Pat, (01)
The direct/indirect distinction was raised by Matthew and can be found in
ISO 15926. Matthew or David can give you the latest links if you cannot
google it. (02)
It is part of an ongoing discussion elsewhere on the list ... e.g.
--- (03)
Matthew W: "Could you give me a unit (or two) that you think only applies to
one kind-of-quantity, and I'll see if I can identify another? (04)
IJ-answer: m (length), kg (mass), and t (duration).
--- (05)
The issue is, as you have indicated, one about the scope of the UoM
ontology.
This question of 'indirect' units was being discussed and I (assuming that
this meant it was an 'allowed' topic) commented on it. Was I mistaken? So, I
made no judgment about whether it is in our scope (your question seems to
imply I did) - I'll let you guys argue about that. (06)
However, if I was asked to make such a judgement I would say that it is a
difficult call. With the direct units it is reasonably easy to say how these
should be used. For indirect properties it is more difficult, but much more
useful. The engineers I have worked with would like to find some kind of
answer other than rule of thumb. A substantial proportion of the quantities
measures in their datasheets are 'indirect'. So, for them, the distinction
is important. (07)
If one does include them in, one of the problems is the sheer number of
indirect relationships and the lack of organisation. I think there is some
work to be done on explaining / understanding / unbundling the indirect
relationship if one wishes to get a reasonably general set of rules. (08)
> Well, indeed. But surely this notion of proper operation is not part
> of an ontology of units and quantities, even if that is understood to
> cover issues of how quantities are measured. (09)
So, if one would like some general classification of indirect units, my
guess is that it will be. (010)
Regards,
Chris Partridge
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> -----Original Message-----
> From: Pat Hayes [mailto:phayes@xxxxxxx]
> Sent: 30 September 2009 23:50
> To: uom-ontology-std; Chris Partridge
> Subject: Re: [uom-ontology-std] What is mass?
>
> Chris, before proceeding, could you please tell us what you mean by a
> 'direct' property, and why you feel that this direct/indirect
> distinction is relevant to our main goal here of formalizing an
> ontology of quantities and units.
>
> Pat Hayes
>
> On Sep 30, 2009, at 5:30 PM, Chris Partridge wrote:
>
> > Gunther,
> >
> > Your examples seem to agree with my point that indirect properties are
> > different from direct ones.
> > And I see you cash out the indirect property as a state (the option
> > I noted
> > in my original email).
> >
> > In your example, as far as I can ascertain, you describe observing a
> > direct
> > temperature, but you stipulate an indirect temperature - e.g. the
> > "Maximum
> > operating temperature of Machine X" rather than observing or
> > measuring it.
> > My guess is that there is more than mere stipulation involved here.
> > One of things your example does not capture is what operating properly
> > entails.
>
> Well, indeed. But surely this notion of proper operation is not part
> of an ontology of units and quantities, even if that is understood to
> cover issues of how quantities are measured.
>
> One can play this game of 'you havn't captured X' for ever.
> Eventually, it will always become circular.
>
> Pat
>
> > Typically there are quite a few ceteris paribus conditions, which
> > are not mentioned here (or are implied by the use of the phrase "act
> > of
> > operating properly").
> >
> > I'll leave it to the engineers to provide examples of scale
> > properties of
> > temperature.
> >
> > Regards,
> > Chris Partridge
> > Chief Ontologist
> >
> > Mobile: +44 790 5167263
> > Phone: +44 20 81331891
> > Fax: +44 20 7855 0268
> > E-Mail: partridgec@xxxxxxxxxxxxxxx
> >
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> >
> >> -----Original Message-----
> >> From: uom-ontology-std-bounces@xxxxxxxxxxxxxxxx
[mailto:uom-ontology-std-
> >> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Gunther Schadow
> >> Sent: 30 September 2009 22:54
> >> To: uom-ontology-std
> >> Subject: Re: [uom-ontology-std] What is mass?
> >>
> >> Chris Partridge wrote:
> >>> They seem to be like Cambridge properties, in as much as it is not
> >>> clear
> > how
> >>> mere examination of the object will reveal (the value of) the
> >>> property.
> > So
> >>> some kind of explanation of the relation is needed to understand it.
> >>>
> >>> At the practical engineering level, the normal interpretations of
> >>> scale
> >>> operations such as addition (e.g. in the case of mass, putting both
> > objects
> >>> with the mass on the same scale) and so on do not seem to work in
> >>> the
> > same
> >>> way.
> >>
> >> This only works for extensive properties. It fails with temperature
> >> already. So that aspect does not seem to make a difference between
> >> maximum allowable temperature and actual temperature.
> >>
> >> To me "maximum allowable temperature" is the upper bound of the
> >> "operating temperature" interval, which in turn is a criterion over
> >> the actual temperature property. The way we handle such things in
> >> HL7 is like this:
> >>
> >> "Maximum temperature = 40 degree Celsius" is
> >>
> >> Observation (criterion)
> >> of quantity /core temperature/
> >> at time /any time/
> >> has value [15;40] degree Celsius
> >>
> >> "Actual temperature 25 degree Celsius" is
> >>
> >> Observation (actual)
> >> of quantity /core temperature/
> >> at time 2009-09-30T15:05
> >> has value [24.5;25.5] degree Celsius
> >>
> >> "Actual temperature 43 degree Celsius" is
> >>
> >> Observation (actual)
> >> of quantity /core temperatue/
> >> at time 2009-09-30T15:15
> >> has value [42.5;43.5] degree Celsius
> >>
> >> Comparison between a criterion and an actual quantity is done by
> >> comparing whether the actual quantity is included in the criterion.
> >> That way one can also define other criteria, such as
> >>
> >> "Alarm temperature at > 35 degree Celsius"
> >>
> >> Observation (criterion)
> >> of quantity /core temperature/
> >> at time /any time/
> >> has value [35;-) degree Celsius
> >>
> >> The difference between the 2 criteria is how they are related to
> >> other information. For example, operating temperature would be
> >> related to the operation act that the machine performs whereas
> >> alarm temperature would be related to the alarm action:
> >>
> >> Act "to operate properly"
> >> isPerformedBy Machine
> >> hasThroughCondition Observation (criterion) for "operating
> >> temperature
> >> range"
> >>
> >> Act "to raise alarm"
> >> isPerformedBy TemperatureMonitor
> >> hasSubject Machine
> >> hasTriggerCondition Observation (criterion) for "alarm temperature"
> >>
> >> so a lot of these notions of "indirect properties" is in my view
> >> best modeled by additional structures. But nevertheless one can
> >> always define a property as a primitive to stand for such a complex
> >> model. E.g.,
> >>
> >> "Maximum operating temperature of Machine X" :=
> >> the high boundary of
> >> the range value of
> >> the Observation (criterion)
> >> of quantity /core temperature/
> >> which is the throughCondition of
> >> the act of operating properly
> >> performed by
> >> the Machine X.
> >>
> >> If we avoid such "indirect properties" with such models, there are
> >> then fewer true "direct properties" left, such as /core temperature/.
> >> However, you still have multiple temperatures, such as
> >>
> >> - core temperature
> >> - surface temperature
> >> - measured by holding a thermometer close to the shell
> >> - measured by an attached thermometer (using heat transfer creme)
> >>
> >> and lo and behold, we can't really compare the core temperature and
> >> the surface temperature to find out if the machine is still
> >> operating.
> >> But we can compare the surface temperatures with core temperatures
> >> to find out that the surface temperatures are always closer to the
> >> ambient temperature than the core temperature.
> >>
> >> regards,
> >> -Gunther
> >>
> >> --
> >> Gunther Schadow, M.D., Ph.D.
> >> gschadow@xxxxxxxxxxxxxxx
> >> Associate Professor Indiana University School of
> >> Informatics
> >> Regenstrief Institute, Inc. Indiana University School of
> >> Medicine
> >> tel:1(317)423-5521 http://
> >> aurora.regenstrief.org
> >>
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