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Re: AW: Two issues with RIF-Core

From: Bijan Parsia <bparsia@cs.manchester.ac.uk>
Date: Sat, 9 May 2009 18:12:23 +0100
Cc: RIF WG <public-rif-wg@w3.org>
Message-Id: <99ECAAC6-0C96-40EB-8001-7D44591A3FA9@cs.manchester.ac.uk>
To: Sandro Hawke <sandro@w3.org>
On 9 May 2009, at 13:40, Sandro Hawke wrote:
[snip]
> Right.  The interesting/challening part, I believe, is that Gary wants
> to translate frames to Java objects.  Doing so will require some
> cleverness, since there are significant semantics/functionality
> differences, but hopefully will give significant performance gains.
> Ternary predicates are typically not super fast at matching (a,b,?).

Really?

> (For example, SWI-Prolog uses a specially indexed structure for RDF
> triples/quads, because normal predicate indexing is too slow.)

I wouldn't think that's the issue. Predicate indexing is typically one  
of the more optimized part of a Prolog engine (for obvious reasons). A  
uniform ternary predicate *defeats* predicate indexing because there's  
only one predicate. By default, IIRC and it hasn't changed, most  
Prolog engines do predicate plus first argument indexing, though you  
can change that, e.g.,:
	http://www.lix.polytechnique.fr/~catuscia/teaching/prolog/Manual/sec-3.11.html#sec 
:3.11.1
	http://www.lix.polytechnique.fr/~catuscia/teaching/prolog/Manual/sec-3.12.html#index/ 
1

Cheers,
Bijan.
Received on Saturday, 9 May 2009 17:13:04 GMT

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