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Re: NAF v. SNAF - where is this being addressed?

From: Jim Hendler <hendler@cs.umd.edu>
Date: Wed, 29 Jun 2005 14:18:11 -0400
Message-Id: <p0620071dbee89453a6a4@[]>
To: edbark@nist.gov
Cc: public-rule-workshop-discuss@w3.org
Ed - see my reply to Mike Kifer re: what I was asking about SNAF - I 
make the main point - these are useful starting places, but don't 
constrain what an eventual charter needs to say.
  More specifically, I think some of your points below related to what 
I called in a different thread the difference between a "Web Rules 
Langauge" and a "Semantic Web Rules Language" -- I've argued these 
aren't identical.  If what we want is a syntax for the exchange of 
rule sets (i.e. I can write a set, you can read them and use them as 
they are) then IMO we should build an XML schema for rules and have a 
very simple semantics underlying it (so as not to overconstrain 
solutions).  On the other hand, if the goal is a distributed set of 
rules with the ability to link to other sets, reuse parts of other 
business processes, cut and paste one set of rules and edit for 
another application, etc. (which, as reflected in the OWL FAQ [1] was 
the hard part of going from traditional KR to OWL) then the task is 
harder, and NAF/SNAF in particular becomes trickier to apply and we 
need to be careful about how we delineate the goals.
  btw, I think the jury is still out as to whether a Web Rules 
Language or a Semantic Web Rules Language is preferable and to be 
chartered - but if it is the latter, we have to resolve what we're 
trying to do more carefully.

[1] http://www.w3.org/2003/08/owlfaq.html

At 12:35 -0400 6/29/05, Ed Barkmeyer wrote:
>Jim Hendler wrote:
>>   Seems to me if I see your rule set includes a NAF-based rule, and 
>>you give me a conclusion to something, that if I don't know what 
>>graph/KB/DB that was applied to, then I have no way to know whether 
>>I can use your result in my application
>Absolutely.  But in general, I can't take a rule set, with or 
>without NAF, and use it in my application without some knowledge of 
>the assumptions underlying it.  As Pat Hayes says, your universe may 
>be different from my universe, and so the same argument applies to 
>universal quantifiers.
>The point of SNAF is that if I know what reference KB we are 
>assuming for the ruleset, I can agree that the use of NAF makes 
>sense.  And there is a corresponding "SUQ" concept for the 
>interpretation of "for all x".
>>    Seems to me also that this has a big effect on the charter, as I 
>>don't know if there is an agreed upon use of SNAF for the Web, and 
>>would need to be something the WG would be required to elucidate.
>Well, I agree that the scope of any rule using NAF needs to be identified.
>But it is clear that there are "KBs" that are taken, across the 
>entire Web, to be the reference repositories for certain "fact 
>types", and the use of NAF on such a repository can be treated as 
>universally appropriate.  For example, no one should doubt the 
>validity of NAF reasoning over the IANA list of Internet addresses, 
>or the W3C list of W3C Recommendations.
>>  p.s. Note that in datalog, there is always the assumption that the 
>>rules and a particular database can be linked - on the Web, that is 
>>not necessarily true.
>I would argue that this is not quite the right consideration.  A 
>common set of "business rules", for example, may be applied over 
>different data/knowledge bases in different business units of the 
>organization responsible for the rules.  Similarly, a common set of 
>accounting rules may be legally required for all businesses in a 
>particular governmental classification, even though every such 
>business has its own database. And those rules may include NAF 
>rules, e.g. "if no payment has been recorded after 30 days, the 
>account is 'delinquent'".
>Datalog rulesets are clearly associated to a particular database for 
>"execution".  They are usually tightly coupled to a particular DB 
>schema, which greatly reduces the possibility of wider 
>applicability. But Web rulesets will also be coupled to a particular 
>database for "execution", just as Web ontologies will be coupled to 
>a particular knowledge base for "reasoning about individuals".  The 
>difference is that Web rulesets are based on some reference 
>ontology, and both the ontology and the ruleset must be 
>"interpreted" into the vernacular of the target knowledge base in 
>order to be "executed".  So the question is whether the ontology and 
>ruleset are *appropriate* to the specific knowledge base over which 
>you want to reason.  Whether that is the same knowledge base I am 
>using, or my trading partner is using, may or nay not be important. 
>But if it is important that they be the same, i.e. that there is a 
>reference knowledge base, either for all such reasoning, or just for 
>our joint business/research, that is a separate issue.
>Edward J. Barkmeyer                        Email: edbark@nist.gov
>National Institute of Standards & Technology
>Manufacturing Systems Integration Division
>100 Bureau Drive, Stop 8264                Tel: +1 301-975-3528
>Gaithersburg, MD 20899-8264                FAX: +1 301-975-4694
>"The opinions expressed above do not reflect consensus of NIST,
>  and have not been reviewed by any Government authority."

Professor James Hendler			  Director
Joint Institute for Knowledge Discovery	 	  301-405-2696
UMIACS, Univ of Maryland			  301-314-9734 (Fax)
College Park, MD 20742			  http://www.cs.umd.edu/users/hendler
Received on Wednesday, 29 June 2005 18:18:50 UTC

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