Issue 511: Measurements and Dimensions

ID: 
511
Starting Date: 
2020-09-09
Working Group: 
3
Status: 
Open
Background: 

Posted by Robert Sanderson on 9/9/2020

Dear all,

I believe that there is an inconsistency in the model for measurements and dimensions.

E54 Dimensions are associated directly with E70 Things using P43 has dimension.  So not every class can have dimensions, only those that are descendents of E70.

However E16 Measurement's property P39 measured has a range of E1 CRM Entity, meaning that while (for example) an E53 Place cannot have a dimension, it can be measured to have a dimension. This seems inconsistent that an entity that cannot have dimensions can still be measured.

I propose that the range of P39 measured be changed to E70 Thing to resolve this inconsistency.

I would also be okay with the other direction by changing the domain of P43 has dimension to be E1 CRM Entity, however that seems like a much more significant change, and would result in quite strange side effects such as Dimensions having Dimensions.

Posted by Thanasis on 9/9/2020

Good point, but it seems to me that being able to measure a Place is pretty important. Otherwise we have to measure through the physical object/site reference or the declarative space as part of a conceptual thing.
 

Current Proposal: 

Posted by Robert on 9/9/2020

Thanks Thanasis.  Yes, there's various dimensions that are associated with non-Things, and I agree that Place is particularly easy to justify.

Place:  Area. The county of Los Angeles has a dimension of 4751 square miles. If the place is approximate, then the radius of a centroid would be an obvious dimension to record, or height/width for bounding box defined Places.

Time-Span:  Duration is already a property of a Time-Span that refers to a dimension (P191). This could then be a subproperty of P43, or deprecated in favor of a classification on the Dimension.

Temporal Entity and Spacetime Volume are a bit strange in relation to Time-Span. Does the Period have the duration or the Time-Span, or both? What if they're different

Conversely Dimensions seem like they should not have Dimensions.

Posted by Athina on 9/9/2020

As I remember, this problem was discussed in issues 229 and 307, which are declared closed. However, I am wondering, if it is related to the issue 293?

Posted by Robert on 9/9/2020

Oh, I'm sorry for duplicating your original issue 229 Athina! Great minds think alike, perhaps?

It seems like 229 was closed in favor of discussing it as part of 307, but that discussion didn't happen. 293 does seem like a good venue, but ultimately there is an inconsistency right now (as you recognized long ago!) that should not persist in version 7.0 regardless of whether ObservableEntity / Observation are moved into CRM Core or not.

Posted by Martin on 09/09/2020

On 9/9/2020 7:47 PM, Robert Sanderson wrote:

 

Oh, I'm sorry for duplicating your original issue 229 Athina! Great minds think alike, perhaps?

 

It seems like 229 was closed in favor of discussing it as part of 307, but that discussion didn't happen. 293 does seem like a good venue, but ultimately there is an inconsistency right now (as you recognized long ago!) that should not persist in version 7.0 regardless of whether ObservableEntity / Observation are moved into CRM Core or not.

I agree.

Posted by Martin on 09/09/2020

Indeed durations can be measured as distances between two events. Einstein regarded that length measurements are two simultaneous events matching both endpoints of a yardstick with something. This is the basis of the Theory of Relativity.

Basically we have to do with signals.

To be discussed!

Posted by Martin on 2/3/2021

Dear All,

Let me take up this issue, after new considerations:

Background:

Posted by Robert Sanderson on 9/9/2020

Dear all,

I believe that there is an inconsistency in the model for measurements and dimensions.

E54 Dimensions are associated directly with E70 Things using P43 has dimension.  So not every class can have dimensions, only those that are descendents of E70.

However E16 Measurement's property P39 measured has a range of E1 CRM Entity, meaning that while (for example) an E53 Place cannot have a dimension, it can be measured to have a dimension. This seems inconsistent that an entity that cannot have dimensions can still be measured.

I propose that the range of P39 measured be changed to E70 Thing to resolve this inconsistency.

I would also be okay with the other direction by changing the domain of P43 has dimension to be E1 CRM Entity, however that seems like a much more significant change, and would result in quite strange side effects such as Dimensions having Dimensions.

……

Posted by Robert on 9/9/2020

Thanks Thanasis.  Yes, there's various dimensions that are associated with non-Things, and I agree that Place is particularly easy to justify.

Place:  Area. The county of Los Angeles has a dimension of 4751 square miles. If the place is approximate, then the radius of a centroid would be an obvious dimension to record, or height/width for bounding box defined Places.

Time-Span:  Duration is already a property of a Time-Span that refers to a dimension (P191). This could then be a subproperty of P43, or deprecated in favor of a classification on the Dimension.

Temporal Entity and Spacetime Volume are a bit strange in relation to Time-Span. Does the Period have the duration or the Time-Span, or both? What if they're different

Conversely Dimensions seem like they should not have Dimensions.

 .......................

We have to distinguish measurement from dimension. In order to measure something in a narrower sense, I need an observation of something material. Dimensions can also be result of computation, evaluation and estimation (forms of Attribute Assignment).

If we look at measuring in the narrower sense, we can count the characters of a text on paper, but not the abstract text. The logical representation of a text can be evaluated for its dimensions.

We cannot measure a place, but features at a place. See also Issue 388. But clearly, we can measure duration and extent of processes, and comparing a clock, which provides a duration from the last sync event, with some other transient situation or microevent, in order to calculate absolute time.

So, we may assign the ability to be observed to E18 physical things and E4 Period, or more narrowly to E5 Event.  The ability to be observed appears to need some common ontological nature, a certain materiality interacting with measurable signals. Even the lightning creates a plasma hose lasting some milliseconds. That would need a new class “Observable Entity” as range.

Otherwise, we may regard measuring physical things and measuring processes as independent. Then, we would need another measurement class, such as “static measurement” versus “dynamic measurement”.

Dimensions of other things, such as places in the abstract geometric sense of the CRM, need not be based on a common property. The place can only have diameters and areas as dimentions, and may be some more exotic ones. The dimension in the phenomenal timespan is of course that of the respective period etc. So, my argument being that E53 Place, E52 Time-Span have their own properties with range Dimension, without being regarded as observable (rather results of observation).

I’d propose the following:

Reduce in CRMbase Mesaurement , P40 observed dimension, to E18 Physical Thing. Add 3 different properties “has dimension” in CRMBase to E70 Thing, E53 Place, E4 Period (or E2 Temp Entity).

Extent CRMSci by E18, E4 IsA Observable Entity, and extend Mesaurement P40 observed dimension,  from E18 to Observable Entity.

Alternatively, introduce “Dynamic Measurement”  in CRMSci.

Posted by Robert Sanderson on 2/3/2021

Martin wrote in particular:

  Reduce in CRMbase Mesaurement , P40 observed dimension, to E18 Physical Thing. Add 3 different properties “has dimension” in CRMBase to E70 Thing, E53 Place, E4 Period (or E2 Temp Entity).

I agree with your argumentation, and believe that the changes in CRM Base would be:

P39 measured:

  Range changes from E1 CRM Entity to E18 Physical Thing

PXX1_has_dimension 

  Domain: E53 Place

  Range: E54 Dimension

PXX2_has_dimension

  Domain: E4 Period

  Range: E54 Dimension 

to be cognate with P43 has dimension for E70s.

The question would remain about the measuring of Non-physical Things, such as the number of symbols in a E90 symbolic object... but I don't have that use case, so am happy to leave the discussion to someone that does :)

Posted by Martin on 03/03/2021

Dear Robert,

Yes, exactly.

My argument about measuring non-physical things is that it does not constitute an observation process, but an abstraction from observable things. We can always use Attribute Assignment for such evaluations.

So, we can assign the word count to a text, without using E16 Measurement.
 

Posted by Daria Hookk on 03/03/2021

It's always comparison with something, we fix difference.

Posted by Robert Sanderson on 03/03/2021

On Wed, Mar 3, 2021 at 5:54 AM Martin Doerr <martin@ics.forth.gr> wrote:

My argument about measuring non-physical things is that it does not constitute an observation process, but an abstraction from observable things. We can always use Attribute Assignment for such evaluations. So, we can assign the word count to a text, without using E16 Measurement.

Understood, and agreed. The scope note for E16 is clear that is for measuring "physical properties ... by ... direct observation of particular states". 

A word count would be an Attribute Assignment of the Dimension to the Linguistic Object, potentially using a particular specific object as a witness for the symbols. Of course, I can count symbols in my head, but then I am not observing the symbols physically, and therefore it is not a Measurement.

If I am not able to be at the SIG session where this is discussed, please count this as my vote in favor of the resolution of the issue.