[Crm-sig] Issue 511

Martin Doerr martin at ics.forth.gr
Tue Mar 2 23:25:37 EET 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.

Best,

Martin

-- 
------------------------------------
  Dr. Martin Doerr
               
  Honorary Head of the
  Center for Cultural Informatics
  
  Information Systems Laboratory
  Institute of Computer Science
  Foundation for Research and Technology - Hellas (FORTH)
                   
  N.Plastira 100, Vassilika Vouton,
  GR70013 Heraklion,Crete,Greece
  
  Vox:+30(2810)391625
  Email: martin at ics.forth.gr
  Web-site: http://www.ics.forth.gr/isl

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