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Drew,

Good point about the importance of noncontiguous eventualities.

What time-span-of would mean in a branching futures model of time is
an interesting question, which I hope would not lead to excessive
complication.  

By the way, everyone, I had daml-time@bbn.com in my original mailing
where I should have had daml-time@daml.org.  The present mailing list
is correct.

-- Jerry


Drew McDermott wrote:
> 
> Jerry -- The temporal ontology is nicely done.  I am a bit confused
> over "eventualities," however:
> 
>    2.4.  Linking Time and Events:
> 
>    ...
>    The term "eventuality" will be used to cover events, states,
>    processes, propositions, states of affairs, and anything else that can
>    be located with respect to time.  The possible natures of
>    eventualities would be spelled out in the event ontologies.
> 
>    ...
>    The predicate time-span-of relates eventualities to instants or
>    intervals.  For contiguous states and processes, it tells the entire
>    instant or interval for which the state or process obtains or takes
>    place.
> 
>            time-span-of(T,e) --> temporal-entity(T) & eventuality(e)
>            time-span-of(T,e) & interval(T) --> during(e,T)
>            time-span-of(t,e) & instant(t) --> at-time(e,t)
>            time-span-of(T,e) & interval(T) & ~inside(t1,T)
>                    & ~start-of(t1,T) & ~end-of(t1,T)
>                --> ~at-time(e,t1)
>            time-span-of(t,e) & instant(t) & t1 =/= t --> ~at-time(e,t1)
> 
>    time-span-of is a predicate rather than a function because until the
>    time ontology is extended to aggregates of temporal entities, the
>    function would not be defined for noncontiguous eventualities.
> 
> You should clarify that most eventualities *are* noncontiguous.  I'm
> thinking of eventualities such as weather(Afghanistan, cloudy).  The
> only contiguous ones are particularly historical events such as
> GulfWar.  (Even those become noncontiguous if you allow some time
> points to be in hypothetical universes, which may sound esoteric, but
> would be useful in talking about alternative operational plans.)
> 
>                                              -- Drew

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