Re: [RIFWG] [Requirements?] A vision for the RIF

François Bry wrote:

> There is a clean and simple way out: RIF been made of 3 complementary
> yet distinct languages: a language of deduction rules, a language of
> normative rules, and a language of reactive rules.

We...ell. I'm not sure that is either clean or simple.

First, I still don't understand the semantic model for "reactive rules", but 
that's a minor point.

Second, Michael Kifer has argued that we can't get a useful semantics for a 
language that supports "normative" and "deductive" rules in combination.  So, 
bowing to his expertise, I can agree these must be separate languages.
But... Many applications for "normative rules" also want some kind of 
"deductive" (or perhaps "reactive"?) capability whose application in some 
sense "precedes" the application of a "normative ruleset".  So, if these are 
"separate languages", they have to be part of a "family", as Gerd says, and 
that family has to occasionally get together at dinner.

Third, (IMO) "at dinner" that family has to include the adopted children of 
FOL ethnicity: RDF and OWL.

Fourth, I'm not sure how quickly we will get agreement on the semantic model 
for a single "language of deduction rules".  We all know that there are 
multiple well-known semantic models for "rules-based inferencing".  Will we 
agree to use one semantics, with its limitations, as the standard? or agree to 
several semantics models, each of which corresponds to an "intended semantics" 
attribute of a ruleset?  And in the latter case, isn't the "normative" 
semantics just yet-another-semantic-model?

Finally, if all we can agree on is syntax that can support several possible 
semantic models (some of which will yield identical results for some 
rulesets), we will violate our Web responsibilities: We can't know all of the 
users/recipients of the ruleset. So we can't privately agree on the intended 
semantics for the exchange.  A web-published ruleset with an unspecified 
semantics is meaningless.

So I think what François suggests is only "simple" in theory:  We have to 
agree on more than one semantic model, document all the ones we agree on, and 
give them names, which are possible values for some attribute of the ruleset.

[And OBTW, if W3C had done that with OWL, we would have DL+ 22 combinations of 
letters for add-on features, guaranteeing that nearly no ontology would 
transfer successfully between engines -- exactly the opposite of the result 
that Bijan observed.]

-Ed

-- 
Edward J. Barkmeyer                        Email: edbark@nist.gov
National Institute of Standards & Technology
Manufacturing Systems Integration Division
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Received on Thursday, 20 April 2006 16:08:57 UTC