The DerUCP Algorithm Replay(P,C,G,…) Modified version of UCP: loop: if the current partial plan P is a solution then exit G = {refinement goals for P} if there is a case C that matches some g in G then call Replay(P,C,G,…) else nondeterministically select a refinement Replay(P,C,G,…) gC = the first refinement goal in the case C if gC matches a refinement goal g in G then dC = the refinement decision for gC if dC can be applied to g then apply it else exit either call Replay recursively (to replay more of C) or else exit New C P 1st decision 2nd decision 3rd decision not applicable, so exit