Re: Southampton Pub data as linked open data

On 2008-07-30, Bijan Parsia wrote:

> For many reasons. I.e., I would recommend this even if subpropertying 
> rdfs:label becomes legit OWL DL.

I already know that you're one of the few people who're intimate with 
the logical details, so... Could you recap, after such an extensive 
discussion, *why* subproperties of rdfs:label (or any other property for 
that matter) aren't compatible with OWL DL?

>From what I can understand, either the relevant portion of the combined 
grammar will not be utilized in inference/rewriting, or it will and the 
results will agree higher up the ladder. The cinch would then be that 
there's something very special about the computational realization of 
RDFS semantics which would kill the nice termination properties of the 
inferencing process at the OWL DL level.

If I'm right, what is it that causes said problem? Or if I'm wrong, 
could you elaborate?

> """(rdfs:comment, rdfs:seeAlso, rdfs:isDefinedBy and rdfs:label are 
> included here because some constraints which apply to their use can be 
> stated using rdfs:domain, rdfs:range and rdfs:subPropertyOf. Other 
> than this, the formal semantics does not assign them any particular 
> meanings.)"""

They don't possess *formal* semantics, other than those assigned to them 
via application of rdfs:subPropertyOf and so on. So the pure formalists 
amongst the RDF/RDFS/OWL/DAML/whatever crowd would say *just* that.

That still doesn't mean said primitives possess *no* semantics at *all*. 
Their *formal* semantics are restricted to whatever derivative, 
inferential assertions they give rise to in combination with the rest of 
the asserted theory, to be sure. But they *do* still have their 
separate, hazy, intuitive, linguistic, common sense meanings/semantics.

The latter are also why they were included in the specification(s) in 
the first place: as a bootstrap that enables us to bridge the gap 
between the everyday meaning needed for actual application development 
(e.g. "me" in the human sense as opposed to the unique identifier 
"oid:1.3.6.1.4.1.12798.1.2049"), and the nitty-gritty of formal logic 
(e.g. me hasLittleBrother myLittleBrother). That bridge is quite 
obviously needed for any proper application of the technology, no matter 
how consistent, logical and machine processable it is down below.

I would also argue that that's why Tim would, in my mind, so much like 
to subclass rdfs:label for every kind of name: ideally a human software 
developer would like every kind of human readable label/name to present 
itself automatically to him. And what then is a human readable 
name/label but a subtype of the original, purposely included, singular 
RDF label "rdfs:label"? That what it was *meant* for, and the same goes 
for the rest of the "hazy" stuff like comments...

The real world denotations of those formal URI's are meant to document 
and distinquish certain central, useful, human intuitions about the 
concepts the RDF family of languages formally reasons upon. If we, for 
some formal reason, cannot subtype them, we'd be losing the logical 
unity of the framework, at least at the human readable level. I mean, 
two different kinds of labels/names? In the same language? What if some 
idiot declared both? What would I call my concept *then*?!?

>> 4. OWL people ask RDF people to stop subclassing these properties in 
>> order to meet the restrictions imposed by OWL-DL.
>
> Do whatever you want.

That is not a very constructive answer, in my mind. I'd rather see a 
consensus on what the problem is, and then a clean, mutually agreeable 
solution which adapts one -- or more likely both -- of the standards so 
that these sorts of clashes just cease to be. And *especially* at such a 
fundamental level as OWL DL: that wasn't supposed to be the 
specification that gives us the most trouble within the RDF family of 
formal languages. It was supposed to be the easiest and most useful. Now 
I'm already beginning to be disappointed...
-- 
Sampo Syreeni, aka decoy - mailto:decoy@iki.fi, tel:+358-50-5756111
student/math+cs/helsinki university, http://www.iki.fi/~decoy/front
openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2

Received on Wednesday, 30 July 2008 00:57:54 UTC