Dear Christopher, (01)
That is exactly the problem I mean, this kind of interpretation. (02)
> 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? (03)
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. (04)
MW: The usual language is that S3556 is installed as P101, indicating
temporary identity the two have. (05)
> There
> are the usual conventional ways in which the final S-P fact above can
> easily be given its 4D or temporal aspects. (06)
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? (07)
MW: It is certainly nothing to do with "a pump"/"the pump". (08)
Regards (09)
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/ (010)
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. (011)
>
> 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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