A survey of tsume-shogi programs using variable-depth search

Abstract

Recently, a number of programs have been developed that successfully apply variable-depth search to find solutions for mating problems in Japanese chess, called tsume shogi. Publications on this research domain have been written mainly in Japanese. To present the findings of this research to a wider audience, we compare six different tsume programs. To find the solutions of difficult tsume-shogi problems with solution sequences longer than 20 plies, we will see that variable- depth search and hashing to deal with a combination of transposition, domination and simulation leads to strong tsume-shogi programs that outperform human experts, both in speed and in the number of problems for which the solution can be found. The best program has been able to solve Microcosmos, a tsume-shogi problem with a solution sequence of 1525 plies.