Learning Playing Strategies In

It is believed that chess masters use pattern{based knowledge to analyze a position, followed by a pattern{based controlled search to verify or correct the analysis. In this paper, a rst{order system, called PAL, that can learn patterns in the form of Horn clauses from simple example descriptions and general purpose knowledge is described. It is shown how PAL can learn chess patterns which are beyond the learning capabilities of current inductive systems. The patterns learned by PAL can be used for analysis of positions and for the construction of playing strategies. By taking the learned patterns as attributes for describing examples, a set of rules which decide whether a Pawn can safely be promoted without moving the King in a King and Pawn vs. King endgame, is automatically constructed with a similarity-based learning algorithm. Similarly, a playing strategy for the King and Rook vs. King endgame is automatically constructed with a simple learning algorithm, by following traces of games and using the patterns learned by PAL. Limitations of PAL in particular, and rst{order systems in general, are exposed in domains where a large number of background deenitions may be required for induction. Conclusions and future research directions are given.