Dear Simon,
I have the impression that you take the density of time, to which CRM
commits, for the decomposition of phenomena happening in time, which is E2,
the nature of E2 is not the nature of time however.
Further, you seem to talk about the question if there are minimal
elements, that cannot be subdivided further. For time, the CRM does not
assume that, as you argue. Currently, the CRM assumes only for Actor
minimal elements of decomposition.
The first question is rather, if there are phenomena in time that reveal
a structure with distinct recognizable identities that have a part-whole
relationship, such as "Early Minoan" and "Middle Minoan". They are
identified by observable characteristics, not by subdivision on the
time-line.
The second question is, if these part-whole relationships can be mixed
between subcategories: Can a natural part of a Condition State be an
Event, or can a E4 Period ever have a part which is a Condition State?
If not, then a common property would produce "non-intended models" as
Nicola Guarino describes it. This cannot always be avoided, but we try
to minimalize this effect.
Finally, CRM properties are optional, so there is no commitment given by
the definition of a part-of property, that all instances of that class
must have parts. Indeed, for material objects, we may end up with
nuclear particles as end points, but those are out of scope, but long
before, the notion of a Physical Object would loose its meaning.
If there is a characteristic class in scope which forms the minimal
elements, then we would model the decomposition down to this class, as
in the case of Actor and Person.
The question if the labels of these part-of relations should be
different is interesting. So far we have prefered that they have all the
same name, because that renders the meaning clearly, but different
P-number, which renders the constraint. To include the class name in the
label may be another method to render the constraint, but it produces
long names difficult for translation, and is counterintuitive when used
with subclasses, such as an Event consisting of several Periods, or a
Period consisting of Events, which is intended.
Comments?
Martin
On 13/5/2014 12:51 ??, Simon Spero wrote:
On Mon, May 12, 2014 at 3:53 PM, Stephen Stead <[email protected]
<mailto:[email protected]>> wrote:
The question is not could we generalise the property to E2 but are
there potential instances of E2 that are not E3's or E4's that
potentially do not have decomposition. I do not know and
additionally I am not sure I want to
spend a lot of time making sure that by their very nature all E2's
are decomposable!!
This actually a rather significant ontological decision.
If there are temporal entities that cannot be so divided then the
underlying temporal ontology is /discrete. /
If every temporal entity can always be so decomposed, then the
underlying temporal ontology is /dense/.
CRM is committed to a dense ontology (because of the approximate model
of time points, and the rejection of any momentary events*) , so it
would seem all E2 must be decomposable.
It is of course, not the case that the type of every part is the same
as the type of the whole; conversely, there may be certain
granularities where each part /is/ of the same type - e.g. the
granularity of a step, each part of a walk is also a walk.
Simon
* e.g. "the upward velocity of the ball I just tossed becoming zero"
is not considered to be momentary, in spite of calculus, because the
precise beginning and end points are cannot be defined as equal, just
not distinguishable.
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