Re: To embed or combine

Michael Kifer wrote:
>> Michael Kifer wrote:
>>>>> 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.
>>> Publish the semantics without the embedding, and see what the reaction will be.
>>> I suspect that it will be: Huh? What do I do with this?
>> Yes, probably.  And publish the embedding without any justification and
>> the reaction will be:  Why this embedding?
>>
>>> The point is that the embedding is trivial and easy to explain. 
>> It is certainly not trivial.
>> Whether it is easier to explain is a matter of point of view, and also
>> depends on to whom you are explaining it.
> 
> The embedding is trivial:
> 
> (s p o) ---> s[p->o]
> 
> all the rest are just commentaries. This is why I feel that the semantics
> is not necessary.

You are forgetting the special treatment of all kinds of symbols (e.g.
blank nodes, ill-typed literals), as well as the embeddings of the RDF
and RDFS semantics.


Jos

> 
> 
> 	--michael  
> 
> 
>>>>> 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.
>>> You can put it this way, but then any embedding of any rule language into
>>> RIF can be viewed as a combined RIF-LanguageX language. Normally people
>>> will not view it this way.
>> The point is that RDF is not a rule language, but a data language. So,
>> people will want to exchange rules referring to RDF data sets.  The
>> agents receiving the rules and the data will have to *combine* them in
>> some way in order to process them.
>>
>> When exchanging any rule language using RIF, nothing will have to be
>> combined, so in this case (as you said) people will indeed not view it
>> as a combined language.
>>
>>
>> Best, Jos
>>
>>
>>>
>>>
>>> 	--michael  
>>>
>>>
>>>> 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/
>> ----------------------------------------------
>> The third-rate mind is only happy when it is
>> thinking with the majority. The second-rate
>> mind is only happy when it is thinking with
>> the minority. The first-rate mind is only
>> happy when it is thinking.
>>   - AA Milne

-- 
                         debruijn@inf.unibz.it

Jos de Bruijn,        http://www.debruijn.net/
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