduction of http://www.w3.org/2005/rules/wiki/SWC, >>>>> I would suggest to add: >>>>> >>>>> "RDF Graphs in RIF-RDF-combinations are assumed to not contain any triples using the predicates >>>>> rif:imports, rif:ruleset and rif:profile we refer to Section 6 for treatment of such graphs. >>>>> " >>>>> >>>>> 2) Further, I would suggest to add a new section: >>>>> ==================================================================================== >>>>> >>>>> = 6 Importing RIF rulesets in RDF = >>>>> >>>>> The definitions so far, only covered RIF-RDF-combinations where the RDF graphs did not contain >>>>> triples using rif:usingRuleset in predicate positions. To lift this restriction, we define >>>>> RIF-X-combinations (R,S) where any of the graphs in S contains triples with the predicates >>>>> rif:imports, rif:ruleset and rif:profile >>>>> by a reduction to combbinations without such triples as follows. >>>>> >>>>> Let (R, S) be a combination as above. The reduction of R is defined as the >>>>> RIF-X-combinations (R', S') where >>>>> (i) S' is identical to S with all rif:imports, rif:ruleset and rif:profile triples removed, >>>>> and >>>>> (ii) R' is identical to the RIF document R, >>>>> with the addition that R' has additional imports clauses >>>>> Imports( R1 ) >>>>> Imports( G P ) >>>>> for any triples >>>>> >>>>> <> rif:imports [rif:ruleset R rif:profile P ]. >>>>> >>>>> in (simple entailed by) S, such that R1 is an IRI referring to a RIF document and >>>>> P is a URI referring to an imports profile as defined in >>>>> Section http://www.w3.org/2005/rules/wiki/SWC#Profiles_of_Imports >>>>> >>>>> Together with the conditions in section 5.2 this ensures that RIF-X-combinations where R is empty, i.e. which >>>>> are only defined by a set of RDF graphs, can also import RIF rulesets. >>>>> >>>>> ==================================================================================== >>>>> >>>>> In case there is a chance to get this on one of the next agendas, please let me know, since I have recently not >>>>> really had time to be follow the RIF TCs, but I'd be joining for that. >>>>> >>>>> best, >>>>> Axel >>>>> >>>>> P.S.: Condition (i) which removes all the rif:usingruleSet triples, i.e., >>>>> just treats these triples as a directive rather than part of the graph, may be dropped, i.e. simply >>>>> keeping S as is, accepting the rif:imports, rif:ruleset and rif:profile triples as part of the graph. >>>>> >>>> >>>> -- >>>> Dr. Christopher A. Welty IBM Watson Research Center >>>> +1.914.784.7055 19 Skyline Dr. >>>> cawelty@gmail.com Hawthorne, NY 10532 >>>> http://www.research.ibm.com/people/w/welty >>>> >>> >>> >> >> -- >> Jos de Bruijn >> Web: http://www.debruijn.net/ >> LinkedIn: http://it.linkedin.com/in/josdebruijn >> Skype: josdebruijn >> Google Talk: jos.debruijn@gmail.com >> Mobile phone: +43 660 313 5733 >> > -- Jos de Bruijn Web: http://www.debruijn.net/ LinkedIn: http://it.linkedin.com/in/josdebruijn Skype: josdebruijn Google Talk: jos.debruijn@gmail.com Mobile phone: +43 660 313 5733
Received on Thursday, 18 March 2010 16:02:13 UTC