ABSTRACT
Recent work in planning has rejected the assumption of a closed, stable world, and the associated paradigm of exhaustive preplanning, which encounters serious problems trying to plan in a world where that assumption does not hold. Several alternative strategies have been proposed, responding to these new problems in a variety of ways. We review this spectrum, finding the various approaches in part incompatible but not bereft of some common themes and complementary strengths. We suggest factors in the application domain which should influence the appropriate mix, and describe the TRUCKER project to illustrate some of the problems and benefits in implementing such a mix.
