Re: comparing XML and RDF data models

2008/7/2 Bijan Parsia <bparsia@cs.man.ac.uk>:
>
> On 2 Jul 2008, at 12:19, Mark Birbeck wrote:
>
>> Hi Tim,
>>
>> I'm not sure that this is where the differences lie.
>>
>> In my view the key point is that with RDF we have unique identifiers
>> for concepts--whether that is the things we're talking about, or the
>> vocabulary we're using to talk about them.
>
> [snip]
>
> I stop reading here.
>
> Here's why. At best we have unambiguous (not unique) identifiers and we
> don't have those either.

I don't think it is too hard in scientifically based/real world
ontology instances to determine whether things are infact unique or
common names for a universal thing.

> This isn't even a coordination issue. In a single ontology it's highly
> nontrivial to establish formal uniqueness (i.e., two names aren't
> equivalent/equal; requires lots of reasoning) and even harder to establish
> intended uniqueness (I might coin a term twice because I didn't recognize
> them to be the same).

Are you talking about establishing conclusively that two names are
definitely not referring to the same universal thing? With the open
world assumption you can never deny that they might refer to the same
thing, possibly in an inconsistent way according to the ontology, but
if you establish a consistent ontology and they do not match up given
your chosen reasoning rules then you have to make the best assumption
you can and say that they are not likely statistically to be the same
and run with that. RDF doesn't provide a solution to dirty data,
although it can be used to trace it better.

The point I think Mark may have been trying to make is that with
certain property combinations, InverseFunctionalProperty's can be
utilised in order to determine this uniqueness or non-uniqueness,
along with it being easier in RDF to distinguish between your
acknowledged terms, and outside terms, which in XML can result in you
not acknolwedging that two infoset elements are unique because one
contains an unknown namespaced property against the desires of one
schema, and you need to validate XML before you can work with it at
this level.

Cheers,

Peter

Received on Wednesday, 2 July 2008 22:03:08 UTC