Tag: Beta Test

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MadChess 2.0 Beta Build 032 (King Safety)

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I added king safety evaluation to MadChess 2.0 Beta. Defects in king protection (missing pawn shield, semi-open files adjacent to king, squares near king attacked by enemy pieces) are counted, then used as an index into a non-linear piece coordination table. It took me several attempts to calibrate the weights and the non-linear penalty, but eventually I found an improvement. This added 27 Elo to the playing strength of MadChess 2.0 Beta. MadChess 2.0 1904 : 800 (+233,=127,-440), 37.1 % vs. : games ( +, =, -), (%) : Diff, SD, CFS (%) BikJump v2.01 : 100 ( 6, 18,… Continue Reading

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MadChess 2.0 Beta Build 029 (Piece Mobility)

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I added piece mobility evaluation to MadChess 2.0 Beta. The candidate moves of each piece are counted (move legality is not tested) and a non-linear bonus is assigned. Pieces with few moves are penalized. Pieces with many moves are awarded. Assigning a non-linear bonus encourages MadChess to develop all of its pieces, as opposed to maximizing the candidate moves of a few pieces. For example, more centipawns are awarded for increasing the candidate moves of a knight from three to six moves than for increasing the candidate moves of a queen from 14 to 20. This added 64 Elo to… Continue Reading

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MadChess 2.0 Beta Build 027 (Draw By Repetition Bug)

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Yes! I found and exterminated the bug I mentioned in my previous post. I corrected a bug that caused MadChess to play a losing move in a drawn by repetition position. MadChess evaluates the first repetition of a position as drawn, even though the rules of chess state the second repetition is drawn. This search optimization avoids wasting a ply to determine the position is drawn by repetition. MadChess’ recursive search method checks if a position is repeated before searching any moves. If the position is a repeat of an earlier position, the search returns a zero score. I forgot… Continue Reading

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MadChess 2.0 Beta Build 026 (Passed Pawns)

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I added passed pawn evaluation to MadChess 2.0 Beta. No sophisticated evaluation of free (unimpeded) or unstoppable passed pawns. Just a simple tapered evaluation of passed pawns, with a score based on the pawn’s rank. This added 72 Elo to the playing strength of MadChess 2.0 Beta. Bug While watching one of the games, I observed MadChess play a losing move in a drawn by repetition position. It gave a score of mate in zero (which is nonsense), searched to the max depth of 100 plies. I need to hunt down this bug, which likely is robbing MadChess of significant… Continue Reading

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MadChess 2.0 Beta Build 025 (Time Management)

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I added code to measure the time taken to search each ply and calculate if enough time remains to search the next ply. This lessens the number of searches that must be abandoned in the middle of a ply, and the best move from the prior ply played. These abandoned searches waste time. This added 24 Elo to the playing strength of MadChess 2.0 Beta. I believe improved time management will pay greater dividends once I add search reductions and pruning of moves. MadChess 2.0 1694 : 800 (+101,=54,-645), 16.0 % vs. : games ( +, =, -), (%) :… Continue Reading