Seem to me a pig is a pig that may fill the role of "doorstopric"
On Feb 1, 2012, at 9:08 PM, Cory Casanave wrote: (01)
> +1 for roles!
>
> Try this one - is a pig a doorstop? It is if it is holding open a door. The
>role and the "thing" may have very different descriptions yet describe
>different aspects of the same individual. The same thing could even be
>playing multiple roles or the same role in different context.
>
> Don't know why I like the pig thing, just always makes me smile!
>
> If 101 and S3556 were not both so related by name and "intended use" we would
>never confuse the role and the thing. So perhaps S3556 could be a doorstop as
>well! But pigs make poor pumps. The difference is another concept that makes
>for challenging formalization - capability.
>
> Perhaps a first-class concept of roles is missing from our toolbox?
>
> -Cory
>
> -----Original Message-----
> From: ontology-summit-bounces@xxxxxxxxxxxxxxxx
>[mailto:ontology-summit-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
> Sent: Wednesday, February 01, 2012 9:32 PM
> To: Matthew West
> Cc: Ontology Summit 2012 discussion
> Subject: Re: [ontology-summit] System Components
>
> Very good question, Matthew. Let me try out an idea on you. Your P101 is
>actually a role played by a pump, rather than a pump itself. Think of it as
>being like Hamlet, as played by Lawrence Olivier (P101 as played by S3556).
>You can change actors, and Hamlet is still Hamlet - same role - and while
>Olivier is playing the role, he *is* Hamlet, at least in a sense. But this
>second "is" cannot be identity, since you can kick the actor, but you can't
>kick a role.
>
> Both a pump and a pump-role are spatiotemporal entities, but they have
>different identity conditions. The identity of a pump, like any other physical
>object, is determined by the disposition of pieces of material stuff (metal,
>plastic, rubber), but the identity of the role is determined by its
>interfaces to the rest of the system (being connected to this pipe in this
>place and operated by this controller, etc..)
>
> You can identify a pump-phase (temporal slice) with a pump-role-phase, but
>you must not identify the actual individuals, so its safer to actually have a
>relation of 'functioning as' of the like to attach a role-playing thing to its
>role. Or, you can treat the role as a time-dependent property of the physical
>thing, but you will probably need a CL-style ability to have properties of
>properties if you go that (elegant) route.
>
> Make sense?
>
> Pat
>
>
>
> On Jan 29, 2012, at 3:48 AM, Matthew West wrote:
>
>> 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
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>> Registered office: 2 Brookside, Meadow Way, Letchworth Garden City,
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>>
>>
>>
>>
>>
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