- From: Jonathan Rees <jar@creativecommons.org>
- Date: Mon, 26 Jan 2009 16:51:40 -0500
- To: public-owl-comments@w3.org
SSFSS 9.5 "The SameIndividual assertion allows one to state that several individuals are all equal to each other, while the DifferentIndividuals assertion allows for the opposite — that is, to state that several individuals are all different from each other." If you have several individuals, they can't be equal to each other, since otherwise you'd only have one individual; and there is no need to state that several individuals are different, since otherwise there wouldn't be several of them, there would only be one. I think what you mean to say is that SameIndividual allows one to say that several individual *expressions* all refer to the same individual, or that several *apparently* different individuals are equal, or something like that. This is a symptom of a confusion throughout between the document expressions and what they refer to. A class is not an IRI, and yet you say Class := IRI. Now I realize that 'Class' (upper case) is defined formally to be a syntactic thing, and is not at all the same as a class, so while this is not to my taste (I would have called it a 'ClassName', paralleling 'ClassExpression') I can't really object to it. But the attitude is dangerous. I think I already pointed out a problem of this sort in the introduction. The treatment of "anonymous individuals" is also very confusing. First of all, members of the AnonymousIndividual class are not individuals, they are syntactic things denoting individuals. Second, in what sense are the individuals anonymous? The nodeid sure looks to me as if it is a name for the individual, albeit a local one that is not an IRI. You could take "name" = "nym" as a term of art meaning "IRI", so that nodeids do not qualify as names, but this seems a stretch. Rather than define "name" or "anonymous" technically, I think it would be easier to just create a new technical term for this syntactic category such as 'blank' or 'blank individual name' or 'local name' or 'node id'. The construction "with anonymous individuals renamed" in section 11 is especially disturbing, since it says directly that anonymous individuals have names. There is similar usage in 3.4. 5.6 "Individuals represent actual objects from the domain being modeled. There are two types of individuals in OWL 2. Named individuals are given an explicit name that can be used in any ontology in the import closure to refer to the same individual. Anonymous individuals are local to the ontology they are contained in." Because of SameIndividual, a single individual can be both "named" and "anonymous". The error here is confusing the individual with the name of the individual (the Individual). What you mean to say is that individuals can be named (or designated) in either of two ways, using an Individual (or I would say IRI or IndividualName) or using a node id; or neither, or both. Named vs. anonymous is a partition of the syntactic space of Individuals, not of the space of individuals. Best Jonathan
Received on Monday, 26 January 2009 21:52:19 UTC