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Re: regrets telecon on Tuesday

From: Axel Polleres <axel.polleres@deri.org>
Date: Mon, 21 Jan 2008 17:20:52 +0000
Message-ID: <4794D474.3090201@deri.org>
To: Hassan At-Kaci <hak@ilog.com>
CC: axel@polleres.net, Christian de Sainte Marie <csma@ilog.fr>, Jos de Bruijn <debruijn@inf.unibz.it>, RIF <public-rif-wg@w3.org>

Hassan At-Kaci wrote:
> Axel Polleres wrote:
> 
>> whereas, on the contrary in frames, any slot can appear 0 or several 
>> times, i.e.
>>
>> person1[firstname -> "Christian", lastname -> "de Sainte Marie"]
>>
>> and
>>
>> person1[firstname -> "Christian"] AND person1[lastname -> "de Sainte 
>> Marie"]
>>
>> say the exactly same thing, i.e. mutually entail each other.
> 
> What? You mean that there can be only one "person1" object named
> "Christian"? 

no, I mean whether I write the frame formula in version one or version 2 
above, it is the same thing. that has nothing to do with keys. person1
is the objectID ... maybe I should have written


person1##person[firstname -> "Christian", lastname -> "de Sainte Marie"]

and

person1##person[firstname -> "Christian"] AND person1[lastname -> "de 
Sainte
  Marie"]

to make this clearer.



> IMHO, what you are describing corresponds to the notion
> of database record key(s) - i.e., the attribute(s) that characterize
> individual records.
> 
> Furthermore, even if you do have a notion of keys (which we have
> not discussed within RIF as far as I recall), there is still another
> situation to take into consideration: just like algebraic (i.e.,
> positional) terms are built of symbols that may have (or not)
> well-formedness constraints (e.g., signatures, typing, annotations,
> etc...). To make things even more interesting, not everyone agrees
> with one specific semantics for the very same frame syntax (i.e., do
> we allow repeated "slots" - and in this case, is this an error or is
> it that such a slot has as value the set (or some kind of aggregate)
> of all the values for this slot. Some also allow mandatory as well
> as non-mandatory attributes - some even allow any symbol as a slot
> (i.e., unconstrained signatures).
> 
> While the RIF BLD masterminds (i.e., the authors of the document:
> Harold and Michael) give one possible semantics for these syntactic
> constructs; but this semantics is not necessarily compatible with
> many extant rule languages, several of which would wish to use the RIF.
> 
> -hak


-- 
Dr. Axel Polleres
email: axel@polleres.net  url: http://www.polleres.net/

rdf:Resource owl:differentFrom xsd:anyURI .
Received on Monday, 21 January 2008 17:21:12 GMT

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