[Crm-sig] Extended CRM Graph of E52 Time-Span

Bernhard Schiemann Bernhard.Schiemann at informatik.uni-erlangen.de
Fri Jul 31 17:58:24 EEST 2009

Dear all,

the reason why we introduced P79a and P80a was that we cannot see from
the latest release of the CRM text how the following problem can be

(For illustration see the attached edited version of Cristian-Emil's

There is an E52 Time-Span named A which has an "interval for start
point(!)" called A_s and an "interval for end point" called A_e.
Hence, A is a fuzzy time-span with a vague start and and a vague end.

The starting interval A_s has borders A_s_s (start) and A_s_e (end)
--- and the same holds by analogy for A_e.  The CRM document relates
A_s_s and A_e_e by P82 at some time within and A_s_e and A_e_s by P81
ongoing throughout.

NOW: If we want to express the relation between A_s, which is an E52
Time-Span, and its start A_s_s, what ist the appropriate property to be
used?  This depends on what A_s_s is:

- If its also interpreted as an E52 Time-Span, there is no reason not
  to repeat this step which will result in an infinite recursion.
  Furthermore, it does not really make sense in the framework we are
  dealing with: We want to talk about time intervals with vague
  (fuzzy) borders; so what would it mean if we make the borders of the
  start and end intervals fuzzy in turn, i.e. making vague the start
  of the start of the start... ?

- Another interpretation would be to regard A_s_s as an E61
  Time-Primitive which is given precisely (with an a priori assumed
  granularity of time determination depending on the respective
  application).  A footnote aside: We may shift A_s_s etc. forth and
  back on the time line until we have sufficient certainty with
  respect to P82 or P81, respectively.

If we decide for the second interpretation, our suggestion for the
properties to relate A_s and A_s_s was P79a and for A_s and A_s_e it
was P80a.  Otherwise, the only eligible CRM relations we can see to
relate E52's to E61's are (the already employed) P81 and P82.

In contrast to Martin's suggestion (July 2) A_s_s and A_s_e are
preserved as E61 Time-Primitives (which still have an interval
property in terms of the choosen granularity; see above).

So, of course, P79a and P80a where not at all conceived as a kind of
replacement for A_s_s and A_s_e.  But if we want to "calculate" with
time intervals, as a scope note in the CRM document, referring to
Allens constraint system, says, it must be possible to determine
values for A_s_s and A_s_e of some data type, e.g. xsd:dateTime.

Probably there are alternative solutions --- therefore we put the
issue on the list to stimulate a constructive discussion.  So far, we
cannot see any; of course we acknowledge the detailed explanation
referring to start and end intervals which set the frame for possible
solutions but does not yet provide one.  Maybe our P79a / P80a
suggestion is "oversimplified", but what would then be alternative
more complex, but appropriate solution?

Dear Martin, it seems that you have not noticed that "clear cut" was a
quotation (therefore the quotation marks) from Christian-Emil's
original mail where he quotes from a paper he published recently. So
you will have to discuss the proper use of terms with him.

As for the remark in your mail of July 2 on the the use of abstract
datatypes in ontologies, there is a lot of literature which says the
opposite. In particular you may have missed the recent recommendations
of the W3C for OWL2, the Web ONTOLOGY Language, which offers extended
means for the definition of abstract datatypes (sometimes also called
"concrete domains").  One of the reasons was to avoid reference to
xsd:... datatypes which, although permitted, some people in the OWL
group found troublesome.  To provide means for the definition of
expressive abstract datatypes within the language is quite  obvious
--- and has been an issue on the side of applied logics for more than 15
years ---, because you need them in order to get some real inference
tasks with real data to be done.

On behalf of the authors from Erlangen, Best regards,

Bernhard Schiemann, Dipl. Ing.
Artificial Intelligence Division
Department of Computer Science
University of Erlangen-Nuremberg
Haberstr. 2, D-91058 Erlangen, Germany

Tel.:  +49-9131-85-28984
Fax :  +49-9131-85-28986
Email: schiemann at informatik.uni-erlangen.de
To verify my keys, please use gpg keyserver:
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