RE: Literals (Re: model theory for RDF/S)

>  > -----Original Message-----
>>  From: ext Graystreak [mailto:wex@media.mit.edu]
>>  Sent: 05 October, 2001 00:36
>>  To: www-rdf-logic@w3.org
>>  Subject: Re: Literals (Re: model theory for RDF/S)
>>
>>
>>  PFPS asserted:
>>  > If you can understand a specification like Corba or JTAPI
>>  or even the
>>  > meaning of a programming language, like C++ or ML, then you
>>  should be
>>  > able to work your way through a model theoretic
>>  specification.  After
>>  > all, RDF and DAML+OIL are a lot more simple than Corba or C++!
>>
>>  Speaking as a true naif here, no.  They're not.  I'm not at
>>  all sure what
>>  it means to "understand the meaning of a programming language."  To my
>>  knowledge, programming languages don't have meanings.  They're just
>>  syntactic sugars, in which programs are written.  Sometimes very smart
>>  people can figure out some formal semantics of some of those programs,
>>  provided the programs aren't even a little bit complex.
>>
>>  So when someone like me sets out to read and comprehend Patrick Hayes'
>>  "RDF Model Theory" document, it's bloody slow going.  (Thanks
>>  to Patrick
>>  for doing that work, btw.)
>>
>>  When those of us who are used to sitting down and building
>>  things try to
>>  wrap our brains around this RDF stuff it gets tricky.  It has
>>  these two
>>  weird properties in that it's all wrapped up in FOPL which we learned
>>  back in undergrad days was a formal system not connected to the real
>>  world.  And it's supposedly the way real knowledge is to be
>>  represented,
>>  such as business information, rules of operation, and so forth.
>>
>>  I still haven't figured out how to synthesize the two notions; I don't
>>  think I'm atypically stupid.  
>
>I'm glad someone else said it. I didn't want to feel *too* stupid all by
>myself...  (even if it's justified in my case ;-)
>
>Even though the MT is important, that's not what the "common folk"
>really need to apply RDF. What is *also* needed, as has been mentioned
>in this thread already, is one or more standardized APIs based on
>that MT which insulate the common folk from the really complex stuff, so
>that things can "just get done" ;-)

I agree. The point of the MT isn't really for those who are using RDF 
(except maybe as a kind of backup tome to settle any arcane 
disputes), but for those who setting out to write engines that 
propose to draw conclusions from RDF, or to answer queries in some 
as-yet-undefined RQF, or to interface RDF with some as-yet-undefined 
RDF-rules extension. And I wouldn't expect APIs which refer to the 
model-theoretic machinery at all; but I would expect APIs like, Check 
whether <this triple> is entailed by <this graph> with respect to 
<this reserved namespace> ; and the MT is simply a general-purpose 
spec for determining exactly what the key words like 'entails' 
actually mean. If you are using some engine and it gives you an 
answer that seems wrong to you, the MT provides a way to objectively 
settle whether it is or  not. It plays the same kind of role for 
entailment and inference that a BNF plays for parsing; its more 
complicated, but then inference *is* more complicated than parsing.

Pat Hayes
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Received on Friday, 5 October 2001 16:03:50 UTC