Re: [UCR] RIF needs different reasoning methods

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

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.
> 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).
>
>> 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.

Regards,

Francois