Dear Pat, (01)
> 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
> (4) in some time interval Matthew can be an instance of "Employee of
> Shell" and "Employee of Leeds U" (02)
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. (03)
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. (06)
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.
Both employee and person are subtypes of state_of_person. (07)
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). (08)
Reference Data Architecture and Standards Manager
Shell International Petroleum Company Limited
Registered in England and Wales
Registered number: 621148
Registered office: Shell Centre, London SE1 7NA, United Kingdom (010)
Tel: +44 20 7934 4490 Mobile: +44 7796 336538
> I need to be more specific. Another day or two for my
> more detailed
> reply to PatH.
> Patrick Cassidy
> MICRA, Inc.
> cell: 908-565-4053
> > -----Original Message-----
> > From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> > bounces@xxxxxxxxxxxxxxxx] On Behalf Of matthew.west@xxxxxxxxx
> > Sent: Tuesday, March 18, 2008 5:18 AM
> > To: ontolog-forum@xxxxxxxxxxxxxxxx
> > Subject: Re: [ontolog-forum] Ontology similarity and accurate
> > communication
> > Dear John,
> > > MW> So for example, there are ontologies where you will
> find employee
> > > > as a subtype of person, and others that understand it is not.
> > >
> > > I don't know which way you are advocating, but I'll summarize my
> > > position:
> > >
> > > 1. There is a fundamental distinction between natural
> types, such
> > > as Cat or HumanBeing, and role types, such as Pet or
> > >
> > > 2. Every instance of a role type is a subytpe of some
> natural type,
> > > but it may also be a subtype of other role types.
> > > HeartSpecialist
> > > is a subtype of Physician, which is a subtype of HumanBeing.
> > >
> > MW: I do mean that employee is not a subtype of person (or human
> > being).
> > MW: If we remind ourselves of what being a subtype means,
> it means that
> > each instance of a subtype is an instance of the supertype.
> Now ler us
> > look at an example. I am an employee of both Shell and Leeds
> > University.
> > I have different employee numbers, very different salaries, and
> > different start dates. Now if employee is a subtype of person then
> > each of these is a person, i.e. there are two of me.
> > MW: This kind of situation is true of roles generally, you can play
> > multiple roles at the same time and the same role multiple times
> > (and at the same time). These do not all generate new people.
> > MW: So the question is: what is the relationship between a role
> > and the person who plays is. Fortunately, as a
> 4-dimensionalist, there
> > is a simple answer. The role is a temporal part of the person that
> > plays the role, or if you prefer, the person for a period of time,
> > rather than for the whole of their life.
> > MW: This is not so different from the question of the vase and the
> > piece of clay. Are pots subtypes of clay? Or is the pot a different
> > object than the piece of clay it is made from?
> > Regards
> > Matthew West
> > Reference Data Architecture and Standards Manager
> > Shell International Petroleum Company Limited
> > Registered in England and Wales
> > Registered number: 621148
> > Registered office: Shell Centre, London SE1 7NA, United Kingdom
> > Tel: +44 20 7934 4490 Mobile: +44 7796 336538
> > Email: matthew.west@xxxxxxxxx
> > http://www.shell.com
> > http://www.matthew-west.org.uk/
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