- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Fri, 14 Sep 2012 10:33:02 -0400
- To: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- CC: RDF WG <public-rdf-wg@w3.org>
On 09/14/2012 09:26 AM, Antoine Zimmermann wrote: > > > Le 13/09/2012 20:13, Peter F. Patel-Schneider a écrit : >> >> On 09/13/2012 12:50 PM, Antoine Zimmermann wrote: >>> Le 13/09/2012 03:08, Peter F. Patel-Schneider a écrit : >>> >> [...] >> >>>> >>>> It is also the case that an inconsistent default graph makes the named >>>> graphs irrelevant. >>> >>> It makes the dataset inconsistent, which is fortunate. >> >> I don't consider this to be particularly fortunate. Why should an >> inconsistent default graph make the named graphs irrelevant? Why should >> the default graph situation bleed into the named graphs at all? > > This semantics consider that datasets are sentences and quotes of sentences > (not quote in the sense of Sandro's "quoting semantics, but in the usual > conversation sense). For instance, consider the following statements: > > Joe is a person. Joe is not a person. Joe told me "I am person". > > This is inconsistent. However: > > Joe is a person. Joe told "I am a person and I am not a person". > > This is consistent. What Joe says is inconsistent, but it's irrelevant for > the consistency of my statements. > This is a particular view of how RDF datasets should work. I don't subscribe to this view. > >>>> This last is, I think, a particularly strong point against providing >>>> this sort of semantics at all. >>> >>> By "this last", what do you mean? This last test case (T14.1) or this >>> last sentence that you wrote above? >>> >>> I think you mean the former (if it's the latter, I don't see why). Do >>> you think that, if the graphs--named and default--were independent, it >>> would be acceptable? That's the alternative proposal where IGEXT maps >>> IRIs to graphs, instead of resources to graphs. >> >> I prefer having the named graphs independent of each other, and >> independent of the default graph. I might be able to live with the >> situation where an inconsistent default graph makes the named graphs >> irrelevant, but why should I have to? We could just go back to the >> proposals from much earlier where these sorts of issues do not arise. > > Which proposals? > Here are some documents/messages with proposals. http://www.w3.org/2011/rdf-wg/wiki/images/3/3b/Rdfwg-graphs-tf-report.pdf slide 5 proposal (a), although I can't find a separate source for the proposal itself http://lists.w3.org/Archives/Public/public-rdf-wg/2012Mar/0041.html proposes a simpler semantics, which I prefer over the more complex one, but I prefer something even simpler http://lists.w3.org/Archives/Public/public-rdf-wg/2012Apr/0188.html http://lists.w3.org/Archives/Public/public-rdf-wg/2012Aug/0030.html the suggestion near the bottom of the message >> >> peter >> >> PS: Here is a reiteration of the old proposals. >> >> There is no independent notion of interpretations of RDF datasets. If >> you want to do something like entailment between RDF datasets you can >> either look at one component of the dataset, so you ask whether the >> default graphs sit in an entailment relationship or ask whether the >> graphs with a particular name sit in an entailment relationship, or you >> can look at the entire dataset, so you ask whether the default graphs >> sit in an entailment relationship and all the similarly-named graphs sit >> in an entailment relationship. In each case you probably want to >> consider a missing named graph to be the empty graph. This ends up being >> more flexible and considerably simpler than the minimal semantics >> currently being proposed, as well as requiring no new reasoning machinery. >> > > > To me, it is important to have entailment between datasets. > > { <n,G> } entails { <n,G'> } > > is not the same as "extract G from <n,G>, G entails G'". > > I want that the inferred triples are labeled by the graph IRI, for various > purposes including version management, provenance management, temporal > validity, etc. > I don't see what you get from this beyond entailment between RDF graphs. If, however, the WG ends up with some definition of entailment between RDF datasets, I much prefer a direct relationship between the IRI and the graph. peter
Received on Friday, 14 September 2012 14:33:36 UTC