Re: Agenda - 12 Jun 2007 @ 14:30UTC

* Lee Feigenbaum <feigenbl@us.ibm.com> [2007-06-12 03:06-0400]
> ACTION: ericP to walk through one full example of representing an 
> algebraic expression using the XPath-based facet stuff

chimezie and i went over this at the end of the telecon. i just
noticed that i had said i'd do this for everyone. i think it's
slightly more useful for the audience if i don't couch it terms of the
folded algebraic expressions but instead a simple "does SPARQL do X?"
question.

Suppose you want to find the tests for { A OPT B OPT C }. Go to
http://www.w3.org/2005/01/yacker/uploads/SPARQL and dream up a query:

  SELECT *
   WHERE { ?s1 ?p1 ?o1 
           OPTIONAL { ?s1 ?p1 ?o1 }
           OPTIONAL { ?s1 ?p1 ?o1 } 
         }
stick it in the "Input some text to test" box and submit Submit SUBMIT!!!
  http://w3.org/brief/NDY=
A trimmed view of the parse tree (as XML) looks like:

<Query>
  <SelectQuery>
    <WhereClause>
      <GroupGraphPattern>
        <TriplesBlock>
        </TriplesBlock>
        <GraphPatternNotTriples>
          <OptionalGraphPattern>
            <GroupGraphPattern>
              <TriplesBlock>
              </TriplesBlock>
            </GroupGraphPattern>
          </OptionalGraphPattern>
        </GraphPatternNotTriples>
        <GraphPatternNotTriples>
          <OptionalGraphPattern>
            <GroupGraphPattern>
              <TriplesBlock>
              </TriplesBlock>
            </GroupGraphPattern>
          </OptionalGraphPattern>
        </GraphPatternNotTriples>
      </GroupGraphPattern>
    </WhereClause>
  </SelectQuery>
</Query>
  http://www.w3.org/2007/06/12-A-OPT-B-OPT-C.xml
The pattern

/Query/SelectQuery/WhereClause/GroupGraphPattern
  [TriplesBlock]
  [GraphPatternNotTriples[1]/OptionalGraphPattern]
  [GraphPatternNotTriples[2]/OptionalGraphPattern]

will detect that pattern.

An XSLT like 

  http://www.w3.org/2007/06/12-A-OPT-B-OPT-C.xsl


http://www.w3.org/2005/08/online_xslt/xslt?xslfile=++http%3A%2F%2Fwww.w3.org%2F2007%2F06%2F12-A-OPT-B-OPT-C.xsl&xmlfile=++http%3A%2F%2Fwww.w3.org%2F2007%2F06%2F12-A-OPT-B-OPT-C.xml&content-type=&submit=transform
  (or, briefly, http://w3.org/brief/NDc= )
shows the match.
-- 
-eric

office: +1.617.258.5741 NE43-344, MIT, Cambridge, MA 02144 USA
mobile: +1.617.599.3509

(eric@w3.org)
Feel free to forward this message to any list for any purpose other than
email address distribution.