- From: Andy Seaborne <andy.seaborne@talis.com>
- Date: Mon, 04 Jan 2010 16:53:07 +0000
- To: Ivan Herman <ivan@w3.org>
- CC: Souripriya Das <SOURIPRIYA.DAS@oracle.com>, Lee Feigenbaum <lee@thefigtrees.net>, Axel Polleres <axel.polleres@deri.org>, W3C SPARQL Working Group <public-rdf-dawg@w3.org>
On 04/01/2010 12:31 PM, Ivan Herman wrote: > Hi Andy, >>> - I am not sure what "A path of length zero connects a graph node to >>> itself." means in terms of a triple pattern... >> >> ?x :p* ?y needs a meaning. :p* can appear in more complex paths >> (rdf:first*/rdf:rest). >> >> Working backwards from e.g. ?list rdf:first*/rdf:rest ?elt, ?list >> rdf:first* ?x would match with ?x equal to whatever ?list is. >> > > Hm. Alternatively, ?x :p* ?y would not match anything with length zero? Then ?list rdf:rest* ?elt does not match the beginning cell of a list and ?list rdf:rest*/rdf:first ?elt (which eventually I will write correctly!) does not find the first element of a list without making :p* different from the :p* in :p*/:q It does have a nice effect that :C rdfs:subClassOf ?class includes :C (as per inference rule that :C rdfs:subClassOf :C). An app can write "+" to skip the zero match "+" is '1 or more' where "*" is 'zero or more' Andy
Received on Monday, 4 January 2010 16:53:40 UTC