ICGA Torneio

In Greek mythology, Cheiron was the wisest of all centaurs and the teacher of many heroes. The program Cheiron is written in C. It is an alpha-beta program using most of the known state-of-the-art heuristics including killer heuristics, transposition table, aspiration search, plausible move ordering, iterative deepening, selective deepening etc. Null moves, however, are not used. The quiescence search is quite large and examines some tactical motifs, particularly mating and promotion threats. Apart from the move generator, the evaluation function is the most expensive part of the program. It examines the pawn structure, king's security, static positions of the pieces, everlasting knights etc. as well as special situations in the endgame (e.g. there are positions when two pawns are more worth than a rook). On a Pentium 90MHz the program will search about 10.000 nodes per second. Cheiron is more a positional playing than a tactical playing program. Cheiron uses an opening book containing about 12,000 positions to get a good start into the game. Using the Bednorz-Toennissen test, Cheiron has an estimated rating of 2100 ELO on a 50MHz PC. Tournament results against humans supports this number. Originally, the program was developed for Unix boxes, but a version has been developed with a graphical interface using Turbo C in a DOS-Windows 3.1 environment.