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.

Sorry, but I must protest. They certainly do have meanings; some of 
them have elaborate formal semantics. There are libraries full of 
this stuff.

Now, do you need to read all this in order to write code?  No, of 
course not. But you do need to grok a basic understanding of the 
distinctions which are stated exactly in the more formal work; and a 
formal semantics is often a very useful resource for those who have 
to write the utilities that support the work of the everyday 
programmer.

>  They're just
>syntactic sugars,

That phrase refers to a sugar *coating*. There has to be something 
for the sugar to stick to, and if you are going to get anything done, 
it had better have a processor in it.

>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.)

(Do you mean to me for writing it, or Patrick Stickler for reading it? :-)

Its not a way of thinking that comes naturally until you are used to 
it, I will admit. We are working on a more tutorial document, with a 
kind of MT for Dummies included in it.

>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.

Aaarghhh!  You had bloody bad teachers, then.  This seems to be a 
common misapprehension, but its a really terrible one. Logic is often 
presented using things like P and Q , but that doesn't mean its not 
about anything; it means it's about EVERYTHING.  Do you think 
Aristotle was only thinking about letters?
Suggestion: toss the word 'ontology' at Google and read some of the 
stuff you find. Or take a look at the DAML-S ontologies. This is 
aggressively real-world stuff.

>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 could go on, here, but I think Peter
>himself pointed at the problem about a week ago, in a note to
>rdf-interest:
>	"I'm not happy at all with the fact that RDF has a 51 paragraph
>	document just to define what a literal is."
>
>Amen, brother.

OK, I will agree with that, but don't blame the logicians for that 
one. That is the result of an over-rapid blunderbuss standardization 
phenomenon, where the same words was simultaneously used by about 25 
different communities all of whom now have an investment in code that 
they want to have grand-fathered into backward compatibility.

Pat Hayes
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Received on Friday, 5 October 2001 15:52:35 UTC