-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Patrick Cassidy
Sent: Wednesday, March 19, 2008 2:36 AM
To: '[ontolog-forum] '
Subject: Re: [ontolog-forum] Ontology similarity and accurate communication (01)
Matthew,
If one were to attempt to create instances of a 3D Person that were also
instances of a role, the multiplicity you refer to would be a problem. In
the illustration below, Matthew is an instance of 3D Person, not an instance
of Employee - if Matthew were an instance of Employee, the problem you
describe would then present itself. But we can create instances of Role
such as an Employee that have a Person as a filler. Nevertheless the *Role*
"Employee" is also a subtype of Person, therefore an instance of an Employee
is always an instance of a Person, implicitly though not explicitly. (02)
<CL> The problem here is that "Employee" isA "Role" and a "Role" is NOT a
type of person. It isA "Social Relation" or such and modeling it as a person
will lead to problems as you suggest, but this is a problem because of the
modeler, not the model. This makes the rest of the argument difficult to
follow.</CL> (03)
But
the instances of a Role such as Employee are more like time slices and are
not identical to the instance of Person that fills the role. The
multiplicity is in the multiplicity of TimeSlices, as there are in a 4D
representation; every different TimeSlice is a different entity. The way
that can work is illustrated below using OWL.
One comment I made was not phrased properly:
[PC] > > (3) a person can be an instance of multiple roles in any given
time
> > interval
It would more accurately have been phrased that:
(3a) an instance of Person can fill multiple roles in any given time
frame
(3b) a timeslice of Person can be an instance of multiple roles
(3c) an instance of Role in any given time interval can be an instance of
Person - because Person and Role are not disjoint.
The illustration below should clarify what that means. (04)
Perhaps the non-intuitive element is that an instance of a Role (a
TimeSLice) can also be an instance of a Person(a dimension-neutral Type) -
because the type Person is not disjoint with the type TimeSlice. In the
illustration below, Matthew is a Person, but the instance
MatthewAsEmployeeOfShellAndLeeds is a Role - and also an instance of Person
- but is not identical to Matthew. It is more like a TimeSlice of Matthew.
Even So, Matthew is not necessarily 3D or 4D, Matthew is a dimension-neutral
entity.
If one were to use a formalism that permitted relation arities higher than
two, it would be possible to specify roles and their time limits without
using time slices. TimeSlices (among which are Roles) are syntactically
convenient when using OWL, they aren't logically necessary. They have the
same logical effect as an explicit time-indexed assertion on a
dimension-neutral entity. In that case, there would be no TimeSlices, only
time-indexed assertions (which are logically equivalent, after translation,
to assertions on TimeSlices). The axioms to translate the two formalisms
are not here because this is a pure OWL representation. (05)
All instance of Role should have start and end times specified - they are
time slices.
Person is in this case neither exclusively 3D nor 4D - time slices can be
generated by making a person an instance of 'TimeSlice', or an instance of
Role, which is a subtype of TimeSlice. Every TimeSlice has a start time and
end time.
But an instance of Person can also have attributes and relations specified
by explicit time-indexed relations, without using TimeSlices. (06)
In the following note that an Employee is a Role, and something can be an
instance of an Object as well as a Role.
(definitions - some parts are from Cyc - are abbreviated). (07)
HumanRole is a subtype of Person and Role
Every HumanRole is a Role whose RoleFiller is a Person (restriction)
PersonWithOccupation is a subtype of HumanRole (08)
<owl:Class rdf:ID="Employee">
<rdfs:comment>A Person who was employed by another Agent in some
hiring event.</rdfs:comment>
<rdf:type rdf:resource="#PersonType"/>
<rdf:type rdf:resource="#RoleType"/>
<rdfs:subClassOf rdf:resource="#TemporaryRoleCreatedByEvent"/>
<rdfs:subClassOf rdf:resource="#PersonWithOccupation"/>
<rdfs:subClassOf>
<owl:Restriction>
<owl:onProperty>
<owl:ObjectProperty rdf:about="#isEmployedBy"/>
</owl:onProperty>
<owl:someValuesFrom rdf:resource="#IntelligentAgent"/>
</owl:Restriction>
</rdfs:subClassOf>
</owl:Class> (09)
**** NOTE that 'employee' is a subtype of 'Person' **** (010)
<owl:Class rdf:ID="EmployeeOfShell">
<rdfs:subClassOf rdf:resource="#Employee "/>
<rdfs:comment>A person who is an employee of Shell.</rdfs:comment>
</owl:Class> (011)
<owl:Class rdf:ID="EmployeeOfLeeds">
<rdfs:subClassOf rdf:resource="#Employee "/>
<rdfs:comment>A person who is an employee of Leeds.</rdfs:comment>
</owl:Class> (012)
<!-- Matthew is employee of Shell from 1990 to 2008
Matthew is employee of Leeds from 1980 to 2004
--> (013)
<Person rdf:ID="Matthew"/> (014)
<EmployeeOfShell rdf:ID="MatthewAsEmployeeOfLeedsAndShell">
<rdf:type rdf:resource="#EmployeeOfLeeds"/>
<hasRoleFiller rdf:resource="#Matthew"/>
<rdfs:comment>Matthew is an Employee of Both Shell and Leeds from
the beginning of
1990 to the end of 2004.</rdfs:comment>
<hasStartingTimePoint rdf:ID="DTEG19900101T0000"/>
<hasEndingTimePoint rdf:ID="DTEG20041212T2400"/>
</EmployeeOfShell > (015)
Pat (016)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (017)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of matthew.west@xxxxxxxxx
> Sent: Tuesday, March 18, 2008 2:42 PM
> To: ontolog-forum@xxxxxxxxxxxxxxxx
> Subject: Re: [ontolog-forum] Ontology similarity and accurate
> communication
>
> 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
> subtype/supertype.
>
> MW: If I were a 3D-ist then I would suggest somthing like a consists of
> relation.
>
> >
> > 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.
> 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).
>
>
> 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/
>
> >
> > I need to be more specific. Another day or two for my
> > more detailed
> > reply to PatH.
> >
> > Pat
> >
> > Patrick Cassidy
> > MICRA, Inc.
> > 908-561-3416
> > cell: 908-565-4053
> > cassidy@xxxxxxxxx
> >
> >
> > > -----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
> > Employee.
> > > >
> > > > 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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