[Crm-sig] Activity Partitioning (was Actors acting for other Actors)

Robert Sanderson RSanderson at getty.edu
Fri Apr 17 18:53:19 EEST 2020


Dear all,

This discussion (and the partitioning aspect of it) reminds me of a niggling concern that came up in the Linked Art work about scope note of P9 when applied to activities.

In particular, P9 only talks about the part being a subset of the phenomena of the whole:

This property associates an instance of E4 Period with another instance of E4 Period that is defined by a subset of the phenomena that define the former.

To what extent can we infer knowledge through the P9 link, if any? For example, if there is the activity of writing a book which was carried out by a Person, I don’t think it is legitimate to conclude that the part of writing a chapter was also carried out by that same person.

If X consists_of Y, and X carried_out_by Z, then it is not necessarily the case that Y carried_out_by Z, due to the open world assumption.  It could be that X was also carried out by A, B and C, but that was just not stated. Therefore Y could have been carried out by anyone.   And the same argument for all other relationships and properties.

Do we even know that the part is within the same temporal period as the whole? I don’t think so, given that P4 allows alternative opinions about it expressed by assigning multiple Time-Spans to the same E2 Temporal Entity, rather than creating a new E2 and having a 1:1 relationship with TimeSpan. So the part could occur temporally within an undocumented alternative opinion about the timespan. We would thus instead need to also assert P117 occurs during … which is not a sub-property of P9 or vice versa.

P9 is a sub property of P10, which has a domain and range of Spacetime Volume… so this will need to change with the change of STVs no longer being a parent class of Period? At which point we could ensure that P9 implies both P117 and some spatial equivalent?

Conversely, it seems that P9i forms part of IS a strong assertion. If we assert that the part was carried out by A, then the whole MUST have been carried out by at least A, because the carrying-out of the part is a subset of the carrying-out of the whole.  Thus, we should prefer to use P9i, as it enables stronger inferences and understanding.  But … then if we assert that an Activity is part of a Period (rather than merely occurs during it), then the carrying-out-ness is a part of the phenomena of the Period … which cannot be carried out as it’s not an activity.

Result:    :head-exploding-emoji:

For now we have chosen to ignore these issues in linked art for the sake of sanity and convenience. However if there is guidance or improvements that can be made, we would be happy to contribute to those discussions! 😊

Rob

The original issue: https://github.com/linked-art/linked.art/issues/316








--
Dr. Robert Sanderson,  Semantic Architect  |  Getty Digital  |  getty.edu<http://getty.edu/>
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