- From: Pat Hayes <phayes@ihmc.us>
- Date: Tue, 28 Feb 2012 09:36:41 -0600
- To: Ivan Herman <ivan@w3.org>
- Cc: Andy Seaborne <andy.seaborne@epimorphics.com>, RDF-WG <public-rdf-wg@w3.org>
On Feb 28, 2012, at 3:45 AM, Ivan Herman wrote: > Pat, > > I need explanation, 'cause I am lost, I am not ashamed to say that... > > > On Feb 27, 2012, at 22:42 , Pat Hayes wrote: > [snip] >> >>> >>> The use of a URI for a graph label in two different trig documents should mean the same thing but combining two datasets, like combining two graphs, will involve an application deciding that is can be done. >> >> But how will it? ANY two graphs are semantically consistent, on this account, > > If my understanding of [2] is correct, each graph must be, individually, consistent according to the RDF Semantics, ie, has to have a proper model. The models may be different for two different graphs with different labels, but I do not understand what you say... I should have said, any two graphs are consistent *with one another*. Put another way, there cannot be an inconsistency between something said on one graph and something said in a different graph. For example, suppose one graph says that :Joe :age '10'^^xsd:number and another graph says that :Joe :age '33'^xsd:number and a third graph says (in OWL) that :age is a functional property. Something wrong here, right? But no, not according to the proposed semantics. Put these three graphs into a single trig document, and this document has an interpretation, so it is consistent. So there is no inconsistency to be resolved: everything is fine, according to this semantics. >> and two graphs (with different labels) NEVER entail any graph larger than either of them (such as their merge, for example), according to the semantics in [2]. > > Again, I do not understand why. If two graphs have the same label, then their merge, with the same label, is entailed, again by [2]. With the same label, yes. I said, two graphs with different labels. If I put two copies of a graph into a single trig document with two different lables, one of the copies does not entail the other, even though they are the same graph. Pat > > Ivan > > > >> So all semantic relationships are reduced to triviality, so there can be no criteria available to check for acceptability on any semantic grounds. Remember, *every* URI might mean sometjhing completely different in another graph, so you can't say things like one graph says that x:joe is age 10 and the other says he is age 12: that URI might refer to Joe in one graph and Susan in the other, and the URI for the age property might mean age in one graph and being-a-handle-of in the other. Graphs become black holes of meaning, without any way for anything inside to influence or connect with anything outside. >> >>> >>> Islands aren't named or formally recognized - and one apps view of "usable together" may not be the same as another apps. >> >> Oh what a tangled Web we weave.... (Sorry, couldnt resist :-) >> >> Pat >> >>> >>> Andy >>> >>> [1] http://www.bbc.co.uk/doctorwho/dw >>> [2] http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/RDF-Datasets-Proposal >>> >>> >> >> ------------------------------------------------------------ >> IHMC (850)434 8903 or (650)494 3973 >> 40 South Alcaniz St. (850)202 4416 office >> Pensacola (850)202 4440 fax >> FL 32502 (850)291 0667 mobile >> phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes >> >> >> >> >> >> > > > ---- > Ivan Herman, W3C Semantic Web Activity Lead > Home: http://www.w3.org/People/Ivan/ > mobile: +31-641044153 > FOAF: http://www.ivan-herman.net/foaf.rdf > > > > > ------------------------------------------------------------ IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Tuesday, 28 February 2012 15:37:17 UTC