MadChess 3.0 Beta Build 093 (Staged Move Generation)

I increased the speed at which MadChess 3.0 Beta examines nodes by implementing staged move generation. Previously, in the main search, the chess engine would generate all pseudo-legal moves, sort them by move priority, then iterate through them: testing move legality (does move expose own king to check) and playing the legal moves. This is wasteful if a beta cutoff occurs early in the move list. Usually a capture is responsible for a beta cutoff, so time is wasted generating non-captures. Now the chess engine generates moves in stages. I could have implemented more stages (QueenCaptures, RookCaptures, BishopKnightCaptures, etc) but… Continue Reading

MadChess 2.0 Beta Build 023 (Delay Move Generation)

I added code to delay move generation if a cached position specifies a best move. The best move is played first. If it causes a beta cutoff, the expense of generating moves is avoided. If not, moves are generated and searched, skipping the best move, which has already been searched. Also, I corrected a bug that caused all searches to use an infinite aspiration window.  The corrected code will search the first ply using an infinite aspiration window, then search subsequent plies with a narrow window around the first ply’s score.  If the score of subsequent searches lies on an… Continue Reading