The SHOP

SHOP's preconditions can include logical inferences, SHOP's expressive power can be used to create Here, we summarize the SHOP algorithm's primary SHOP algorithm is shown in figure 1. S is a state, T is a list of tasks, and D is the knowledge base (methods, operators, and Horn-clause axioms). As long as the procedure for inferring m's preconditions from S is a sound and complete inference procedure (such as Horn-clause theorem proving), the For example, the Horn clauses can include calls to attached procedures for numeric computations (for example, "distance(UofMD,BWI) 50" in the previous example), or (in some of the implementations) any other procedure calls defined by the user. In our experiments (Nau et al. 1999), SHOP generated SHOP's higher level of expressivity made PLAN and SHOP was not too different. We intend to make more optimizations in the near future. HICAP is shown in figure 4. HICAP (Aha and Breslow 1997).