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Re: [ontolog-forum] Fw: Thing and Class

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Patrick Cassidy" <pat@xxxxxxxxx>
Date: Sat, 6 Sep 2008 13:36:32 -0400
Message-id: <003901c91047$1a704ea0$4f50ebe0$@com>

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

 

Sean

 

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

have something like this

 

existent

    entity

        car

    characteristic

        part

            chassis

            engine

    proposition

 

But when the car is disassembled, it would look like this

 

existent

    entity

        chassis

        engine

    characteristic

        part

    proposition

 

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 -----

From: "Sean Barker" <sean.barker@xxxxxxxxxxxxx>

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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