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Re: Question about ontology query languages... (please reply!!!)

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Wed, 11 Apr 2007 17:56:05 +0100
Message-Id: <AAD27648-8535-461E-835B-C4FC18A8C8EF@cs.man.ac.uk>
Cc: semantic-web@w3.org
To: "Cristina Lancioni, Doctor in Computer Science" <cristina.lancioni@unicam.it>

On 10 Apr 2007, at 14:10, Cristina Lancioni, Doctor in Computer  
Science wrote:

> Hello,
> I'm a phd student in Information Technology at the University of  
> Camerino (Italy).
> I would like to know if it's possible to do recursive queries in  
> SPARQL.

"Recursive query" can mean several things.

> In fact I've this problem. I've an ontology in OWL with only  
> relations is-a.

Do you mean the subclass tree? are you using subclassof?

> This ontology is made like a tree. I would like to select a  
> subgraph made of the path from the leaf node to the root node  
> (result example: A(leaf) is-a B is-a C is-a D(root)).

Are you querying for class names?

> How could I do this using only a single query? Shoud I do this with  
> SPARQL? If not, do You know another ontology query language to do  
> this?

If you are building the ontology yourself, you could use a transitive  
role in the ontology (e.g., for is-a), then a standard sparql query  
will do the job (assuming that the store supports it).

There are some query languages that support a transitive closure  
operator in the query, e.g., the one with Kowari/whatever it's called  
now, the one in wilbur (which has more general regular expressions),  
or you might try SPARQL Rules
	<http://platon.escet.urjc.es/~axel/publications/GIA-TR-2006-11-28.pdf>

Vanilla sparql will not do the job.

You could also lobby your favorite engine implementor for an extension.

Cheers,
Bijan.
Received on Wednesday, 11 April 2007 16:55:27 GMT

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