Author: scott farrell
Date: 20:14:56 01/13/03
Guys, I am after some comments here. I have some code and ideas I need people to help validate. My code uses the detect draw-by-rep routine/hash etc. Currently I only run this when there is a bishop or knight or less on the board, as I dont know how safe the code is yet. It compares the pawn hash to all previous pawn hashes in the tree, if it finds a hit, and the material is the same , it scores it as 0.0, meaning: if the pawns are in the same config, and material is unchanged, then with all the searching you have done you cant progress at all, just call it a draw. Does anyone do any blockade checking in their code? Is my idea similar, different, stupid. My chompster lost a drawn game recently, the position was similar to this below. It was down material, and found a long sequence of moves where it could get 1 pawn back, and so it did, at the expense of opening the postion and then loosing which was beyond the horizon. To a human it is clearly a draw, just blockade !!!. This is an over simplfied position, so it is simple enough for me personally to work out. Clearly either Ke3 or Be3 draws. Ruffian thinks the score is -1.1 for white at about 16 plies and 30 secs. When I enable my new blockade code it sees a score of 0.0 for Kd3 immediately - which is great. What is even better is that for black to move in the same position without the blockade code it thinks it is winning big time, and just shuffles pieces around, horizoning the draw-by-rep, and doesnt quite get to 100 plies to see draw by fifty moves. With the blockade code it first thinks of e3 as the only "progress" it can make against the blockade, then it tries some stalling moves in between to push things over the horizon (oops). After a fail low on depth 8, it realises it is blockaded, and after a research at full width it returns Bc6 with a score of 0.08 (I think this is just an artifact of lazyeval and should be 0.0), and knows white is going to play Ke3 immediately. I think this is amazing progress for my chompster, and an extra 5 lines of code added ... amazing !!!! Maybe I can take some nice draws in CCT5 against ruffian !!!! ... I wish :) [D] 8/8/1B2k3/1b2p3/4p3/3p4/3P1K2/8 w - - 0 1 [D] 8/8/1B2k3/1b2p3/4p3/3p4/3P1K2/8 b - - 0 1
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