Re: No universal things Re: comparing XML and RDF data models

On 3 Jul 2008, at 10:52, Bernard Vatant wrote:

>>> [Bijan] I don't know what a universal thing (is).
>>>
>>
>> [Peter] Sorry, I thought that would be obvious. In my realist view  
>> there are
>> things that people are trying to describe using RDF and those things
>> have identities, which we are labelling with names, or describing
>> through identifying properties. These are universal things. If you
>> want to establish equality you are likely to be doing it at this
>> level, unless you assume that markup is everything and a thing is  
>> only
>> in existence because there is a description of it, and the  
>> description
>> of the thing causes the thing to exist.
>>
> Peter, sorry to be as harsh on that as Bijan has been, but I  
> consider this viewpoint as not sustainable, and dangerously naive.
>
> I for one assume very strongly indeed that 'the description of the  
> thing causes the thing to exist', and my hunch is that Bijan will  
> follow me on this (at least I hope so).
[snip]

My official position, scarily enough, is that you don't need a  
definite metaphysical view in order to build good ontologies ;)

I do think that the family of views in computational ontologies  
generally called "realist" is indeed naive and fundamentally wrong  
headed. Whether it's a "useful fiction" that helps people write  
better or more compatible ontologies is an open empirical question.

But I, for one, wouldn't bet on it.

(I kinda wish it were...then we'd have realism justified as a useful  
fiction and it doesn't get better than that :))

Interestingly, we've had three sorts of claim about RDF that tries to  
support the "xpath is too structure sensitive"):

1) RDF just has the kind of structure for which this doesn't happen  
(that seems to be the original claim, plus some "it's easier to  
explore")
2) RDF is Python to XML's Perl. The strong version is that RDF really  
only has One Way to Say It. The weaker claims is that RDF encourages  
standard ways to say it or has fewer ways to say it.
3) RDF aligns with reality (or better with reality) thus ends up with  
reasonably similar models.

(Argh. These are more than a bit facile. I'm trying to sloganize to  
get the feel for different positions. Please don't take these as my  
full account of the various perspectives.)

What's strange about all of them is that they are conceptual  
arguments, almost purely and simply. I remember a class I co-taught  
at UMD. CS graduate students interested in AI. They had an assignment  
to write 20 things about themselves (in English) and then translate  
them into OWL.

I would bet that there was more convergence on *content* than on how  
to represent that content!

I remember also a project where we were trying to get people to write  
simple triples. They got that they needed triples. But what they  
ended up putting into the tool was things like

S       		P 	     O
"The cat is" "on the" "mat".
"Mary eats" "pudding" "on toast"

They just split up the sentences into somewhat equal parts!

None of this is to say that there aren't differences and benefits  
worth exploring. But representation is *hard*. Using representations  
is *hard*. Evolving systems with representations and queries is  
*hard*. We hope to make all this easier, but there really is no  
semantic bullet.

Cheers,
Bijan.

Received on Thursday, 3 July 2008 13:43:14 UTC