Hi! (An issue that arose at public-esw-t...@w3.org under subject Re: TGN place types (broader/narrower spanning ConceptSchemes) and was discussed to some extent between me and Richard Light)
There are many "dual" Events in CRM that indicate the Start/End of something: - Beginning/End of Existence - Birth/Death of a person - Identifier Assignment with props assigned/deassigned - Acquisition with props transferred from/to - Transfer of Custody with props from/to - Production/Destruction (not completely dual) - Part Addition/Removal - Formation/Dissolution of a group - agent Joining/Leaving a group There are also events that indicate Start, without a corresponding End event: - Creation (End is not appropriate, since conceptual things are forever) - Type Assignment (IMHO should also have "type deassigned", just like Identifier Assignment) HOWEVER, there is no standard way to state the "Period of use/existence/activity of something", such as: - period of use of an Identifier (Appellation, Title), Type - life of a Person - floruit of a Person - period of group membership or profession of a Person (e.g. reign) One would have to model them as Event/Activity in which the concerned entity participated, with some P2_has_type. We also need to relate the start/end events to the period of existence. P116_starts and P115_finishes almost fit the bill, though they bind only one of the endpoints. E.g. P115: "allows the ending point for a E2 Temporal Entity to be situated by reference to the ending point of another temporal entity of longer duration". P115 makes no relation between the starting points. But Death is *the* end of Life, so *both* points of Death must be strongly related to the ending point of Life. - We could introduce sub-properties: P216 really starts (really started by): "an E2 Temporal Entity (e.g. Birth) is considered to be "momentary", and is the start of a longer E2 Temporal Entity (e.g. Life)" P215 really finishes (really finished by): "an E2 Temporal Entity (e.g. Death) is considered to be "momentary", and is the finish (end) of a longer E2 Temporal Entity (e.g. Life)" - These should be subproperties not only of starts/finishes, but also of forms_part_of : P216_really_starts rdfs:subPropertyOf P116_starts, P9i_forms_part_of. P215_really_finishes rdfs:subPropertyOf P115_finishes, crm:P9i_forms_part_of. (This is optional, we could just use P116 and P115) Finally, we need some rules to relate the 4 time-points (P82a, P81a, P81b, P82b) of the Start/End events to those of the Existence period. I'm not sure what the rules should be... One approach could be that: - Start/End are considered "momentary" events, thus have only 2 points (P81a=P82a, P82b=P81b) - these points correlate to Existence as follows: Start.P82a=Existence.P82a, Start.P82b=Existence.P81a, End.P82a=Existence.P81b, End.P82b=Existence.P82b. Maybe this is a bit naïve, since: - "momentary" is a relative term. Birth could be described as a minute event, usually is described as an the "expected" inequalities P82a<=P81a<=P81b<=P82b do not always hold, see Deducing event chronology in a cultural heritage documentation system (Holmen & Ore, CAA 2009) Modeling such Periods of Existence is significantly more economical than modeling with Start/End events. So I think this is a new important shortcut pattern: one event (e.g. Life) being the shortcut expression of two events (Birth/Death). I expect the classical objection will be raised, that Life is not used often in cataloging practice. But if there's enough interest to have explicit classes for Birth/Death, how can there be not enough interest to have specific class for Life? In the attached Turtle file I've defined a couple of extension classes (Life and Membership) and given some examples. Note that Joining/Leaving are longcuts of Membership, which itself is a longcut of P107_has_current_or_former_member. So it's interesting that we've discovered an expression at intermediate level of detail between super-detailed (Joining/Leaving) and undetailed (P107) I give an example of a king whose reign finishes with his life (descension coincides with Death). It would be interesting to try to model Picasso's creative periods with this machinery, e.g. see http://en.wikipedia.org/wiki/Picasso http://en.wikipedia.org/wiki/Picasso%27s_Blue_Period Cheers! Vladimir
CRM-start-finish-period.ttl
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