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

To: Waclaw Kusnierczyk <Waclaw.Marcin.Kusnierczyk@xxxxxxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Mon, 16 Apr 2007 09:22:52 -0500
Message-id: <p06230910c24934c8a751@[]>
>>  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,
>>  (= (tnb 'name') name)
>Clearly, but you either have to assume a single global context (for
>'name' to always denote the same entity),    (01)

I do assume a global context, yes. In fact, in 
IKL we assume no context at all. The logic simply 
isn't contextual, which IMO is the way the base 
logic should be for information interchange. So 
names are global, just as URIs are.    (02)

>  or, having admitted local
>contexts -- some sort of lexical or other scoping -- you leave way for a
>name to denote different entities.    (03)

If one wants to admit local name scoping - and we 
did need to do this for IKL - then the 
appropriate way to do it is to combine the 
context with the *quoted* name (not the name 
itself), and in IKL this is done by simply adding 
a context argument:
(tnb 'name' context1)
denotes the thing that 'name' denotes in 
context1. This handles referential opacity and so 
on very neatly.    (04)

>For example, you may have two contexts c1 and c2 such that (= (tnb
>'name') name) evaluates to true in both of them    (05)

That is meaningless in IKL. Contexts are objects 
in the domain, not entities in which sentences 
are evaluated. You are talking 'context logic' 
style. IMO context logic is a dead end. One of 
John McCarthy's rare blunders.    (06)

>, 'name' as in c1 =
>'name' as in c2 (trivially), yet name as in c1 != name as in c2.    (07)

(not (= (tnb s context1) (tnb s context2)))    (08)

where s is 'name'. Indeed, this situation can 
arise. But there are types of 'context', such as 
times and locations - parts of the 'real world' - 
which do not affect the meanings of names. In IKL 
these can be defined axiomatically:    (09)

(forall (x) (iff (transparentContext x)
                    (forall ((s charseq))(= (tnb s)(tnb s x)))
))    (010)

Pat    (011)

>Simply put:  the rule that 'e' should always mean e may be satisfied
>even if 'e' denotes different entities (on different occasions of use).
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