10.1.2 Forward Projections and Backprojections

A *forward projection* is a useful concept for characterizing the
behavior of plans during execution. Before uncertainties were
considered, a plan was executed exactly as expected. When a sequence
of actions was applied to an initial state, the resulting sequence of
states could be computed using the state transition equation. Now
that the state transitions are unpredictable, we would like to imagine
what states are possible several stages into the future. In the case
of nondeterministic uncertainty, this involves computing a set of
possible future states, given a current state and plan. In the
probabilistic case, a probability distribution over states is computed
instead.

Steven M LaValle 2012-04-20