[Crm-sig] (no subject)

martin martin at ics.forth.gr
Fri Jul 3 14:29:25 EEST 2009


Dear Bernhard,

Their is no "clear cut" beginning for any real world physical process, nor can two independent observers
come up with exactly the same beginning for a physical process. In case a beginning is based solely on human agreement,
as the validity of a contract, it is "clear cut", and only then, and then simply inner and outer bounds are identical.
The outer an inner bounds are human estimations of real boundaries, and therefore "exact" in the sense of being
approximations, outcome of observations but not subject to observation. Therefore, it makes no sense to deal with
them as fuzzy (asss - asse).

See also: http://www.ics.forth.gr/isl/publications/paperlink/caa2004_supporting_chronological_reasoning.pdf

In another paper, we describe this possibly endless recursion of begin of begin of begin etc., and come to the
conclusion, that there are (must be) periods which do not begin or end by a distinct physical event, and that any
event that may mark the begin of a period may in general not begin with another marking event.

http://www.ics.forth.gr/isl/publications/paperlink/CIDOCpaper1_Doerr.pdf

Any fixed granularity discrete time model, such as going down to days, actually describes time in elementary intervals,
and not any "clear cut" point in time. This is why we recommend to have a time primitive which is dealt with as interval.
What does xsd:dateTime denote, the begin or the end of the referred second?

Best,

Martin

Bernhard Schiemann wrote:
> Dear all, Christian-Emil,
> 
> 
> Thank you for your feedback! Let me start with a comment on the versions
> of our implementation: There is one version without the p79a and p80a
> properties and one version with these properties (marked TQ)
> available on
> http://www8.informatik.uni-erlangen.de/IMMD8/Services/cidoc-crm/versions.html
> 
> 
>> I question the need for the
>> additional properties P79A and P80A. They represents a fixation and
>> oversimplification of the start and ending points of the time spans >>
>> which is not justified when using the CIDOC CRM as a model for
>> reasoning about event chronology. Below I have pasted the
>> introduction of presentation Jon
>> Holmen and I gave at CAA2009 Williamsburg, USA.
> 
> Could you please send us the full CAA2009 paper?
> 
> 
>> On the other side, in scientific work a time-span represents an
>> abstract approximation to the temporal extent of an event. The exact
>> start and end points are usually not known. In the CIDOC-CRM this
>> approximation to the temporal extension of events is modeled as two
>> intervals on the timeline, one for the outer bounds (P81 at sometime
>> within) and one for the inner bounds (P82 ongoing throughout), see
>> fig. attached. In an ideal situation with absolute accuracy, these two
>> intervals should be identical. In most actual research they are not.
>> In many cases there is only information about an outer interval (at
>> sometime within), that is, by some terminus post quem (TPQ) and
>> terminus ante quem (TAQ) for the event.
> How do you express (an idealized) "clear cut" beginning?  I ask because
> there
> is no property addressing this question which connects E52 to E61 (where
> E61 is the candidate for a "clear cut" beginning).
> The same holds true for Ass,Ase,etc. because for the same reason the
> only way
> to express Ass etc. would be to assume another time span from Asss to
> Asse and so on.
> 
> For example, to calculate relations between E2`s ("time operators P114
> is equal in time to, P115 finishes, P116 starts, P117 occurs uring, P118
> overlaps in time with, P119 meets in time with, P120 occurs before") one
> needs concrete values, such as "xsd:dateTime" in order to make calculations.
> 
> 
> 
> Kind regards
> Bernhard
> 
> 
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  Dr. Martin Doerr              |  Vox:+30(2810)391625        |
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