► Chapter 5 introduced a methodology for “intelligent” or “heuristic” search. To this point we have used heuristic search only in single-person problem solving. ► Chapter 6 proposes using heuristics in two-person competitive situations. In the first three sections, ► Chap. 6 , presents several heuristic measures that can improve search in two-person zero-sum games. These techniques include the minimax algorithm and the alpha-beta pruning of a search space. ► Sect. 6.4 analyzes heuristic search to determine several theoretical properties. These include how heuristic search can be used in multi-player games. We then consider whether it can be determined that a particular search strategy will guarantee a minimal path length solution if such a solution exists. Further, ► Sect. 6.4, demonstrates how one heuristic can be “better” than a second, in that it searches a smaller component of the space to arrive at a minimal path solution. Finally, ► Sect. 6.5 summarizes the relationships between the branching factor of a graph and the number of nodes searched and the costs of heuristic evaluation compared to uninformed search.