convenient way to generate (!) cross product of resultset of a subquery?

Dear all,

I have to write a query where I
1) want to select some entities with a subquery S, let's call the result set R
2) take the crossproduct R x R,   and
3) apply some filter on R x R
Below you find a working query like that, acting on some gene data.
The crucial point for me is: In order to obtain R x R, I use the subquery S twice.
This is something I don't like: Not-so-smart SPARQL processors would run the
subquery twice, though theoretically, it would be sufficient to run S only once,
if there was an easy way to "construct" from the result set R the cross-product R X R.
So my question is: Is there a better way to write that query without running S twice?
Is there a convenient way to let SPARQL generate R x R, when there is a SPARQL query
which generates R?

Best
Frithjof



select  ?gene1  (concat(">= ",xsd:string(?cdetected2)," detected") as ?o1)
where
{
    {
        #
        # subquery S, first instance
        #
        select (?gene as ?gene1)  (count(?ta1) as ?cdetected1)
        where
            {
            ?gene a :Gene .
            ?ta1 a :Textual_Annotation .
            ?ta1 :has_involved_gene ?gene .
            ?ta1 :has_strength :level_detected .
            }
        GROUP BY ?gene
        ORDER BY DESC(?cdetected1)
        LIMIT 5
        }

        {
        #
        # subquery S, second instance
        #
        select (?gene as ?gene2)  (count(?ta1) as ?cdetected2)
        where
            {
            ?gene a :Gene .
            ?ta1 a :Textual_Annotation .
            ?ta1 :has_involved_gene ?gene .
            ?ta1 :has_strength :level_detected .
            }
        GROUP BY ?gene
        ORDER BY DESC(?cdetected2)
        LIMIT 5
        }
        #
        # filter condition on R X R
        #
        FILTER (?cdetected1>=?cdetected2)
}


Dr. Frithjof Dau
Senior Researcher, Business Intelligence Practice   I   SAP Research Dresden
SAP AG   I   Chemnitzer Str. 48   I   01187 Dresden   I   Germany

T +49 351 4811-6152   I   F +49 6227 78-51425   I   mailto: frithjof.dau@sap.com<mailto:frithjof.dau@sap.com>
www.sap.com<http://www.sap.com>


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