- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Thu, 20 Sep 2012 10:54:41 -0400
- To: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- CC: Pat Hayes <phayes@ihmc.us>, RDF WG <public-rdf-wg@w3.org>
On 09/20/2012 05:49 AM, Antoine Zimmermann wrote: > Le 19/09/2012 22:12, Peter F. Patel-Schneider a écrit : > [...] > >> I also have problems with any dataset semantics that isn't based on the >> actual form of the named graphs. > > I don't understand this. > >> Isn't a major use of datasets >> supposed to be for associating a graph with its source? > > Sure. This type of use case is compatible with the semantics. > > >> if so, neither >> of these two semantics seems to be correct, as the meaning of a named >> graph in a dataset is not a graph but is instead something like an >> equivalence class of graphs. > > I don't understand. Where do you see equivalence classes? Interpretations for named graphs talk directly about entailment. If you change an interpretation by replacing a named graph with an equivalent one, then the truth values don't change. > > >> The semantics then destroys the >> relationship between the name and the actual graph. > > It does not destroy anything because a semantics does not *do* anything. The > actual relationship between the name and the actual graph is written in the > dataset. > You could argue along these lines saying that the RDF semantics destroys the > relationship between the property names and the actual pairs > (subject,object) that are actually in the graph. > If you want to know what subjects or objects occur with a predicate inside a > graph, just look at the graph. There are APIs for this. > Same for datasets. In the semantics there is no notion of a relationship between a name and an actual graph. If named graphs and RDF datasets are supposed to carry a relationship between a name and an actual graph, then shouldn't the semantics reflect this? This is totally different from properties. No one should be arguing that RDF graphs are supposed to carry a relationship between a name and a set of pairs. Instead this is what the semantics does. > (Of course, you >> could always just ignore the semantics and directly use the graph from >> the dataset, but then what is the point of having the named graph there?) > > The data structure is also very important, just as in RDF graphs, the data > structure is already a nice way of organising the data, linking data > together, etc. Semantics does not have to come into play where it has no role. > > > --AZ Huh? If the meaning of a named graph is tied up with relating names to graphs, then the semantics certainly has a role there. peter
Received on Thursday, 20 September 2012 14:55:18 UTC