[Virtuoso-users] Bug with rdfs_rule_set and isIRI or isBlank

[Wenzel, Ken]

Hello,

we've recently encountered a potential bug
related to Virtuoso's inference rule support in combination
with isIRI and isBlank builtins in SPARQL queries:

The functions isIRI/isBLANK always return true/false for inferred
bindings whether the bound value is a BNode or not.

This behaviour was observed with the Windows (Windows XP) and 
the Linux version (Ubuntu 10.04) of Virtuoso 6.1.4.

Steps to reproduce the problem:

1. Insert some test data:
-------------------------

PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX test: <http://example/inferencetest#>

insert into <http://example/inferencetest#> {
        test:Tree a owl:Class ;
        rdfs:subClassOf [
                a owl:Restriction ;
                owl:onProperty test:hasChildren ;
                owl:allValuesFrom test:Node
        ] .
        test:Node a owl:Class .
        test:TheTree a test:Tree
}

2. Create rule set:
-------------------

rdfs_rule_set('http://example/inferencetest#',
'http://example/inferencetest#')

3. Execute SPARQL query with inference rules:
---------------------------------------------

define input:inference 'http://example/inferencetest#'

select * 
from <http://example/inferencetest#>
where {
    ?s a ?o filter (isIRI(?s) && isIRI(?o))
}

4. Observations:
----------------

The restriction BNode is filtered in the case when it occurs
as asserted ?s but not in the case when it is an inferred ?o.


Best regards,

Ken