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Re: [ontolog-forum] Ontology, Information Models and the 'Real World'

To: "Chris Partridge" <mail@xxxxxxxxxxxxxxxxxx>
Cc: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Sun, 15 Apr 2007 20:30:18 -0500
Message-id: <p06230907c2487957b939@[]>
>So, the thrust of my argument goes like this. If 
>we are modelling the domain, we need to look at 
>the domain.
>Is it true that every object in every domain has an identifier?    (01)

No. (The assumption that every thing has a name 
amounts to the 'substitutional interpretation' of 
the quantifiers, which has been thoroughly 
trashed and isn't viable. It doesn't even work 
for OWL.)    (02)

>I think not, so we need to accommodate objects without identifiers.    (03)

Well, we have to simply agree that such things 
can exist. It doesn't take much more than that to 
'accommodate' them. Some consequences might bite 
you, though, eg closed-world assumptions cannot 
be relied upon in general.    (04)

>Do identifiers exist in the domain? I think so.    (05)

Why not? They seem, like pretty simple things. 
But we have to allow people who aren't interested 
in them to ignore them.    (06)

>If they do, do we know what they are?    (07)

They are names, which are a subset of character 
strings. (In fact, I'd suggest, Unicode character 
strings, which allows a very wide-ranging kind of 
vocabulary, including things like Braille, 
LabaNotation and linear B).    (08)

>I think it is not clear that we do.    (09)

See above. Mind you, Im not saying that I know 
how to distinguish character strings which in 
some sense 'really are' names from other, merely 
accidental, character strings. But I don't think 
I need to, to allow them into the domain.    (010)

Our IKRIS project made a small start on this. In 
IKL, all character strings are in the domain and 
they are all 'potential' names. A string gets to 
be a name when it is used as one in the language, 
ie when it is used in a formula. For those, we 
have a special rule that relates the name's 
meaning to the name OF the name. Its very simple: 
if you give a character sting as an argument to 
the special function tnb (thing named by), its 
value is required to be whatever that character 
string would denote if you were to use it as a 
name. Formally,    (011)

(= (tnb 'name') name)    (012)

This is a very simple, elementary, basic rule, 
but it allows quite a lot to be done. For 
example, in IKL you can say that a list L of 
names is a 'closed world' for a predicate P by an 
axiom which quantifies over character strings:    (013)

(forall ((s charstring))(iff (P (tnb s))(ListMember s L)))    (014)

The fun part s that this kind of claim is usually 
assumed to require the use of a nonmonotonic 
logic, but the naming rule allows one to step 
around that kind of complication.    (015)

Pat    (016)

>I suspect this is enough to get our discussion going.
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