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Re: [UCR] RIF needs different reasoning methods

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Mon, 6 Mar 2006 07:36:28 -0500
Message-Id: <51203bc37e5ed54e8767bc250dd23e7a@isr.umd.edu>
Cc: public-rif-wg@w3.org
To: Francois Bry <bry@ifi.lmu.de>

On Mar 6, 2006, at 6:38 AM, Francois Bry wrote:

> Dear Bijan,
>> Sorry, I missed the meeting. Are you arguing that RIF documents need
>> to be able to *specify* the intended reasoning method for those
>> documents?
> Yes, I do.

Ok.

>> Is this distinct from declaring their intended semantics?
> Yes, it is.

It's declaring their expressive profile? I mean, is it (anything like) 
the OWL species? Or the KIF conformance profiles?
	<http://logic.stanford.edu/kif/dpans.html#12.3>

Or does the actual proof theory matter?

>>> The following is a (sketch of an) application scenario illustrating
>>> different forms of reasoning with rulesets that, in my opinion, the
>>> RIF should support.
>>
>> What is the nature of that support? I mean, pragmatically speaking,
>> what needs to be done to enable such support?
> To make it possible to distinguish between different fragment of RIF:

Ok. Was there debate about this? Against this?

> 1. declatratibe RIF rules, themselvbes distinguished into 1.1 deduction
> rules and 1.2 normative rules
> 2. reactive rules



>> [snip]
>>> A rule like the previous one is similar to a database view (also
>>> called deduction rule): it gives rise to (deterministically) derive
>>> new information from information explicitely stated. Simple and
>>> efficient reasoning techniques (referred to as 'constructive
>>> reasoning') are sufficient for this, especially no excluded middle or
>>> refutation are needed.
>>
>> Isn't resolution a refutation technique? Did you mean something 
>> stronger?
> REsolution (including SL resolution) are refuytartion methods. SLD
> resolution is not - in spite of a common belief.

Ok.

>> Aren't you just saying that there is a subset of the RIF for which
>> there are known efficient techniques?
> Yes, I do.
>> I guess I'm still confused by the impact of these points on the spec.
> In my opinion, there is a requirement that obne can explicitely state
> what RIF fragment is used (cf. above).

Sure.

>>> Note that existing OWL reasoners only address 2 above. They can
>>> perform 1 but at unnecessary costs.
>>
>> Er...not necessarily. KAON2? Actually, regular tableaux based
>> reasoners can do pretty well, depending. (Granted, they do not
>> typically use secondary storage, but they can do quite well.)
> I am not saying they do not "do well". I am sayinmg, they do other
> things than those mentioned in the scenario.

Well, if they give the same answers....isn't everything else just an 
implementation detail? I mean, so what if the engine can do more or 
does it another way?

This doesn't mean it's not worth identifying important fragments and 
profiles (though that can be quite the painful game...hard to get 
right).

Cheers,
Bijan.
Received on Monday, 6 March 2006 12:36:38 GMT

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