Cervesato et al Article Accepted
The article by Iliano Cervesato, Massimo Franceschet, and Angelo
Montanari has now been accepted after reviewing and refereeing.
Congratulations to the authors! We remember that the open review
debate was quite thorough, with detailed questions by Paolo
Liberatore, Peter Jonsson, and Rob Miller, and extensive answers
by the authors. This is what most of all contributes to the
quality processes of our journal - and to the public recognition
and confidence in it.
In the present issue we also have a question by Chitta Baral to
Hector Geffner, concerning some of his remarks in the discussion
with David Poole about David's submitted article.
Also, Erik Sandewall has a few questions to Johan van Benthem,
for his contribution to the discussion on ontologies of time.
This will be the last issue of the ENRAC for 1998. We have had a very
interesting year, and many thanks to all who contributed articles
and discussion items. The next issue will appear some time after
January 10.
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Discussion about received articles
Additional debate contributions have been received for the following
article(s). Please click the title of the article to link to the
interaction page, containing both new and old contributions to
the discussion.
David Poole Decision Theory, the Situation Calculus and Conditional Plans Review protocol: [in this pane]; with links: [frame] [noframe]
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Ontologies for time
Dear Johan,
Thank you for your very insightful note for the discussion about
ontologies of time. Here are a few questions on this topic.
- You point at the fact that some predicates are such that they
intrinsically only apply to intervals. True, but some of the proposed
instances of the DI problem are formulated for predicates that do
apply to points without problems, for example, Galton's example
with the red an the green lamp in the traffic light. (One may
argue that lightbulbs 'really' have intermediate states where they
glow without shining, but whatever state they have they do have it
at timepoints). Ought we not deal with those problems first?
- a) With respect to the "good luck" re using Real Time: after all,
zillions of engineers and scientists in physics and engineering
sciences use Real Time and are happily unaware of any
complications in that respect. If they can do so, why can't we?
and more precisely, what is the Bad that can happen if we
follow their suit?
b) Continuing (a): if we decide that Real Time is Good Enough
for us, does the Dividing Instant problem then apply, or is it
irrelevant?
- Re the axiomatic vs intended models approach: I must admit I don't
feel at home with either, the way I read your distinction in
section 5. The axiomatic approach requires one to specify axioms
for the chosen temporal domain, for example, for the reals in case
these are chosen as timepoints? The intended structure approach, on the
other hand, seems to require or at least suggest that the structure
is constructed from timepoints, intervals, and so on, and thereby
that it implements a solution to the DI.
The approach I suggested in the discussion, and for which I asked
in vain for an explanation of why and where it would get into
trouble, was to take the time domain as given (real numbers), to
axiomatize the statements about the chronicle i.e. the events
but not the time domain itself, and to obtain the models (plural,
potentially) for those axioms. Then the undefinedness of some
predicates at the dividing instants would be represented by having
several models, but in each model each predicate would be either of
true or false. I guess you could say that in this case the intended
structure is a set of models, but did you intend that reading?
Best regards,
Erik
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