tdbquery versus construct

[Benson Margulies]

I seem to be missing something about CONSTRUCT queries.

This select query works and returns some things...

PREFIX rex:   <http://www.basistech.com/ontologies/2010/6/rex.owl#>
PREFIX owl:   <http://www.w3.org/2002/07/owl#>
PREFIX x-arq: <urn:x-arq:>

select ?entity ?pred ?val

WHERE
{
        GRAPH x-arq:UnionGraph {
           ?entity rex:hasNormalizedText "Asia" .
        }
}

But this construct query just prints the prefixes:


PREFIX rex:   <http://www.basistech.com/ontologies/2010/6/rex.owl#>
PREFIX owl:   <http://www.w3.org/2002/07/owl#>
PREFIX x-arq: <urn:x-arq:>

CONSTRUCT {
# all tuples with the selected entity as a subject
?entity ?pred ?val .
# ?corefEntity ?pred ?val
}
WHERE
{
        GRAPH x-arq:UnionGraph {
           ?entity rex:hasNormalizedText "Asia" .
#          ?corefEntity owl:sameAs ?entity
        }
}