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Re: [ontolog-forum] problem understanding subClass used

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Simon Spero <ses@xxxxxxx>
Date: Fri, 17 Dec 2010 11:09:31 -0500
Message-id: <AANLkTik-hrQaiWX_2ThvTJwGek4x+WqRA73z2M9Ce6wM@xxxxxxxxxxxxxx>
I would guess that the ontology in question is the CIDOC Common Reference Model (CRM), which was standardised as ISO 21227:2006.  The concepts  of E5 Event and E4 Period in the CRM are a little confusing.

An E4 Period is a set of  "coherent phenomena or cultural manifestations" that are "bounded in time", but it is the phenomena/manifestations that define the E4 Period, not the time interval in which they occur.  There is a separate class, E52 Time-Span , which represents time ranges, with start and end points.  The things that are members of an E4 Period must have some unifying conceptual theme. John Doe's  eating of lunch on July 27th 1942 (E5)  would not be an element of The Battle of Stalingrad (E7).


he Birth of Cleopatra (E67),

 considered from the point of view of a 21st century museologist, can be thought of as an E5 Event and treated as if it happened instantaneously.   >From the point of view of Cleopatra's mother, it probably seemed to take a lot longer, and involve much more swearing.  

Note that the happening of a birth is a beginning of existence

E67 Birth  ⊑ E63 Beginning of Existence ⊑ E5 Event   Temporal Entity  E1 CRM Entity

but Cleopatra's mother giving birth to Cleopatra would be an instance of an E7 Activity

E7 Activity ⊑ E5 Event   Temporal Entity  E1 CRM Entity

The creation of a Conceptual Work (E65 Creation) is defined as both an E7 Activity and an E63 Beginning of Existence

Confusingly (to me, anyway), The Battle of Stalingrad (E7)  is an E7 Activity. 


On Wed, Dec 15, 2010 at 11:11 AM, Paul Hermans <paul@xxxxxxxxx> wrote:
The ontology I'm studying now is about Cultural Heritage.

In this ontology there is a class "Event"
"the Yalta Conference", "the birth of Cleopatra", "my car accident of last friday", "the big bang"

A second class is "Period" with definition 
"European Bronze Age", "Italian Renaissance".

Now what puzzles me is that Event is defined as a subClass of Period.
So "the Yalta Conference", "the birth of Cleopatra", "my car accident of last friday", "the big bang" all become instances of Period.

The rationale for doing this according to the ontology:
"The distinction between an Event and a Period is partly a question of the scale of observation. Viewed at a coarse level of detail, an Event is an "instantaneous" change of state. At a fine level, the Event can be analyzed into its component phenomena within a space and time frame, and as such can be seen as a Period."

I still find it difficult to consider something that instantaneous changes state is automatically and at the same time something stable and coherent. 

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