Re: Revised daml-time.pddl

From: Drew McDermott (
Date: 10/31/02

  • Next message: pat hayes: "Re: Revised daml-time.pddl"
       >1) Yoav Shoham worked out an exhaustive taxonomy of eventuality types
       >    as part of his Ph.D. work.  Different types behave differently with
       >    regard to whether holding over an interval implies holding at each
       >    instant of the interval, and other such distinctions.  I'm not sure
       >    where to find the taxonomy, but we could ask Yoav.
       Obviously I havn't been tracking this stuff closely enough.
       I would be very unhappy if daml-time requires us to swallow an 
       ontology of 'eventualities'. Seems to me that there is no need to 
       ever introduce eventualities in a well-designed ontology; they are 
       just the sentences that are true at a time, and if one writes things 
       properly then they can stay being sentences.
    In spite of intense philosophical meditation, I have been unable to
    disambiguate your proposal.  Can you clarify?  For instance, does a
    sentence's being true "at a time" cover the case where the time is an
    interval?  Do you intend to reify sentences or to make the time be an
    extra argument to temporal predicates?
    In any case, daml-time can remain independent of any ontology of
    eventualities, if some people decide they want one, or more than one.
                                                 -- Drew

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