Ed, Pat C, William, (01)
EJB
> I find it amusing that John takes this stance on the Ontolog Forum,
> while on the Common Logic revision exploder, he is the apostle
> for a segregated dialect of CL, i.e., a logic in which 'relations'
> are not 'entities' (individual things in the universe of discourse). (02)
The term 'segregated' is not mine. It was put into the CL standard
of 2007. What I have been proposing is (a) get rid of it, or
(b) redefine it in terms of something simpler. In the recent
discussions, I proposed a classification of CL dialects in which
segregated dialects are just one among a wider range of options
that are definable in terms of the core CL semantics. (03)
JFS
>> A class is defined as a pair (t,s), where t is a monadic relation called
>> the type, and s is the set of everything for which t is true. (04)
PC
> It seems as though in this definition, if the relation "t" alone
> defines a class, then every class must be defined by both necessary
> and sufficient conditions ("the set of **everything** for which t
> is true"). (05)
In this example, I was using ordinary English. In the preceding example
of that note, I used FOL and said that the quantifier ranged over the
universe assumed for the ontology. (06)
PC
> But In many ontologies I have seen many classes are described by only
> necessary conditions. (07)
If the authors are being careful, they would state the assumed domain
(AKA universe of discourse). The domain + the type relation are the
necessary and sufficient conditions for determining the set. (08)
WF
> Nothing wrong with the word 'attribute', or the way CHEN and now
> everyone uses it.
>
> EXCEPT FOR Tthe BIG MISTAKE of thinking that a certain kind of thingie
> (say blue) IS an attribute, just because it **can play that role.** (09)
I agree. I would use a dyadic relation named HasAttr to relate
an entity to something called an attribute of that entity. (010)
An attribute of something is only an attribute when it is viewed
in the role of the second argument of a relation named 'HasAttr'. (011)
WF
> In another attibutive relation, the same thingie, blue, can play
> the role of attributed to, such as in 'blue is a color.' (012)
This raises the question about instances of blueness. We'd like to say
the blue of your coat is darker than the blue of the sky. So we need
to include instances of blueness in the ontology: the HasAttr relation
relates a coat x to an instance of blueness y, which we can relate to
another instance of blueness z of the sky. (013)
WF
> Did you ever have clients who had trouble seeing that 'customer'
> was a role, and that so was 'vendor,' so that the vendor and customer
> might be the same company? (014)
Good old Aristotle was quite clear about those issues. He
distinguished the "substance" -- such as HumanBeing -- from the
"accidents" such as being blue or being a customer, vendor, etc.
For an Aristotelian description of George Washington, see slide 6
of http://www.jfsowa.com/talks/aristo.pdf (015)
John (016)
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