A Transformational Analysis of the EBL Utility Problem in Soar

Efficiency is a major concern for all planning systems. One way of achieving efficiency is the application of learning techniques to speed up planning. Accordingly, there has been considerable amount of research on applying EBL (explanation-based learning) techniques to planning. However, EBL is known to suffer from the utility problem, where the cost of using the learned knowledge overwhelms its benefit. This paper shows how the cost increase of a learned rule in an EBL system can be analyzed by characterizing the learning process as a sequence of transformations from a planning (problem solving) episode to a learned rule. The analysis of how the cost changes through the transformations can be a useful tool for revealing the sources of cost increase in the learning system. In this paper, we focus on the Soar planning system which uses a variant of EBL called chunking. The chunking process has been decomposed into a sequence of transformations from the planning to a chunk. By analyzin..