- From: Chris Welty <cawelty@gmail.com>
- Date: Sun, 07 Jun 2009 22:58:59 -0400
- To: Axel Polleres <axel.polleres@deri.org>
- CC: Jos de Bruijn <debruijn@inf.unibz.it>, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
Axel, Jos, &al, I updated SWC to be more consistent with the newer defintion of semantic multi-structures. I saw that Jos was using the bold-italic I ('''''I'''''') to denote the "common elements" of the mappings in the structures within the multi-structure (ie everything except local constants), which was kind of a shortcut to minimize the changes to SWC introduced by multi-structures, but Michael's new definition provided just such a shortcut with, conveniently, the same name ('''''I'''''') - which is the environment or context for interpreting document formulae. So I just made the text a little more consistent and removed the text that explained Jos' use of ('''''I''''''), since they are now the same. Take a look. I believe this closes the last loose end on SWC. -Chris Axel Polleres wrote: > * I am fine to keep the DL-safeness definitition "as is" for LC. > * I guess the point on the semicolon in the definition of > multistructures requires Michael Kifer's response. > > Axel > > Jos de Bruijn wrote: >> >> Axel Polleres wrote: >>> find my comments inline below. This completes ACION-830 >>> http://www.w3.org/2005/rules/wg/track/actions/830 >>> >>> Overall, I am fine with most of the changes made wrt. >>> Urgent open points: >>> >>> - DL-safeness definition. >>> >>> - Semantic multistructures and dl-multi-structures still look >>> inconsistent. >>> >>> more comments below. >>> >> >> >> My responses in-line. >> >>>>> Section 3.1 >>>>> =========== >>>>> >>>>> * Section 3.1.2 "A RIF-RDF combination consists of a RIF document and >>>>> zero or more RDFgraphs" >>>>> >>>>> Why do we allow only 1 RIF dcoument and arbitrary RDF graphs in a >>>>> combination? >>>> Because an RIF document an import any number of RDF graphs. >>> >>> >>> I am not sure whether I understand this reply, but what I >>> asked was why not several RIF documents can be involved, but ... >> >> Section 5 says how to interpret an RIF document importing a number of >> RDF graphs. There is only one RIF document involved here, and so there >> is no point to define the semantics for combinations involving more than >> one RIF document. >> >>>>> This means that simple entailment in combination with an empty >>>>> ruleset is not the same as simple entailment in RDF... I think that >>>>> should be pointed out explicitly. It would be also worthwhile to add >>>>> this example, >>>>> i.e. I suggest to add (at the end of Section 3.2.3): >>>>> "Note that simple entailment in combination with an empty ruleset is >>>>> not the same as simple entailment in RDF, since certain entailments >>>>> regarding datatypes are enforced by the RIF-BLD semantics in >>>>> combinations. For instance, given two graphs >>>>> >>>>> G1= { :s :p "foo" .} and >>>>> G2= { :s :p "foo"^^xs:string } >>>>> >>>>> as well as an empty RIF document R. >>>>> >>>>> G1 |=/=_simpleRDF G2 >>>>> following [http://link-to-rdf-mt-simple-entailment RDF simple >>>>> entailment] , but >>>>> >>>>> <R,{G1}> |=_simple <R,{G2}> >>>>> " >>>> There is already an example to this effect in the introduction to >>>> section 3. >>> >>> Then at least a pointer would be worthwhile here, so a short version >>> >>> "Note that simple entailment in combination with an empty ruleset >>> is not the same as simple entailment in RDF, since certain entailments >>> regarding datatypes are enforced by the RIF-BLD semantics in >>> combinations, cf. also Example [pointer-to-example] before." >> >> done >> >>>>> Section 4: >>>>> ========== >>>>> >>>>> >>>>> * Section 4.1.1 >>>>> "Given a set of OWL 2 DL ontologies O, a variable ?x in a RIF rule Q H >>>>> :- B is DL-safe if it occurs in an atomic formula in B that is not of >>>>> the form s[P -> o] or s[rdf:type -> A], where P or A occurs in one of >>>>> the ontologies in O." >>>>> >>>>> That doesn't seem to be sufficient, take: >>>>> >>>>> ?X [rdf:type -> d ] :- Or ( ?X [rdf:type -> c ] p(?X) ) >>>>> >>>>> this is DL-safe according to the definition above but can be expanded >>>>> to two rule one of which wouldn't be DL-safe. >>>>> >>>>> Rather, we need to adopt a safeness notion similar to Core. >>>> You are right. The definition is not sufficient. For now I just defined >>>> it for disjunction-free rules. I hope I will be able to include a >>>> proper >>>> safeness condition later on. You can also have a go at it, if you feel >>>> like it. >>> Didn't manage to tackle it either, and will likely not be able this >>> week, sorry. >> >> Do you think it is critical to have the refined definition in place >> before LC? I think it is OK to refine the definition later, since it is >> already at risk. >> >>>>> * Section 4.2.2.1 >>>>> >>>>> >>>>> * >>>>> Definition (dl-semantic multi-structure): >>>>> "I<sub>1C</sub>, ..., I<sub>1C</sub>" >>>>> >>>>> looks weird, better use 1...n as superscripts as in >>>>> http://www.w3.org/2005/rules/wiki/BLD#def-bld-semantic-multistruct >>>>> >>>>> Again, shouldn't we use \hat{I} rather than I for >>>>> multi-structures as in BLD to be consistent? >>>>> >>>>> * >>>>> same definition: >>>>> Bullet 1 ends with "and ; " >>>>> That looks incomplete, is there anything missing? >>>>> >>>>> * >>>>> "I(φ), for any other formula or symbol φ, and the truth >>>>> valuation >>>>> function TValI are defined as in BLD semantic structures. " >>>>> >>>>> I am, honestly, getting confused with the definitions of >>>>> multi-structures in BLD vs. SWC. >>>>> >>>>> dl-multistructures consist of {I_1, ..., I_n} >>>>> whereas BLD multistructures are {J,I; I_i1, I_i2, ...} >>>>> so, I am unsure what "defined as in BLD semantic structures." >>>>> means to say. >>>>> >>>>> (BTW: I sent an amendment to my BLD review per mail in this regard >>>>> as well) >>>> I updated the definition in SWC to reflect the changes in the >>>> definition >>>> in BLD. Please have a look. >>> >>> - semantic multistructures and dl-multi0-structures still look >>> inconsistent: >>> >>> section 4.2.2.1 >>> >>> >>> " >>> Formally, a dl-semantic multi-structure Î is a set of dl-semantic >>> structures {J,I, Ii1, Ii2, ...}, where " >>> >>> misses th ";" used in BLD... shouldn't this be: >>> >>> "Formally, a dl-semantic multi-structure Î is a set of dl-semantic >>> structures {J,I; Ii1, Ii2, ...}, where " >>> >>> ? >> >> To be honest, I don't understand the ';'. It is a set, and the ',' is >> commonly used to separate the individual elements in a set. >> >>> >>> - same here: >>> >>> "Given a dl-semantic multi-structure Î={I1, I2, ...}, " >>> >>> should be: >>> >>> "Given a dl-semantic multi-structure Î={{J,I; Ii1, Ii2, ...}, " >> >> It is a set of structures, so it does not really matter which symbols I >> use for the individual elements. >> >> >> Cheers, Jos >> > > -- 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
Received on Monday, 8 June 2009 02:59:51 UTC