- From: Mikael Nilsson <mini@nada.kth.se>
- Date: Wed, 15 Jun 2005 13:42:05 +0200
- To: Bernard Vatant <bernard.vatant@mondeca.com>
- CC: "Miles, AJ \(Alistair\)" <A.J.Miles@rl.ac.uk>, public-esw-thes@w3.org, "Dan Brickley (E-mail)" <danbri@w3.org>
- Message-ID: <42B0140D.5060203@nada.kth.se>
Hi! Let me try to add some comments... Bernard Vatant wrote: >>>_:node1 a:SKOS_representation eg:People >>>_:node1 a:RDFS_representation foaf:Person >>> >> >>(Playing devils advocate - I'm very grateful for this discussion :) ... >> >>In what way are the above statements any different from e.g. >> >> eg:People skos:it foaf:Person. > [...] > > In the blank node example, I don't express any direct relationship between the resources, > because IMO actually there is none. They both are representaions of some "ineffable > subject" which might live beyond/before any representation, but on which existence we > should keep agnostic they are both "fingers pointing at the moon", but somehow indicating > it. As I posted an hour ago on my blog, I came this morning to this surprising conclusion > : "subjects have no identity, only representations have one". Note that I say subject here > to refer to what TM folks used to call "non-addressable subject". So blank nodes are the > best way to "capture" implicitly this subject without identifying it to a resource, which, > I agree with what you wrote a few posts ago, would lead us to recursive definitions. Well, I think there are several issues with this argument. First, Alistair might define A skos:it B to mean: "B is the RDFS representation of the 'subject' that has A as SKOS representation". This shows that even though you might not perceive a direct relationship between the two, I can come up with a perfectly valid property to "shortcut" any indirect relation. Put another way, the existence of an intermediate node does not preclude the use a direct property to describe this relationship. Such a relationship can even be expressed in OWL and so inferred automatically... See below, however, for reasons for not wanting to do it using direct properties anyway. Second, you say "subjects have no identity". Unfortunately you contradict this by giving the (admittedly blank) subject node the (locally valid) identifier _:node1. You must look closer at the definition of "having identity". I believe one good definition is "being separable from other things". So if you are giving your subject a blank node, it is very much separable from other things. Indeed that is the very reason you create this blank node - to be able to *identify* the subject of your properties... If something does not have an identity, you cannot even use a blank node to refer to it (because that shows it has an identity!). > > Moreover, the blank node option allows you to gather as many resources as you want, be > they in a formal scheme or not. > > _:node1 a:SKOS_representation eg:People > _:node1 a:RDFS_representation foaf:Person > _:node1 a:Wikipedia_definition http://en.wikipedia.org/wiki/Person Now, this is an argument for using a separate node (blank or not). This is of course not doable using skos:it. However, is this needed? are there really N different paradigms? Is not the Wiki node compatible with SKOS concepts? So we would have only two domains. And I am still not entirely convinced that foaf:Person and ex:People are not identical (sameResource). What are the arguments that they are different? /Mikael -- Plus ça change, plus c'est la même chose
Received on Wednesday, 15 June 2005 11:42:29 UTC