Jaroslav Pullmann wrote:
Hello,
to check for property cardinalities within an RDF document I used
following queries:
- for cardinality 0-1: NOT(Q2)
- for cardinality 1: Q1 AND NOT(Q2)
- for cardinality 1-n : Q1
# Q1
ASK
WHERE
{
?s rdf:type pfx:Foo; pfx:bar ?b .
}
# Q2 - no solutions, no duplicates
ASK
WHERE
{
?s rdf:type pfx:Foo;
pfx:bar ?b;
pfx:bar ?b1
FILTER(?b != ?b1)
}
Could these queries be formulated in a simpler, more elegant way ?
I agree with Axel that in standard SPARQL these are basically the way to
go. Just wanted to point out:
http://esw.w3.org/topic/SPARQL/Extensions/Aggregates
Several SPARQL implementations extend SPARQL with a COUNT() function
that would make this much easier. For example, using Glitter (Open
Anzo), I'd write:
SELECT (COUNT(?o) AS ?cardinality)
WHERE {
?s a pfx:Foo ; pfx:bar ?o .
}
Lee
