For DERSNLP+EBL, the skeletal plan is extended first, prior to recovery. This plan is backtracked over only after the search process fails to refine it into a full solution to the new problem. This strategy requires a depth limit to be placed on the search tree. Otherwise skeletal plan extension may continue indefinitely, and the planning algorithm becomes incomplete. An eager extension strategy is not, however, linked to a particular search method. For example, it may be used with best-first, depth-first or iterative deepening search. These different search methods are used in the exploration of the subtree under the skeletal plan, prior to backtracking over this plan. Once the skeletal plan is found to fail, the recovery phase that is initiated merely involves exploring the siblings of the replayed path. Like extension, recovery is not linked to a particular search strategy.