Re: [TF-PP] Zero-length paths (ACTION-251)

On 08/06/2010 4:51 PM, Gregory Williams wrote:
> On Jun 8, 2010, at 11:45 AM, Birte Glimm wrote:
>> Thus, a (mathematically) natural interpretation would be to return
>> only subjects and objects because they are the elements of the
>> relations (as also Andy suggested below).  It still does what Greg
>> wants I believe. E.g. lets say G contains:
>> ex:a ex:mylabel "l1".
>> ex:mylabel rdfs:subPropertyOf rdfs:label
>> Greg's query is:
>> SELECT ?label WHERE {
>>        ?p rdfs:subPropertyOf* rdfs:label .
>>        ?s ?p ?label .
>> }
> My issue with this example was specifically so that it would handle not only the case you show (with a subproperty of rdfs:label), but also ones where there is no schema information at all. If the data only contained:
> <s>  rdfs:label "foo" .
> then I believe your approach wouldn't return any bindings for ?label, even though { ?label = "foo" } would be the intuitive result of the query, as far as I'm concerned.

An idea: We could define ?x :p{0} ?x as matching subjects+objects, and 
?x :p{0} :uri to match URI :uri regardless (and all the subjects+objects 
but that's not gong to change the matches).  Explicit mention adds to 
the set of possibilities.


Received on Tuesday, 8 June 2010 17:23:39 UTC