Re: [UCR] RIF needs different reasoning methods

On Mar 13, 2006, at 4:33 AM, Gerd Wagner wrote:

>> My understanding is that derivation rules and integrity
>> constraints are
>> just a bifurcation of Horn rules (or sometimes the two halves of
>> something beyond Horn).  As such they fit easily into the same
>> semantics.
>
> Not really, there are both syntactic and semantic
> differences:
>
> - derivation rules, in general, correspond to Gentzen
>   sequents;
[snip]
> - integrity constraints, in general, correspond to
>   sentences of some logic (which may be classical FOL,
>   temporal FOL or some modal FOL); as emphasized by
>   SBVR,
[snip]
> Given all these differences, how can you say "they
> fit easily into the same semantics"?

While I wouldn't have said it the way Sandro did, there are attempts to 
formalize integrity constraints (with all their semantics and 
pragmatics) using the K and A operators (i.e., in MKNF):
	http://citeseer.ist.psu.edu/237686.html
	http://www.cs.utexas.edu/users/vl/mypapers/mbnf.ps

(Of course, using K & A is a little like using continuations to model 
threads and exceptions....you can do it, and it's cool, but, uh, it's 
generally harder than direct approaches.)

> The fact that, in certain circumstances, they may both
> take the form of a Horn formula does not mean they
> have the same semantics
[snip]

That I *heartily* agree with.

Cheers,
Bijan.