[Crm-sig] Issue 326 Resolving inconsistencies between E2, E4, E52 and E92

Robert Sanderson RSanderson at getty.edu
Tue Mar 12 16:27:46 EET 2019


Dear Martin, all,

I agree with your assessment into the four categories, and that the first three are met, and the last is more complicated.
I also agree with the formalism for E4. It moves some of the complexity around, and doesn’t introduce inconsistency for the temporal side of things for subclasses of E2.

However, I agree with George that this does not hold true for the other sub class of E92, being E18 Physical Thing.  With this subclass assertion, we can partition physical things based on time and then make assertions about those partitions using all of the sub-classes of E18.  For example, to say that the Nightwatch had a width of 17 feet between its production in 1642 and 1715 when it was trimmed to fit on a wall in the Amsterdam town hall, we could have an E22 for the painting throughout time, and use P10 to reference further E22s, each of which were clarified with P160 as to their temporal projection. These projections could then have different dimensions.

<Nightwatch> a E22_Man-Made_Object ;
    P10i_contains <Large_Nightwatch> , <Small_Nightwatch> .

<Large_Nightwatch> a E22_Man-Made_Object ;
    P160_has_temporal_projection [
         a E52_Time-Span ;
         P81a_begin_of_the_begin “1642-01-01”
         P82a_end_of_the_end “1715-12-31”  ] ;
     P43_has_dimension [
        P2_as_type <width-type> ;
        P90_has_value 17 ;
        P91_has_unit <feet-unit> ]

(and the same for Small_Nightwatch, starting 1715 with 14.3 feet as width)

This seems antithetical to the intent of the model (as I understand it) where activities (such as Modification in this case) are kept separate from the entities that they affect.

This particular pattern could be prevented by having E92 not be a sub class of E18, without affecting the P160 / P4 discussion.  However, I note some issues with making only this split:


·         It would still be valuable to have the STV of a physical thing, in order to calculate the intersection between the STV that a physical object projects with Periods (that are themselves STVs). So it would be valuable to introduce a relationship between E18 and E92, introducing pattern inconsistency.

·         While Period and Event seem to share the identity conditions with STV, Activity and below start to seem less identical. I worry that I become the space-time volume of the sum of my activities… and then I am a STV again, even though we removed it from E18 for just this reason.

·         The same issue for P160 / P4 would apply for P161 / P53 – the spatial projection of the object is its former or current location, as they have the same identity currently.

So overall, I think my position is that for consistency of the model, E92 should not be a subclass of either E4 or E18, but instead related via a property.

Hope that helps!

Rob


From: Crm-sig <crm-sig-bounces at ics.forth.gr> on behalf of Martin Doerr <martin at ics.forth.gr>
Date: Tuesday, March 12, 2019 at 6:09 AM
To: "steads at paveprime.com" <steads at paveprime.com>, 'George Bruseker' <bruseker at ics.forth.gr>
Cc: 'crm-sig' <Crm-sig at ics.forth.gr>
Subject: Re: [Crm-sig] Issue 326 Resolving inconsistencies between E2, E4, E52 and E92

Dear Steve, George,

Your arguments well taken, I may remind you that the argument was not only a 1:1 relation.

It contained 4 elements:

a) a 1:1 relation
b) a common identity condition: The identity of the STV depends on the identity of the phenomenon
c) There existence conditions are identical: the one exists where and as long as the other
d) Properties do not interfere.



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