Re: To embed or combine

> The most important argument is that the embedding stands on its own feet,
> while the combined semantics is of limited use, since we need the embedding
> anyway.

We don't necessarily /need/ the embedding if we define a model-theoretic
combination [*], it is just nice to have as an appendix, to show how
reasoning can be done with the combination.  Just like, as you suggested
in an earlier e-mail, we could use the model-theoretic combination in an
appendix as a justification for choosing a particular embedding in case
we go for the embedding.

> Regarding (2) my argument was not what you wrote, but that Jos' document
> essentially specifies a full-blown combined language. The embedding alone
> is sufficient in my view. It allows people to use rules and RDF together,
> but it does not define a normative combined language.  By defining an
> embedding, we already achieve all the goals with respect to RDF, which were
> listed in the charter.

Whether we define the semantics of the combination based on a model
theory or based on an embedding in RIF, in both cases we define a
combined language, which is normative.

Best, Jos

> 
> 
> 	--michael  
> 
>> <chair>
>> The status of the discussion regarding Jos' RDF compatibility section appears to 
>> be mired in whether the normative semantics of RDF in RIF should be specified in 
>> the model theory through a "combination" of RIF and RDF semantics, or through an 
>> "embedding" of RDF semantics in RIF (as rules).  The two approaches have been 
>> shown by Jos to be equivalent.
>>
>> At the moment I have not seen any technical arguments supporting one approach or 
>> the other.  Michael prefers the "embedding" on the basis that:
>>
>> (1) the "combination" is more complicated than the "embedding" and thus more 
>> difficult to understand.
>>
>> (2) it is not our job viz. our charter to specify a model theoretic approach to 
>> the RDF/RIF combination
>>
>> Jos seems to prefer the "combination" and argues re: (1) that:
>>
>> (3) it is no more difficult to understand the "combination" than the RIF model 
>> theory.
>>
>> As chair, my own read of the charter does not provide any particular help on 
>> (2), I'm not quite sure what Michael is referring to there.  It is certainly our 
>> job to specify how RIF and RDF should be used together, and as chair I interpret 
>> this as meaning we should have a normative standard for that.
>>
>> Thus, as suggested by Michael, it seems to me we are at a difference in 
>> preference only, and I see no alternative other than to call a vote.  It seems 
>> to me the vote is about which approaches to make *normative*:
>>
>> 1) The model-theoretic "combination" of RIF and RDF is normative
>> 2) The "embedding" of RDF semantics as RIF rules is normative
>> 3) Both the "combination" and "embedding" are normative (What would that mean?)
>> </chair>
>>
>> -Chris
>>
>>
>> -- 
>> Dr. Christopher A. Welty                    IBM Watson Research Center
>> +1.914.784.7055                             19 Skyline Dr.
>> cawelty@gmail.com                           Hawthorne, NY 10532
>> http://www.research.ibm.com/people/w/welty
>>
>>
>>
> 
> 
> 

-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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