It may be useful to consider that a component is expressed in a language whilst
a part is expressed in technology. (01)
On Jan 29, 2012, at 12:15 PM, Matthew West wrote: (02)
> Dear Christopher,
>
> That is exactly the problem I mean, this kind of interpretation.
>
>> Does it not dissolve if you distinguish between SKU_S3556 as an actual
>> physical part, with its individual characteristics and history, on the
>> one hand, and on the other hand P101 as a virtual placeholder for a
>> pump, with its position, connections, physical requirements and system
>> functions. Then SKU_S3556 isInPlace P101. Not so?
>
> MW: The whole point is that a system component is not virtual. You can't
> kick something virtual. It is physical in the same way that the installed
> pump is, it just has a different pattern of existence, which seems to be
> beyond most ontologists.
>>
>> There is doubtless a more usual set of nouns and verbs that Mechanical
>> Engineers habitually use for such situations, but some such set of
>> categories or types seems a starter move in a workable direction.
>
> MW: The usual language is that S3556 is installed as P101, indicating
> temporary identity the two have.
>
>> There
>> are the usual conventional ways in which the final S-P fact above can
>> easily be given its 4D or temporal aspects.
>
> MW: In 4D it is a breeze. The system component consists of the temporal
> parts of the things installed whilst they are installed. You have both the
> pattern and the physicality required. In 3D you have to admit a new kind of
> particular.
>>
>> Or is the problem you've in mind deeper than merely the "a pump" / "the
>> pump" distinction?
>
> MW: It is certainly nothing to do with "a pump"/"the pump".
>
> Regards
>
> Matthew West
> Information Junction
> Tel: +44 1489 880185
> Mobile: +44 750 3385279
> Skype: dr.matthew.west
> matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
> http://www.informationjunction.co.uk/
> http://www.matthew-west.org.uk/
>
> This email originates from Information Junction Ltd. Registered in England
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> Registered office: 2 Brookside, Meadow Way, Letchworth Garden City,
> Hertfordshire, SG6 3JE.
>
>
>>
>> Regards,
>> Christopher
>>
>> ----- Original Message -----
>> From: "Matthew West" <matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx>
>> To: "'Ontology Summit 2012 discussion'"
>> <ontology-summit@xxxxxxxxxxxxxxxx>
>> Sent: Sunday, January 29, 2012 1:48 PM
>> Subject: [ontology-summit] System Components
>>
>>
>> Dear Colleagues,
>>
>> Last Thursday I complained that most ontologies do not give adequate
>> treatment to what I call system components, and if ontology is going to
>> gain traction within the systems world, it needs to get a better
>> understanding of this central idea in systems engineering.
>>
>> I illustrated the issue by telling the (simplified) life story of a
>> system component: the pump, P101, at the bottom of a distillation
>> column. Here is its story.
>>
>> The designer creates a drawing of the distillation column including at
>> the bottom of the column a pump to pump away the column bottoms. He
>> labels it P101, decides that one pump will be sufficient, and gives the
>> specification for the pump in terms of Net Positive Suction Head,
>> differential head, flow rate, materials of construction, and many other
>> things.
>>
>> The construction engineer picks up the drawing and specification and
>> notices he has to install a pump as P101. Fortunately, he has a pump in
>> stock from a previous project, that has been in stores unused for 5
>> years which exactly meets the specification. On it is stamped Serial No
>> S3556.
>>
>> The designer and the Operator comes to see the pump be installed, and
>> once the connections are made, he gives the pump a friendly kick and
>> says to the construction engineer "It's good to see P101 realized at
>> last". The construction engineer says in return "Yes, and it's good to
>> get S3556 off my hands at last." He turns to the operator and says "Why
>> don't we change your drawings to show S3556 instead of P101?" The
>> operator says "No, don't do that, it's a replaceable part, and one day
>> another pump will be put there, and I don't want to have to change all
>> the drawings and other documentation that refers to P101 each time it
>> is
>> replaced, as far as I am concerned it's the same pump whatever is
>> installed there."
>>
>> Some time later the pump breaks down and needs to be taken back to the
>> workshop. The maintenance engineer says to the operator "Hi, can I take
>> S3556 installed as P101 back to the workshop?" The operator replies
>> "Sure, but what am I supposed to do without my P101? If it does not
>> exist I cannot operate my distillation column." The maintenance
>> engineer
>> responds, "I understand. We have another pump S4567, that meets the
>> same
>> specification as P101. We'll replace S3556 with it and you will only be
>> without P101 for a few hours. I don't understand how you can continue
>> to
>> call it P101 though when all the parts have changed at once." The
>> operator replies "I don't care about that. What I care about is what is
>> connected in my system to pump the liquid from the bottom of the
>> column.
>> As long as it does that, it is P101 to me."
>>
>> Later the distillation column is demolished. The operator says, "A sad
>> end, I was very fond of P101, but it is no more." The demolition
>> engineer says, "Yes indeed. Fortunately, we can take S4567 and use it
>> on
>> another plant."
>>
>> It's probably worth summarising the key characteristics of a system
>> component:
>> - It comes into existence the first time it is installed.
>> - It is identical to the equipment items installed, whilst they are
>> installed (but not before or after).
>> - It can survive complete replacement of all its parts at once.
>> - It can survive periods of non-existence.
>> - It ceases to exist when the system it is a component of ceases to
>> exist.
>>
>> This is clearly rather different from the life of ordinary physical
>> objects. However, relatively few ontologies recognise that such things
>> exist. Many try to fob system components off as being classes, or
>> abstract individuals, though these clearly do not have the required
>> characteristics.
>>
>> Ontologists need to step up to the mark here and provide proper
>> recognition for system components.
>>
>> Regards
>>
>> Matthew West
>> Information Junction
>> Tel: +44 1489 880185
>> Mobile: +44 750 3385279
>> Skype: dr.matthew.west
>> matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
>> http://www.informationjunction.co.uk/
>> http://www.matthew-west.org.uk/
>>
>> This email originates from Information Junction Ltd. Registered in
>> England and Wales No. 6632177.
>> Registered office: 2 Brookside, Meadow Way, Letchworth Garden City,
>> Hertfordshire, SG6 3JE.
>>
>>
>>
>>
>>
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