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Re: First order logic and SPARQL

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Sun, 5 Sep 2010 23:17:32 +0100
Cc: Semantic Web <semantic-web@w3.org>, public-sparql-dev@w3.org
Message-Id: <DE58F9E8-C1D8-4C9C-8014-A2C3FB537088@cs.man.ac.uk>
To: Bob MacGregor <bob.macgregor@gmail.com>
On 5 Sep 2010, at 22:48, Bob MacGregor wrote:
[snip]
> I would  be interested to learn of a datalog-with-negation  
> implemented by translating to SPARQL,
> since datalog and its variants is IMO intuitive.

That seems like an unlikely direction, since datalog engines are  
generally at least somewhat older and perceived (correctly I think) as  
more fundamental. (I.e., if I were starting such an implementation,  
I'd start with Datalog, then reduce SPARQL to it.)

People do implement Datalog by reduction to SQL (without recursion, so  
not just non-recursive SQL) but that's to exploit existing SQL  
engines. Perhaps as SPARQL engines get ever more nice, people will do  
that with Datalog as well.

Perhaps people will do RIF to SPARQL.

> Are the results that show a mapping between
> a datalog variant and SPARQL just papers, or has someone actually  
> implemented a Datalog-like
> front end that translates to SPARQL?  I'd like to see that.  Note:  
> Axel cites a paper that translates
> in the other direction -- that's not what I'm after.

I don't know of any generic such toolkit, but e.g., the QuOnto system  
exposes both a SPARQL and a Datalog interface:
	http://www.dis.uniroma1.it/quonto/?q=node/26

I wouldn't be surprised if similar systems didn't also expose the  
direct datalog interface.

If you want to write Datalog and query arbitrary SPARQL systems, I  
shouldn't think it be that difficult to write a preprocessor for at  
least a reasonable fragment. I'd be surprised if it were a huge win  
for most users.  SPARQL's SQLyness seems accessible enough and the  
tutorials etc. are quite reasonable.

Cheers,
Bijan.
Received on Sunday, 5 September 2010 22:18:03 GMT

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