Pat Hayes wrote:
>> PH:
>>
>>> 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),
>
> 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.
>
>> or, having admitted local
>> contexts -- some sort of lexical or other scoping -- you leave way for a
>> name to denote different entities.
>
> 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.
>
>> For example, you may have two contexts c1 and c2 such that (= (tnb
>> 'name') name) evaluates to true in both of them
>
> 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. (01)
I was thinking about syntactic contexts, syntactic closures, as
first-class objects. Within each closure, clearly, 'x' (a name) means x
(the denotation of 'x' in that context). Across closures, though, the
meaning of 'x' may be different. (02)
In this sense, your (tnb name context) is equivalent to looking up the
specified closure for the name's entry, and (tnb name) is implicitly
using the closest closure (do you allow hierarchically nested contexts?) (03)
Whatever the relation to McCarthy's dead idea, let it be. (04)
>
>> , 'name' as in c1 =
>> 'name' as in c2 (trivially), yet name as in c1 != name as in c2.
>
> In IKL:
> (not (= (tnb s context1) (tnb s context2)))
>
> 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:
>
> (forall (x) (iff (transparentContext x)
> (forall ((s charseq))(= (tnb s)(tnb s x)))
> )) (05)
Yes, if (tnb s) is equivalent to (tnb s the-global-context), with
the-global-context being the global context, rather than (tnb s) being
eqivalent to (tnb s (the-current-context)), with the-current-context a
function returning the current context. (The latter case qould still be
ok if the statement above is made within the global context.) (06)
vQ (07)
>
> Pat
>
>
>>
>> Simply put: the rule that 'e' should always mean e may be satisfied
>> even if 'e' denotes different entities (on different occasions of use).
>>
>> vQ
>>
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>
> (08)
--
Wacek Kusnierczyk (09)
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Department of Information and Computer Science (IDI)
Norwegian University of Science and Technology (NTNU)
Sem Saelandsv. 7-9
7027 Trondheim
Norway (010)
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