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

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Fri, 07 Dec 2007 09:21:55 +0000
Message-ID: <475910B3.8030907@hplb.hpl.hp.com>
To: Paul Vincent <pvincent@tibco.com>
CC: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

Paul Vincent wrote:
>> 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. :)

You took my quote out of context. My point was there are different 
stacks RIF might want to work with each of which already has their own 
way of handling these things.

At previous F2F we've agreed that the two important stacks it needs to 
work with are semweb and XML.

The sentence you quoted was saying "*if* you are working in semweb then 
...". Likewise the next one was saying "*if* you are working in XML 
Schema then ...".

>> 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. 

Sounds like you have a use case to share! Christian has previously said 
this would be very unusual in PR applications.

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

Exactly. So how are subclass relations supposed to be connected to XML 
Schema?

Dave
-- 
Hewlett-Packard Limited
Registered Office: Cain Road, Bracknell, Berks RG12 1HN
Registered No: 690597 England


> 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 09:22:32 GMT

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