- From: Andy Seaborne <andy.seaborne@epimorphics.com>
- Date: Mon, 02 Apr 2012 21:46:21 +0100
- To: public-rdf-wg@w3.org
Take 2: (pressed "send", not "save" ... sigh ...) try again: On 02/04/12 16:36, Sandro Hawke wrote: > On Thu, 2012-03-29 at 09:25 -0700, Charles Greer wrote: >> I really like this solution and it seems to satisfy the use cases >> familiar to me from when I actually worked a lot with RDF in the wild. >> >> One thing I'm tripping over though -- The scope of a TRIG document or >> RDF dataset in effect 'closes the world.' Is the idea of "merge" only >> within a TRIG document/dataset? >> >> I can only see two ways to really assert a graph literal -- either by >> sanctifying the boundaries of a dataset, thereby making merges with >> external data problematic, or by signing bytes. Am I missing something, >> as usual? > > There's some misunderstanding here, yes. Maybe you can talk through > some particular thing you imagine doing, involving merging and TriG, and > I'll be able to pick it up. From what you've written, I'm confused. > > Maybe I can clarifying by translating this TriG document: > > <u1> {<a> <b> <c> } > > into this English declaration: > > The URI 'u1' denotes something, and that thing has exactly one > associated RDF Graph. That associated RDF graph consists of > one RDF triple, which we can write in turtle as "<a> <b> <c>". Clearer, but not what I would have expected. Why "exactly one associated RDF Graph"? RDF is all about partial descriptions of things. If <u> { <a> <b> <c> . <x> <y> <z> . } then I'd have expected <u> { <a> <b> <c> } and also <u> { <x> <y> <z> . } I guess the concrete examples will help - the choice of URI scheme for <u> and it's scope becomes very important - it's be clearer to me exactly what is being labelled and how. > So, perhaps it's more clear, now. If you merged that with another TriG > document: > > <u1> {<a> <b> <d> } > > Then, trying to accept both documents at onces, you'd be saying: > > The URI 'u1' denotes something, and that thing has exactly one > associated RDF graph. In one document that associated graph is > claimed to be the RDF triple "<a> <b> <c>", but in another > document that graph is claimed to be the RDF triple "<a> <b> > <d>". > > So, in this case, you can try to merge the documents, but when you do, > you find there is a contradiction, since there is only allowed to be one > associated graph, but in this case there are two different ones. Technical point: even if they are unique graphs, isn't the right conclusion: <c> owl:sameAs <d> . unless the "{ ... }" is and not a graph itself, but, say, a representation of a graph, or is it that, they are not equal as literals, considered as a set of triples with no interpretation. But if everything is quoted, nothing is ever equal. Workable, but a completely different architecture from the ground up - it's like having only reified statements. Andy
Received on Monday, 2 April 2012 20:46:52 UTC