A Framework for Multi-Criteria Plan Evaluation in Heuristic State-Space Planning

This paper proposes a framework that enhances domain independent heuristic state-space planners with the ability to plan for multiple criteria simultaneously. A criteria hierarchy, together with preferences among them and boundaries over their values, is defined by the knowledge engineer. For the search process in the state-space, a weighted A* strategy is adopted. The heuristic function uses the criteria hierarchy, in order to measure the known accumulated value of the incomplete plan and to estimate the value of the remaining plan. The latter estimation is based on the assignment of multiple value-vectors to the facts of the problem, which estimate the value to achieve the facts from the current state, using alternative paths. A prototype system has been implemented and preliminary performance results have shown that the weights and the scales affect significantly both solution time and plan quality. The framework is general enough, so that it can be applied to all modern heuristic state-