- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Wed, 23 Feb 2005 10:35:06 -0500
- To: Pat Hayes <phayes@ihmc.us>
- Cc: andy.seaborne@hp.com, RDF Data Access Working Group <public-rdf-dawg@w3.org>
- Message-ID: <20050223153506.GA21895@w3.org>
On Mon, Feb 21, 2005 at 12:52:40PM -0600, Pat Hayes wrote: > >3. SPARQL QL publication > > > >ACTION: EricP, make sure editor's draft as an inline issue (to be > >published) that we need to work this out > >DONE: http://www.w3.org/TR/2005/WD-rdf-sparql-query-20050217/ > > I notice this in 11.2.1.2: > > used in conjunction with optional, it can be used to test whether a > graph pattern with at least one variable in it has been matched. When > also used in conjunction with not, it can test to see that a triple > has not been asserted. This is called Negation as Failure in logic > programming. > > but NOT does not appear in the grammar anywhere. Is this an editing > bug, or am I missing something? fixed. or at least changed... [[ One may test that a graph pattern is not expressed by specifying an optional graph patten that introduces a variable and testing to see that the variable is not bound. This is called Negation as Failure in logic programming. This query matches the people with a name but no expressed mbox: PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?name WHERE ( ?x foaf:name ?name ) OPTIONAL ( ?x foaf:mbox ?mbox ) AND !bound(?mbox) ]] If there were a rule that everyone had an mbox, one would need to: AND isBnode(?mbox) and if there *might* be such a rule: AND !bound(?mbox) || isBnode(?mbox) Should that go into the spec? All this will make Pat shudder, I'm quite sure. -- -eric office: +81.466.49.1170 W3C, Keio Research Institute at SFC, Shonan Fujisawa Campus, Keio University, 5322 Endo, Fujisawa, Kanagawa 252-8520 JAPAN +1.617.258.5741 NE43-344, MIT, Cambridge, MA 02144 USA cell: +81.90.6533.3882 (eric@w3.org) Feel free to forward this message to any list for any purpose other than email address distribution.
Received on Wednesday, 23 February 2005 15:35:06 UTC