- From: Alexandre Passant <alexandre.passant@deri.org>
- Date: Fri, 13 Mar 2009 18:47:08 +0000
- To: Lee Feigenbaum <lee@thefigtrees.net>
- Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
Le 13 mars 09 à 18:25, Lee Feigenbaum a écrit : > Alexandre Passant wrote: >> Hi, >> Le 12 mars 09 à 06:49, Lee Feigenbaum a écrit : >>> Next week I'd like to continue where we left off, with brief >>> discussions of some of the more "major" suggested features that >>> impact the query language itself. These include: >>> >>> Assignment >>> Property paths - Andy >>> Aggregates >>> Negation >>> Update >>> Basic Federated Query >>> Parameterized inference/control of inference >> I thinks that Path Length [1] may also be included in that list, as >> a major feature. >> As it strongly relates to property path: Andy, OpenLink, any >> objection to merge the two features in a single page ? >> (As path length does not makes any sense without the path itself, >> it's obvious for the inclusion in that direction, but I want to be >> sure both of you agree on adding another feature (lenght) to your >> path initial proposal.) > > I don't see these as being the same at all. I didn't meant they are the same, I meant that they're related and might be suggested as a single 'Path' feature that includes both regexp to define paths and filter for path length. i.e. what is done in Corese [1] with the related PathLength example [2] SELECT ?y { <http://example.org/bob> $path ?y . } FILTER (match($path, foaf:knows)) // Regexp for the path FILTER (pathLength($path) >= 1 && pathLength($path) <= 2) // length Without any pathLength filtering, the query is simply a property path query as proposed in [3], but that way of using a variable (rather than including the regexp directly as in ":foo rdf:type/ rdfs:subClassOf* :bar") allows imho more extensibility, especially for that length feature. Cheers, Alex. [1] http://www-sop.inria.fr/edelweiss/software/corese/v2_4_1/manual/next.php [2] http://www.w3.org/2009/sparql/wiki/Feature:PathLength [3] http://www.w3.org/2009/sparql/wiki/Feature:PropertyPaths > My understanding is that property paths allow me to specify in a > regular expression-like way an explicit chain that connects two > nodes. For path length, you need to start having variables match > arbitrary-length paths between nodes, right? (Once you ahve a > variable matching a path, then it's natural to add a function to get > the length of that path.) And that seems like a whole other ball of > wax to me. > > Am I misunderstanding? > > Lee -- Alexandre Passant Digital Enterprise Research Institute National University of Ireland, Galway :me owl:sameAs <http://apassant.net/alex> .
Received on Friday, 13 March 2009 18:47:49 UTC