[Pellet-users] Pellet & SparQL: questions

[Silvia]

Hi,


i've some question about SparQL variables and Pellet. I've read that in
SparQL syntax all "?x" variables (be they in SELECT or in some BGP) are
distinguished.. that is they have to bind some instance in the ABOX.. is
it right?

I mean if i have a query like:

SELECT ?x

{ ?x :someproperty ?y}

?x and ?y are both distinguished variables, with the only difference
that the second is projected-away?


Another question i have is:  existentially quantified variables,
represented by bnodes (such as _:b0), work only on objectproperties or
also on properties that have xsd: as range? (such as Datatype properties)

The problem with Pellet is that if i ask for:


SELECT  ?x
WHERE

{
	?x rdf:type :Person .
	?x :hasName ?y .
}

where :hasName is a Datatype Property, everthing works fine.. if i ask for:


SELECT  ?x
WHERE


{
?x rdf:type :Person .
?x :hasName _:b0 .
}

Pellet returns:
DL Expressivity: ALCHF(D)
Consistent: Yes
Exception: java.lang.ClassCastException:
org.mindswap.pellet.datatypes.XSDSimpleType cannot be cast to
org.mindswap.pellet.datatypes.AtomicDatatype

i suppose that bnodes work only with properties linking classes with
classes (or restrictions).. but i don't understand why i have the same
error with the following query..

SELECT  ?x
WHERE
{
	?x rdf:type :Person .
	?x :hasName ?y .
	?x :hasRiskClass _:b0
}

i mean, the only Datatype property here is :hasName and in that triple
(?x :hasName ?y) there are no bnodes!


The last question is: what is the best way to test Pellet consistency
timings? I've seen that with Pellet is furnished a Java Class and i'm
using it..


thank you


Silvia D.