inference rule on rdfs:subClassOf

[ingeval]

Hi,

I am trying to understand the RDFS inference rules, in particular the rdfs:subClassOf inference. I was hoping a query such as

Code: Select all

sparql select * where {<class1> rdfs:subClassOf ?superClass};


will return all super classes of <class1>, including both directly asserted and inferred, however, it seems to me only asserted super classes are returned.
Anyone can help me clarify?

Here is what I did:

1. I have this data set, <a> is a subclass of <b>, and <b> is subclass of <c>.

Code: Select all

@base <http://example.com/test/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

<a> rdfs:subClassOf <b> .
<b> rdfs:subClassOf <c> .

<ia> rdf:type <a> .


2. add rule set

Code: Select all

rdfs_rule_set ('testrules', 'http://example.com/test/');


3. execute this query

Code: Select all

sparql
define input:inference "testrules"
select * where {<http://example.com/test/a> rdfs:subClassOf ?sup};


4. only <b> is returned, but I think <c> is also an answer as the result of rdfs:subClassOf inference.

[hwilliams]

Hi Yonggang,

As indicated in my email to you, I have been able to recreate the issue and reported to development for resolution ...

Best Regards
Hugh Williams
OpenLink Software

[ingeval]

thanks!

I just discovered a workaround for this issue:

if I add

Code: Select all

rdfs:subClassOf rdf:type owl:TransitiveProperty .


to the data set, i.e. inform Virtuoso to treat rdfs:subClassOf as transitive property, then everything worked as expected.

[hwilliams]

Hi

Ok, good to hear this is working for you as that is what development suggested also ...

Best Regards
Hugh Williams
OpenLink Software

[caha42]

Since this is an quite old thread and there have been some new versions out of Virtuoso, is this problem still actual? Because I am running into the same problem and the documentation still says that rdfs:subClassOf should be working out of the box (see http://docs.openlinksw.com/virtuoso/rdfsparqlrule.html).

I add the following triples:

Code: Select all

<http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?field=uid&term=C23.888.646.100.200> <http://purl.org/dc/terms/identifier> "C23.888.646.100.200"@en .
<http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?field=uid&term=C23.888.821.030.249> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.scai.fraunhofe
r.de/mesh> .
<http://www.scai.fraunhofer.de/mesh> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://www.w3.org/2004/02/skos/core#Concept> .


And then query:

Code: Select all

SELECT * WHERE {
<http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?field=uid&term=C23.888.646.100.200> rdf:type ?type .
}

And get the result:

Code: Select all

type
http://www.scai.fraunhofer.de/mesh

But expected to get:

Code: Select all

type
http://www.scai.fraunhofer.de/mesh
http://www.w3.org/2004/02/skos/core#Concept


Do I have an error somewhere or is the old bug still not fixed?

I am using Virtuoso OpenSource Version 6.1.4.

[hwilliams]

Hi

I have checked the rdfs:subClassOf example in the documentation and it work for me against a 6.1.4 build, this what is the ontology data and rule you are loading/creating here that is proving problematic ?

Best Regards
Hugh Williams
OpenLink Software

[caha42]

Hi,

I realized I just got the documentation wrong. I thought that rdfs:subClassOf would be recognized automatically in all the triples and not only in defined rule sets. So there was my problem. After I did it like in the example you posted the link to, everything worked fine.

But I really dislike that I have to create a rule set first, since my subClassOf relations are spreaded over ~300 files. Instead of making them all to rule sets, I grepped all subClassOf relations and collected them in one file, but anyhow, this is kind of additional work. I would prefer to be able to turn the subClassOf feature on in general, like it is possible in Owlim for example.

Best regards and thanks for your help,
Carina