- From: Enrico Franconi <franconi@inf.unibz.it>
- Date: Wed, 2 Nov 2005 14:41:01 +0100
- To: Pat Hayes <phayes@ihmc.us>
- Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Hi Pat,
Here it is the example of why the definition of query answer using
union rather RDF-merge does not work as desired to capture what I
called (l3):
> l3) the bnodes names in a query have to be treated as told-bnodes,
> i.e., they have to match only with bnodes with the same name in the
> dataset.
GRAPH: :s :p _:b .
query 1: { ?x :p _:a }
query 2: { ?x :p _:b }
According to (l3) query 1 has the empty answer,
while query 2 has the answer [?x/:s].
using the semantics proposed by you:
G |= (G U Q)[s]
both queries have the answer [?x/:s]
In this case the user may wrongly gather that the triple <:s :p _:a>
was *explicitely* asserted in the graph.
cheers
--e.
Received on Wednesday, 2 November 2005 13:41:19 UTC