A Domain-Independent Algorithm for Plan Adaptation

TL;DR

This paper introduces a domain-independent, systematic, and complete plan adaptation algorithm that modifies existing plans efficiently by searching a plan graph, applicable across various planning paradigms.

Contribution

It presents a novel, general algorithm for plan adaptation that is sound, complete, and systematic, unifying different planning approaches.

Findings

Algorithm is sound and complete

Can adapt plans by retracting constraints and steps

Compared favorably with existing adaptation algorithms

Abstract

The paradigms of transformational planning, case-based planning, and plan debugging all involve a process known as plan adaptation - modifying or repairing an old plan so it solves a new problem. In this paper we provide a domain-independent algorithm for plan adaptation, demonstrate that it is sound, complete, and systematic, and compare it to other adaptation algorithms in the literature. Our approach is based on a view of planning as searching a graph of partial plans. Generative planning starts at the graph's root and moves from node to node using plan-refinement operators. In planning by adaptation, a library plan - an arbitrary node in the plan graph - is the starting point for the search, and the plan-adaptation algorithm can apply both the same refinement operators available to a generative planner and can also retract constraints and steps from the plan. Our algorithm's completeness ensures that the adaptation algorithm will eventually search the entire graph and its systematicity ensures that it will do so without redundantly searching any parts of the graph.