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Patrick
You are quite right, it is the instances that
I reclassified from "part" to
"entity".
Dick McCullough Ayn Rand do speak od mKR done; mKE do enhance od Real
Intelligence done; knowledge := man do identify od existent
done; knowledge haspart proposition list; http://mKRmKE.org/
----- Original Message -----
Sent: Saturday, September 06, 2008 10:36
AM
Subject: Re: [ontolog-forum] Fw: Thing
and Class
Richard,
As you note, one may take different views of individual entities different
times, or even have multiple ways of classifying something at the same
time. But no matter how many different views one may want to take, the
type hierarchy should remain the same. In your example below, it was not
clear whether the terms ?car? ?chassis?, ?engine? were being used as
instances of such things, or were actually types in the hierarchy. If
the latter, modifying the hierarchy to adapt to different views is likely to
lead to utter chaos.
The better tactic is to include all variant views in the same hierarchy, and,
when communicating a representation, indicate which view is being used.
Unless the views are logically incompatible, they should be translatable into
each other, so that either view may be used by any
application.
When discussing ?parts?, if one wants the machine to do automated inferencing,
it is important to decide whether a ?part? is essential, in which case the
whole does not exist without the part, and if essential, whether it can be
removed from its functioning location in the whole and still be considered a
?part? of that whole. It is perfectly reasonable to disassemble a car in
a garage, and still say that ?the car is in the garage?. But that is a
convention that one must decide on when creating an ontology and an
application that uses it.
In order to represent such nuances, I find that multiple ?part? subrelations
are useful, each meaning something different.
A
general issue in creating relations is to decide whether it is an
instance-level relation or a type-level relation. In the latter case,
one might want to say. e.g. that every living human has a brain ? which
is different from saying that some specific human has a brain.
Being very explicit is necessary when the ontology is to be used for
automated reasoning.
Pat
Patrick
Cassidy
MICRA,
Inc.
908-561-3416
cell:
908-565-4053
cassidy@xxxxxxxxx
From:
ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Richard H.
McCullough
Sent: Saturday, September 06, 2008 10:40 AM
To:
[ontolog-forum]
Subject: Re: [ontolog-forum] Fw: Thing and
Class
I have
one remaining question -- what does your
concept
hierarchy look like?
In my
tabula rasa hierarchy, parts are characteristics
of the
entity that they are a part of. So you might
But
when the car is disassembled, it would look like
this
Thus my
concept hierarchy - my point of view -
changes
with
time, as the parts are assembled or disassembled.
In your
case, I would think the designers, manufacturers,
sales
personnel, etc. would have different
hierarchies.
Dick
McCullough
Ayn Rand do speak od mKR done;
mKE do enhance od Real
Intelligence done;
knowledge := man do identify od existent
done;
knowledge haspart proposition list;
http://mKRmKE.org/
-----
Original Message -----
Sent:
Saturday, September 06, 2008 3:44 AM
Subject: [ontolog-forum] Fw:
Thing and Class
>
> Dick,
>
> In engineering practice (at least as described
through ISO
> 10303), a part is either an inseparable component or an
assembly. An
> assembly consists of sub-assemblies (which are
assemblies) and
> components. The definition of assembly is
recursive.
>
> A product is a part. In ISO 10303, a part is a
subtype of a
> product, and this is quite distinct from a product
concept. Thus, a
> product concept might be "Range Rover", a four-wheel
drive vehicle,
> which is delivered as physically as a part
RR1-801/1, or RR1-801/2, or
> RR1-803/1, or RR1-805/1, or RR2-810/1,
etc, where in RRx-yyy/z, the RRx
> is the generic part number, the yyy
is the manufacturing assembly suffix
> and the /z is the version number.
In theory, all parts with the number
> RR1-801/1 are completely
interchangeable, and should be interchangeable
> with parts R1-801/2
(which differs from R1-801/1 in matters not
> affecting form, fit or
function), however will have some form, fit or
> function difference
from RR1-803/1.
>
> The occurrences of the Range Rover concept
will also be stamped
> with a serial number. A typical maintenance
manual will inform you of
> changes made in the product standard in
terms of the serial numbers that
> the change effects - e.g. from
1-100,000 it has a 2.3 litre engine, and
> from 100,001 onwards the
vehicle has a 2.5 litre engine. In practice,
> minor changes which
internally generate new part numbers will not be
> exposed at the level
of the maintence manual.
>
> Of course, the real situation is
rather more complicated, but in
> matters of detail, rather than of
substance (in the context of this
> discussion).
>
> The
point being, that a change approval creates a commitment to
> create a
new part (car, wheel, bolt, etc) which is either a revision of
> an
existing part (form, fit, function interchangeable) or a new part. In
>
the case of an assembly, this may be because it incorporates a new
part,
> or a new combination of existing parts. Conversely, creating a
new
> component part has no effect on end product unless it is embodied
in the
> chain of assemblies which contributes to an actual part (end
product),
> which in turn requires that a new version of these
assemblies is
> produced.
>
> The issue "is a
representation of" versus "is-a" versus
> "is-an-instance-of" is a
question of how we ground these relationships
> and how we ground the
concept of part. I ground the concept "part" as a
> "form, fit, and
function equivalence relation", such that two part
> designs (which
specify the part) are equivalent if the physical part
> they specify is
form, fit and function interchangeable. This means that
> the physical
parts are an instance of the class "part", and that a
> design is a
specification for the part. That is, the meaning of the
> concept "part"
is grounded in the results of using individual parts.
> Consequently, a
design office designs many parts, some of which are
> instantiated by
the manufacturing department as physical parts. In the
> design office,
parts instantiate the design process outputs, and are
> treated as
separate individuals, while in the manufacturing world, a
> part is a
class for producing physical parts.
>
> I hope this answers the
question.
>
>
> Sean Barker
> Bristol, UK
>
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
>
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Richard
H.
> McCullough
> Sent: 05 September 2008 11:24
> To:
[ontolog-forum]
> Subject: Re: [ontolog-forum] Thing and Class
>
> Sean & Dan
>
> It is hard for me to understand what
this discussion is about.
> When I see things
like
> part is described by
design
> and
> part is instance of
design
> I wonder if you are missing the whole concept
of
> part is part of design
> i.e., the
part-whole relation.
>
> In Sean's last email, time dependence is
mentioned, and I wonder -- are
> you now talking about a part-whole
relation which is time-varying?
>
> Dick McCullough
> Ayn
Rand do speak od mKR done;
> mKE do enhance od Real Intelligence done;
knowledge := man do identify
> od existent done; knowledge haspart
proposition list; http://mKRmKE.org/
>
> ----- Original
Message -----
> From: "Sean Barker" <sean.barker@xxxxxxxxxxxxx>
> To: <ontolog-forum@xxxxxxxxxxxxxxxx>
> Sent: Friday,
September 05, 2008 12:25 AM
> Subject: [ontolog-forum] Fw: Fw: Thing and
Class
>
>
>>
>>
>>
Dan,
>>
>> While I would agree that, say, the CAD model for
a part
>> describes the shape of a part, the issue is not one of
design but of
>> configuration management. In particular, the
criterion for being a
> part
>> A123 is that it is fit, form
and function identical to the "typical
>> part" A123. The design is
an "ontological commitment" that some class
> of
>> thing
exists (will exist). To reject this is to reject the concept of
>>
"is-a" and of labelling things with the concepts they
instantiate.
>>
>> Conversely, penguins do not stop being
penguins just because some has
>> sequenced their DNA (written down
their design).
>>
>> The fact that engineering systems are
concerned with coming-to-be and
>> ceasing-to-be suggests
that
>> engineering ontologies must use a temporal logic. In fact,
many
>> engineering
>> systems
>> are based on
effectivities and change notices. The first explicitly
>> identifies
what components
>> make up a product at a particular time or at a
point in the product
> run,
>> while th second
>>
controls when the definitions are changed.
>>
>> Sean
Barker
>> BAE SYSTEMS - Advanced Technology CentreBristol,
UK
>>
>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
>>
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Dan
>
Corwin
>> Sent: 01 September 2008 19:46
>> To:
[ontolog-forum]
>> Subject: Re: [ontolog-forum] Fw: Thing and
Class
>>
>>
>>
*** WARNING ***
>>
>> This mail has originated outside your
organization, either from an
>> external partner or the Global
Internet.
>> Keep this in mind if you answer
this message.
>>
>> No magic here, just typical abstract and
concrete objects.
>>
>> Sean Barker
wrote:
>>
>>> 2) The product of a design office is
designs, instances of the
> general
>>
>>> mathom
"design". In the DO, any class/type structure applied to a set
>>>
of designs is a generalization of the set of design instances
-
>>> designs are
>> > not classes for
anything.
>>
>> A "design" is surely an object in the world
of information.
>> It describes something, which you portray below as
concrete.
>>
>>> The product of a manufacturing
organization is parts, each of
>> > which is an instance of a
design.
>>
>> Wrong. Each "part" may be based on the
"design", but their
>> relation is described/describes, not
instance/class.
>>
>> regards,
>> Dan
Corwin
>>
>
>
>
>
>
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