Re: Planning under Description Logic ?--an obstacle towards WSAC

Quoting Drew McDermott <>:

> > [Jeff (Dalton?)]
> > However, HTN planners don't have to generate sequential plans.
> > With O-Plan, for example, the final plan is still only a partial
> > order.
> For most partial-order planners, if the end result is not totally
> ordered, that means that any total order consistent with the final
> partial order will work.  So the semantics is still that of
> interleaved atomic actions, not "true" concurrency.  I realize that
> the "O" in "O-Plan" means "open," so O-Plan probably doesn't insist on
> this interpretation (and probably doesn't support any particular
> interpretation).

Perhaps Austin has a different understanding of this, but I don't
think that an openness to different interpretations is implied by
the "open" in O-Plan.  O-Plan could be set up with different
knowledge-sources and different constraint managers that
implemented a understanding of plans, but normally that would be
for different constraint types.  We don't think of a temporal
"before" constraint, for example, of having a semantics that

However, I don't think true concurrency is disallowed by the
semantics we usually use.  We have ordering constraints that
say, for example, that action A must complete before action B
can begin; but if there are no such constraints between
two actions, I don't think anything says they can't
happen concurrently.

-- Jeff

Received on Tuesday, 7 December 2004 21:26:51 UTC