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Re: [ontolog-forum] Requesting Opinions on the Benefits of Predicates as

To: ontolog-forum@xxxxxxxxxxxxxxxx
From: Tara Athan <taraathan@xxxxxxxxx>
Date: Tue, 17 Jun 2014 07:51:22 -0400
Message-id: <53A02BBA.9070907@xxxxxxxxxx>
On 6/17/14 1:03 AM, Pat Hayes wrote:
>> Using the IKL “that” operator and a “during” relationship and the concept 
>“July” (a ‘calendar month’):
> Whoa. No, this is NOT the right way to do it. In fact, this is meaningless. 
>According to the IKL semantics, (that (employs C P)) denotes a fixed 
>proposition which is true or false. There is no room for any time-dependent 
>variability in its truth value, or for making it depend on some other 
It may not be the *best* way to do it, but I don't agree that it's wrong 
or meaningless. Using the proposition (that (employs C P)) as an 
argument in a relation is not obstructed by its denotation of a fixed 
proposition which is true or false (in any given interpretation).    (01)

Starting off without quantifiers:    (02)

(cl:comment 'C employs P'
    (employs C P) )    (03)

(cl:comment 'It holds during time interval T that C employs P'
    (during (that (employs C P)) T )    (04)

Nothing wrong with that - the truth values of these sentences are 
independent of each other.    (05)

Now bring on the quantifiers to relate the two    (06)

(forall C P
     (cl:comment 'C employs P'
       (employs C P) )
     (exists T
(cl:comment 'It holds during some time interval T that C employs P'
         (during (that (employs C P)) T )
) ) )    (07)

Some users may find this clearer than the polymorphic representation. 
Why not let them use it?
It is still possible to have the polymorphic representation behind the 
scenes for reasoning purposes.
(forall C P T
(cl:comment 'It holds during time interval T that C employs P''
        (during (that (employs C P)) T )
(cl:comment 'C employs P during time interval T'
        (employs C P T)
) )    (08)

Also, using the "that" operator for temporal context is a gateway to 
using it for other contexts/modalities.
I find the symmetry appealing:
(cl:comment 'It holds before time interval T that C employs P'
    (before (that (employs C P)) T)
(cl:comment 'It holds after time interval T that C employs P'
    (after (that (employs C P)) T )
(cl:comment 'It is possible that C employs P'
    (possible (that (employs C P)) )
(cl:comment 'It is forbidden that C employs P'
    (forbidden (that (employs C P)) )
(cl:comment 'Jane believes that C employs P'
    (believes Jane (that (employs C P)) )
(cl:comment 'Omar knows that C employs P'
    (knows Omar (that (employs C P)) )
(cl:comment 'Maria asserts that C employs P'
    (asserts Maria (that (employs C P)) )
...    (09)

Tara    (010)

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