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RE: Reminder: pending discussion "membership" (pending discussion on ACTION-350)

From: Paul Vincent <pvincent@tibco.com>
Date: Fri, 7 Dec 2007 01:12:59 -0800
Message-ID: <8F4A4531BB49A74387A7C99C7D0B0E0503655242@NA-PA-VBE02.na.tibco.com>
To: "Dave Reynolds" <der@hplb.hpl.hp.com>, "Michael Kifer" <kifer@cs.sunysb.edu>
Cc: "Public-Rif-Wg \(E-mail\)" <public-rif-wg@w3.org>

> Using your data modelling language of choice. In the case of the
> Semantic Web stack, of which RIF is a part, the answer is RDFS/OWL.

Semantics schemantics. RIF includes non sem web requirements/features
etc, so it at best is a "shared part" of the Sem Web stack. IMHO. :)

> I am convinced that including these primitives moves RIF from the
domain
> of rule interchange into that of data model interchange. Had that been
> explicitly part of the RIF charter I am not certain we would have
> approved the formation of RIF.

Funny I originally drafted a similar point in my other response, on the
premise that Michael used the term "knowledgebase" instead of rulebase,
and that a Knowledge Interchange Format should be considered an
extension to RIF, if a KIF is desired.

But, pragmatically, quite often rulebases (eg in PR) include things like
local variable definitions, and sometimes even local subclass
definitions, to simplify rule language expressions when the domain
schema is "fixed" and needs "extending" in the rule system. So I have
some sympathy for Michael's position. 

1. For the RIF use cases, we would typically want (for PR) an XML doc +
schema to form the factbase. 

2. The RIF charter implies (per my reading) that anything outside of the
definition of rule should be considered a non-core extension.

3. The AI / Sem Web community are divided on the value of class
membership constructs in BLD.

My simple inference from this discussion that perhaps BLD should be
BLCore (no "schema features") and BLDialect (BLCore + "schema
features")? 

Paul Vincent
TIBCO | ETG/Business Rules 
 

> -----Original Message-----
> From: public-rif-wg-request@w3.org
[mailto:public-rif-wg-request@w3.org]
> On Behalf Of Dave Reynolds
> Sent: 07 December 2007 08:52
> To: Michael Kifer
> Cc: axel@polleres.net; Public-Rif-Wg (E-mail)
> Subject: Re: Reminder: pending discussion "membership" (pending
discussion
> on ACTION-350)
> 
> 
> Michael Kifer wrote:
> > CSMA had an action to bug me about the ## feature :-)
> > I thought that others might also be interested, so I am including my
> > arguments below.
> >
> > First, one needs to be able to specify that one class is a subclass
of
> > another class **as part of the KB**.
> 
> I disagree, at least if by KB you mean RIF rules rather than RIF rules
+
> externally specified ontology or data model.
> 
> Expressing data models or ontological models and any subClass
relations
> associated with them is not a RIF requirement.
> 
> > For instance,
> >
> > student##person.
> > father(person)##person.
> >
> > In KB apps this is used for reasoning, not just as part of a data
> > model. How would one specify this info otherwise?
> 
> Using your data modelling language of choice. In the case of the
> Semantic Web stack, of which RIF is a part, the answer is RDFS/OWL.
> 
> In the case of XML Schema models then complex types can be related by
> both extension and restriction in ways that don't neatly map to
subClass.
> 
> > Here is a more sophisticated example: parametrised lists.
> >
> > list(?Subclass) ## list(?Super) :- ?Subclass ## ?Super.
> >
> > (List of FOOs is a subclass of lists of BARs if FOO is a subclass of
> > BAR. We could have list(father(person)), for example.)
> >
> > RDF's subclassOf does not cut it because
> >
> > 1. It imposes additional axioms, which are not commonly accepted.
> > 2. It is also not even defined for classes specified using function
> terms
> >    (like list(?Foo)).
> >
> > Both arguments are also applicable to the RDF membership
relationship.
> >
> > I am convinced that throwing out these primitives serves no purpose
and
> > will just gratuitously cripple the BLD.
> 
> I am convinced that including these primitives moves RIF from the
domain
> of rule interchange into that of data model interchange. Had that been
> explicitly part of the RIF charter I am not certain we would have
> approved the formation of RIF.
> 
> Dave
> --
> Hewlett-Packard Limited
> Registered Office: Cain Road, Bracknell, Berks RG12 1HN
> Registered No: 690597 England
Received on Friday, 7 December 2007 09:13:33 GMT

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