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[ontolog-forum] Fw: Thing and Class

To: <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Sean Barker" <sean.barker@xxxxxxxxxxxxx>
Date: Sat, 6 Sep 2008 11:44:32 +0100
Message-id: <000501c9100d$8c32d290$a3db6a58@PackardDesk>

Dick,    (01)

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.    (02)

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.    (03)

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.    (04)

Of course, the real situation is rather more complicated, but in
matters of detail, rather than of substance (in the context of this
discussion).    (05)

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.     (06)

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.    (07)

I hope this answers the question.    (08)

Sean Barker
Bristol, UK    (09)

-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Richard H.
Sent: 05 September 2008 11:24
To: [ontolog-forum] 
Subject: Re: [ontolog-forum] Thing and Class    (010)

Sean & Dan    (011)

It is hard for me to understand what this discussion is about.
When I see things like
    part is described by design
    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.    (012)

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?    (013)

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/    (014)

----- 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    (015)

> 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
> A123 is that it is fit, form and function identical to the "typical
> part" A123. The design is an "ontological commitment" that some class
> 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
> 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
> 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
>> 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
>    (016)

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