- From: Kendall Clark <kendall@monkeyfist.com>
- Date: Tue, 22 Mar 2005 15:02:25 -0500
- To: "Seaborne, Andy" <andy.seaborne@hp.com>
- Cc: DAWG Mailing List <public-rdf-dawg@w3.org>
On Tue, Mar 22, 2005 at 06:06:25PM +0000, Seaborne, Andy wrote: > I had a quick scan (and will look more later). 2 (related) comments: Thanks for looking, Andy. > 1/ the handling of optional by an attribute. It seem more systematic to > define a tag c.f.: Hmm, perhaps. The element v. attribute thing is endless, of course, I just thought that saying a thing is optional is an attribute of that thing, rather than something that relates one or things together, which is what a UNION is. I think it's 12 of one, 15 of the other. -shrug- > 2/ Basic patterns and triple patterns > > Something like { ?s ?p ?o } can be viewed as a single triple pattern or it > can be a single triple pattern in a group. Yes, I struggled with understanding this bit of the SPARQL grammar. I'm not sure I favor one or the other ways of looking at it; in my view, the XML serialization should definitely be the tail and the end-user syntax should be the dog. > The view as group-triples makes more sense to me because of the extension > to { ?s ?p ?o . ?a ?b ?c . } - that is a group of two triple patterns (a > basic pattern). Right. > If pattern-groups are the only thing that can have triple patterns then > there is no need for a schema to have to cope with triple pattern or group > at each point. > > pattern-groups also hold constriants, optional, GRAPHs. > > I think this is close to the examples - a bit further away from the schema > with it's tpattern and gpattern. Sorry, I don't understand what you mean here. > It does introduce an extra level of XML but it makes it much easier to > process because of the regularity. In compensation, it loses an atrribute > and makes the schema simpler (less variability). Loses the optional attribute you mean? > The top of query is always a pattern-group (like the {} round a query > pattern in the human syntax). Yeah, this is definitely the part of the grammar I had the most trouble with (save for arbitrary expressions as constraints). I'll rethink it again with yr comments in mind. Kendall
Received on Tuesday, 22 March 2005 20:06:20 UTC