ON THE IMPLEMENTATION AND EVALUATION OF ABTWEAK

In this paper, we describe the implementation and evaluation of the AB TWEAK planning system, a test bed for studying and teaching concepts i n partial-order planning, abstraction, and search control. We stare by extending the hierarchical, precondition-elimination abstraction of A BSTRIPS to partial-order-based, least-commitment planners such as TWEA K. The resulting system, ABTWEAK, illustrates the advantages of using abstraction to improve the efficiency of search. We show that by prote cting a subset of abstract conditions achieved so far, and by imposing a bias on search toward deeper levels in a hierarchy, planning effici ency can be greatly improved. Finally, we relate ABTWEAK to Other plan ning systems SNLP, ALPINE, and SIPE by exploring their similarities an d differences.