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Re: [ontolog-forum] Ontology similarity and accurate communication

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Tue, 18 Mar 2008 15:48:50 -0500
Message-id: <p0623091ac405d99e2bfa@[]>
At 6:41 PM +0000 3/18/08, <matthew.west@xxxxxxxxx> wrote:
>Dear Pat,
>>     This is a good issue, but I think it has a resolution
>>  without the problem
>>  you envision, because in 3D the types of an entity can change
>>  with time.
>>    (1) employee is a role, which means that it must be time indexed.
>>    (2) every instance of employee (in some time interval) is
>>  an instance of
>>  person  (in that time interval)
>>    (3) a person can be an instance of multiple roles in any given time
>>  interval
>>    (4) in some time interval Matthew can be an instance of "Employee of
>>  Shell" and "Employee of Leeds U"
>MW: What you are missing is that EACH instance of employee MUST be a
>separate person if employee is a subtype of person. To put that the
>other way round, if I am just one person and there is an employee
>subtype of person, then I either am or am not an instance of employee,
>but I can only be an instance of employee once.
>MW: If you think that a Person can be more than one employee, then the
>relationship between person and employee is something other than
>MW: If I were a 3D-ist then I would suggest somthing like a consists of
>>    In 4D, I believe that the 4D worms will intersect, and that
>>  is another way
>>  of viewing the same thing, but it is only inconsistent if one
>>  assigns the
>>  same type "Person" to a 4d object in one ontology and a 3D
>>  object in the
>>  other, and then tries to use the same term to represent the
>>  two different
>>  types.
>MW: In 4D it is quite clear, and employee is a state of a person,
>and the relationship between person and employee is temporal part of.    (01)

Hmm. Consider a case where someone accepts a 'dual appointment' which 
comprises (say) a chair and the directorship of an institution, and 
these two, although conceptually distinct, happen to coincide exactly 
in time (they commence and cease at exactly the same moments). Such 
cases do happen. Doesnt this reproduce in 4-d the problem that arises 
in 3-d?    (02)

>Both employee and person are subtypes of state_of_person.
>MW: The interesting thing about temporal part of is that most
>properties are inherited by substates (except for example being
>a person for the whole of their life).    (03)

Yes. One thing I noticed a long time ago is that for very many 
ordinary purposes, one can treat a 4-d entity (and of course its 4-d 
parts) as identical to the 4-d spacetime envelope it occupies. Cases 
like the vase vs. the glass it is made of are supposed to be 
counter-examples, but they rarely are in practice. A real 
counterexample might be a plastic object which is made in a process 
which also creates the plastic itself (say by polymerization) and is 
destroyed by fire; but it takes some work to even think of cases like 
this.    (04)

PatH    (05)

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