Re: [RT] rethinking the need for inferencing

From: Stefano Mazzocchi <stefanom_at_mit.edu>
Date: Tue, 07 Mar 2006 13:49:39 -0800

Arjohn Kampman wrote:
> Hi Stefano, others,

Hi Arjohn,

> Hope you don't mind me breaking into this discussion.

Not at all! It's actually why I wrote the RT in the first place :-)

> I have the
> impression that what you are aiming for is similar to what we intend(ed)
> to accomplish with Sesame's stackable Sail objects:
> http://openrdf.org/doc/sesame2/system/ch05.html

Yes, I'm aware of your work on stackable sail and I must say that it
sounds exactly like what we need.

> Stefano Mazzocchi wrote:
> [...]
>> All transformation phases require access to the input data stream for
>> the transformation to happen, some of these retain state and some do
>> not. It is always preferable to have stages that do not retain state
>> (or that retain, reliably, a small state in a windowed scenario)
>
> Such a one-way model is often too restrictive. In the context of
> Sesame's Sail API, such a model would only allow forward-chaining
> inferencers. Based on our experience with such inferencers in Sesame,
> this isn't going to scale to large amounts of data.

> The Sail API in Sesame 2 was revised to also allow query rewriting,
> allowing a Sail implementation to use a combination of forward- and
> backward-chaining. The paper "Time Space Trade-offs in Scaling up RDF
> Schema Reasoning" might be of interest to you:
> http://wwwis.win.tue.nl/~jbroekst/papers/time-space-WISE05.pdf

Very interesting. Is there anything more explicit about what type of
'query rewriting' operations are performed?

-- 
Stefano Mazzocchi
Research Scientist                 Digital Libraries Research Group
Massachusetts Institute of Technology            location: E25-131C
77 Massachusetts Ave                   telephone: +1 (617) 253-1096
Cambridge, MA  02139-4307              email: stefanom at mit . edu
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Received on Tue Mar 07 2006 - 21:48:02 EST

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