- From: Pan, Dr Jeff Z. <jeff.z.pan@abdn.ac.uk>
- Date: Thu, 28 Apr 2011 14:01:39 +0100
- To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
- CC: "Zhao, Yuting" <yuting.zhao@abdn.ac.uk>, SPARQL Working Group <public-rdf-dawg@w3.org>
Hi Birte, Yes, it does. Many thanks, Jeff On 28/04/2011 12:48, "Birte Glimm" <birte.glimm@comlab.ox.ac.uk> wrote: >Jeff, Yuting, >I added now two diagrams along the lines of what you suggested. Since >I am already in the middle of the publication process for last call. I >don't want to upload the changed .xml version, which is linked from >our wiki as it says already "This document is a Last Call Working >Draft". You can, however, see the changes in: >http://www.w3.org/2009/sparql/docs/entailment/gen.html >Does that address you comment? >Cheers, >Birte > >On 27 April 2011 18:27, Birte Glimm <birte.glimm@comlab.ox.ac.uk> wrote: >> Hi Jeff and Yuting, >> thanks for the clarification. The example diagrams make it clear what >> you are looking for. I'll check how I can incorporate the files. >> Best regards, >> Birte >> >> On 27 April 2011 17:06, Pan, Dr Jeff Z. <jeff.z.pan@abdn.ac.uk> wrote: >>> Hi Birte, >>> >>> We are happy to see these changes addressing most of our comments. >>> >>> As for the suggestion of adding diagrams, we simply think it is an >>>option >>> to improve the readability of this document. >>> >>> Attached are some sample diagrams. Diagram1.2.jpg is for [1.2 Effects >>>of >>> Different Entailment Regimes], which visualizes the 3 patterns. >>> diagram2.1.jpg is for [2.1 Blank Nodes in the Queried Graph], in which >>>the >>> reader could immediately indentify G3 having a different pattern from >>>G, >>> and understand why G3 is a problem for the query. >>> >>> Many thanks, >>> >>> Jeff and Yuting >>> >>> >>> >>> On 27/04/2011 10:34, "Birte Glimm" <birte.glimm@comlab.ox.ac.uk> wrote: >>> >>>>Jeff, Yuting, >>>>since I haven't heard from you, I assume that my changes addressed >>>>your comments. Please let me know ASAP if that is not the case. >>>>Regards, >>>>Birte >>>> >>>> >>>>On 19 April 2011 15:02, Birte Glimm <birte.glimm@comlab.ox.ac.uk> >>>>wrote: >>>>> Jeff, Yuting, >>>>> could you give me some feedback on the questions I had for your >>>>>review? >>>>>Thanks, >>>>> Birte >>>>> >>>>> On 5 April 2011 13:35, Birte Glimm <birte.glimm@comlab.ox.ac.uk> >>>>>wrote: >>>>>> Jeff, Yuting, >>>>>> many thanks for the review in particular given the very short >>>>>>notice. >>>>>> I comment inline below. >>>>>> Birte >>>>>> >>>>>> On 5 April 2011 07:16, Pan, Dr Jeff Z. <jeff.z.pan@abdn.ac.uk> >>>>>>wrote: >>>>>>> Overall: Due to very short notice, we were only able to give a >>>>>>>brief >>>>>>> review. In short, the specification has good quality in general and >>>>>>>still >>>>>>> has room for improving its presentation: >>>>>>> >>>>>>> Abstract: >>>>>>> >>>>>>> "SPARQL is a query language ©": shouldn't SPARQL be both a query >>>>>>>language >>>>>>> and a protocol? >>>>>> >>>>>> True. I changed it to "SPARQL is a query language and a protocol >>>>>>for..." >>>>>> >>>>>>> "It is desirable to utilize SPARQL as a query language in these >>>>>>>cases >>>>>>>©": >>>>>>> given the importance of RDF and OWL in the Semantic Web, we >>>>>>>propose to >>>>>>> replace "desirable" to "necessary". >>>>>> >>>>>> My understanding is that the much stronger term "necessary" might be >>>>>> considered too strong for many who don't think that querying for >>>>>> inferred statements is necessary. How about relativising this for >>>>>>the >>>>>> application's requirements. Below is my suggestion including the >>>>>> preceeding sentence to give the context: >>>>>> >>>>>> "Various W3C standards, including RDF and OWL, provide semantic >>>>>> interpretations for RDF graphs that allow additional RDF statements >>>>>>to >>>>>> be inferred from explicitly given assertions. Many applications that >>>>>> rely on these semantics require a query language such as SPARQL, but >>>>>> in order to use SPARQL basic graph pattern matching has to be >>>>>>defined >>>>>> using semantic entailment relations instead of explicitly given >>>>>>graph >>>>>> structures. " >>>>>> >>>>>> >>>>>>> "© standard entailment relations in the semantic web such as RDF >>>>>>> entailment, RDFS entailment, etc. are defined in this document": >>>>>>>Are >>>>>>>the >>>>>>> definitions different from those in the RDF and OWL specifications? >>>>>>>If so, >>>>>>> we need to summarise the differences somewhere in this >>>>>>>specification. >>>>>> >>>>>> The full sentence is >>>>>> "Such extensions of the SPARQL semantics are called entailment >>>>>>regimes >>>>>> within this document and entailment regimes for standard entailment >>>>>> relations in the semantic web such as RDF entailment, RDFS >>>>>>entailment, >>>>>> etc. are defined in this document. " >>>>>> >>>>>> An entailment regime says not only which entailment relation is to >>>>>>be >>>>>> used, but also specifies what queries and graphs are well-formed, >>>>>>how >>>>>> inconsistencies are handled etc. The docuement defines entailment >>>>>> regimes *for* standard entailment relations, i.e., the entailment >>>>>> relaions themselves are unchanged, but also well-formedness for >>>>>>graphs >>>>>> and queries etc. >>>>>> >>>>>> To clarify this, I changed the sentence to: >>>>>> >>>>>> "An entailment regime defines not only which entailment relation is >>>>>> used, but also which queries and graphs are well-formed for the >>>>>>regime >>>>>> or what kinds of errors can arise. The entailment relations used in >>>>>> this document are standard entailment relations in the semantic web >>>>>> such as RDF entailment, RDFS entailment, etc." >>>>>> >>>>>> >>>>>>> Inconsistent graph: >>>>>>> >>>>>>> Inconsistency is not defined formally in the specification. The >>>>>>>terms >>>>>>> "inconsistency" and "inconsistent graph" are first used in Sec 1.3, >>>>>>>without >>>>>>> formal definitions. >>>>>> >>>>>> The first section is introdutory and does not aim at defining >>>>>> anything. The concrete regimes do link to the relevant definitions, >>>>>> e.g., in the RDFS Entailment regime RDFS-inconsistent is linked to >>>>>>the >>>>>> relevant section from the RDF Semantics spec, which also defines the >>>>>> RDFS semantics incl. RDFS-inconsistent graphs. >>>>>> >>>>>> I now say in Section 1.3, which introduces the general idea of BGP >>>>>> matching extensions and the issues that any ent. regime has to >>>>>> address: >>>>>> An inconsistent graph is one for which no interpretation exists that >>>>>> satisfies all conditions of the semantics that is used. The issue is >>>>>> discussed in more detail in <link>Section 3.1</link>, which also >>>>>> provides an example for an RDFS-inconsistent graph. Since >>>>>>inconsistent >>>>>> graphs entail any triple, special care has to be taken to to adress >>>>>> the situation. The effect of a query on an inconsistent graph is >>>>>> covered by the particular entailment regimes and, for each regime, >>>>>>the >>>>>> relevant details can be found in the corresponding section for that >>>>>> entailment regime. >>>>>> >>>>>> How exactly an inconsistent graph is defined depends on the >>>>>>semantics >>>>>> that is used and can, therefore, not be defined in an overview that >>>>>> discusses the general issues that all regimes have to adress. >>>>>>However, >>>>>> any E-inconsistent graph (for E some semantics such as RDFS or OWL >>>>>> Direct Semantics) has the same problem, i.e., any triple is >>>>>>entailed. >>>>>> >>>>>>> Due to the nature of the Web, the handling of inconsistent graph >>>>>>>is a >>>>>>>key >>>>>>> issue in this specification. It might be useful for readers if a >>>>>>>future >>>>>>> version of this specification includes a sub-section as a single >>>>>>>entrance >>>>>>> point on inconsistent graphs. >>>>>> >>>>>> This is now discussed per entailment regime, i.e., each table that >>>>>> defines a regime has an entry that defines how inconsistencies are >>>>>> handled. In addition, the issue is discussed in informal sections >>>>>> where relevant new issues arise, e.g., since the RDFS ent. regime is >>>>>> the first where inconsistencies can arise, Section 3.1 discusses >>>>>>that >>>>>> in quite some detail. Also note that the OWL ent. regimes require >>>>>> inconsistency checking as it is typically done by OWL reasoners, >>>>>> whereas the RDFS and D-Entailment regimes only require that a >>>>>>warning >>>>>> is generated if the quey processor detects the inconsistency. The >>>>>>RDF >>>>>> on the other hand is not powerful enough to state inconsistencies. >>>>>> Thus, a per regime discussion seems to me the only real option. >>>>>> Splitting Section 1.3 into two seems quite difficult to me since >>>>>>also >>>>>> SPARQL Query, which defines the conditions on BGP matching >>>>>>extensions, >>>>>> discusses all issues in one section. >>>>>> >>>>>>> Diagrams: some diagrams might be useful to illustrate some abstract >>>>>>>ideas in >>>>>>> the following sections: >>>>>>> >>>>>>> 1.2 Effects of Different Entailment Regimes >>>>>>> 2.1 Blank Nodes in the Queried Graph >>>>>> >>>>>> It is not clear to me what kind of diagrams you suggest. Could you >>>>>> describe in more detail what you would expect to see in such a >>>>>> diagram? >>>>>> >>>>>>> Greetings, >>>>>>> Jeff Pan and Yuting Zhao >>>>>>> >>>>>>> The University of Aberdeen is a charity registered in Scotland, No >>>>>>>SC013683. >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Dr. Birte Glimm, Room 309 >>>>>> Computing Laboratory >>>>>> Parks Road >>>>>> Oxford >>>>>> OX1 3QD >>>>>> United Kingdom >>>>>> +44 (0)1865 283520 >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Dr. Birte Glimm, Room 309 >>>>> Computing Laboratory >>>>> Parks Road >>>>> Oxford >>>>> OX1 3QD >>>>> United Kingdom >>>>> +44 (0)1865 283520 >>>>> >>>> >>>> >>>> >>>>-- >>>>Dr. Birte Glimm, Room 309 >>>>Computing Laboratory >>>>Parks Road >>>>Oxford >>>>OX1 3QD >>>>United Kingdom >>>>+44 (0)1865 283520 >>> >>> >>> >>> The University of Aberdeen is a charity registered in Scotland, No >>>SC013683. >>> >> >> >> >> -- >> Dr. Birte Glimm, Room 309 >> Computing Laboratory >> Parks Road >> Oxford >> OX1 3QD >> United Kingdom >> +44 (0)1865 283520 >> > > > >-- >Dr. Birte Glimm, Room 309 >Computing Laboratory >Parks Road >Oxford >OX1 3QD >United Kingdom >+44 (0)1865 283520 The University of Aberdeen is a charity registered in Scotland, No SC013683.
Received on Thursday, 28 April 2011 13:02:14 UTC