- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Tue, 19 Feb 2002 08:58:21 +0200
- To: Pat Hayes <phayes@ai.uwf.edu>, Brian McBride <bwm@hplb.hpl.hp.com>
- CC: RDF Core <w3c-rdfcore-wg@w3.org>
On 2002-02-19 4:22, "ext Pat Hayes" <phayes@ai.uwf.edu> wrote: >> During the datatyping followup after Friday's telecon, I made >> the statement that if literals were subjects which took datatyping >> properties, they must be untidy -- and I was told this was incorrect. > > Then we were at cross purposes. > > There are two issues here: whether literals can be subjects, and > whether a literal node can have a datatype-sensitive meaning. I never said that literal subjects could not be tidy. I said literal subjects that were tidy could not bear meaningful datatyping qualification. I fully understood both issues, and was simply trying to make a point about the second case, where literal subjects would bear datatyping qualification. I think it *was* unclear for some of the other participants that I was talking about the second issue, though I tried to stress that, which is why I posted my examples and explanation. I consider the first case, in the context of tidy literals, to be so trivial as to not be worth bothering any time discussing. I can't imagine anyone caring to go to any trouble to get such uninteresting, anemic, useless tidy literal subjects. Who cares if tidy literals are subjects? *BUT*, since all of the debate previously about allowing literals as subjects would have presumed *untidy* and interesting literal subjects, I simply wanted it to be clear that the tidy/untidy distinction was "can't have your cake and eat it too" with regards to literals as subjects, that's all. > But this arises even if we > do not allow literals as subjects, as in the old P idiom (updated > here to use drange): > > aaa age "10" . > age rdfs:drange decimalInt . No. In the above example, tidy vs. untidy is irrelevant. The literal node does not itself denote the value or the lexical form. It is just a literal. For inline idioms, the data value has no explicit denotation in the graph. It is implied. Only the bNode idioms provide explicit denotation of values in the graph, and that is the primary (possibly only) difference between the inline idiom and the value triple idiom, when applying a union interpretation to rdfs:drange. Eh? > So, to repeat, the two issues are separate; and when separated, it is > the latter, not the former, that requires untidy literals. I thought > that we had decided the latter issue some time ago in favor of > tidiness. We did. And I had no problem with the first issue, but was concerned about folks who may read too much into the 'literal as subject' and think they might get interesting, useful literal subjects in the future. They won't. Tidy literals kills that possibility. > I suggest that we stick with the decision to have literals always > denoting themselves, under all circumstances, as a rock-solid > principle. I never suggested that would change. The union treatment of rdfs:drange does not change that. Only the bNode idioms provide explicit denotation of values in the graph. Literals are just literals. Period. > Literals are *never* contextual in their meaning; all the > datatyping cleverness applies to the bnode at the other end of the > triple. Well, literals themselves, in isolation bear no meaning, but as a component of a TDL pairing, they denote a lexical form, but it is not the literal *in the graph* that denotes the lexical form but the literal in the context of a TDL pairing that is treated as a lexical form. It's a fine distinction, but I think a clear one. > Then we can allow literals to be subjects with equinamity, > and still retain tidy literal nodes in the syntax. Your example then > has a datatyping clash in the merged graph, in just the same way as > if you had used bnodes rather than literals. No. You're missing the very critical point that rdfs:drange is taken as constraining the property value to the *union* of the lexical space and value space of the datatype. Thus, there is no type clash. > However, the first graph > is nonsensical on its face, since the triple > > "30" rdf:dtype decimalInt . > > says that the string '30' is in the *value* space of decimalInt, > which is presumably false, and would be immediately rejected by a > datatype checker. True, but... You're mixing datatyping solutions, Pat. If we had untidy, literal subjects, we would do things very differently than we are doing them now. You can't impose consistency of the present solution, which never considered untidy literal subjects, to the above examples. That's not fair. But it's also not relevant, so let's just drop it. I think we are (and have been) in agreement. Patrick -- Patrick Stickler Phone: +358 50 483 9453 Senior Research Scientist Fax: +358 7180 35409 Nokia Research Center Email: patrick.stickler@nokia.com
Received on Tuesday, 19 February 2002 01:56:51 UTC