Author: Tony Werten
Date: 21:56:20 03/04/04
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On March 04, 2004 at 15:16:43, Mathieu Pagé wrote: >Hi, > >I've just change my minimax algorithm for an AB one. (Yes I know i should have >done this long long time ago, but i did want to keep it simple until it could >play a complete game and understand _all_ the chess rules). > >As expected my engines can search deeper (3-4 more plys) than the old version in >the same time, but the NPS drop dramatically, going from 3.6M nodes/s to a >little bit over 2M nodes/s. It's about 44 % decrease. > >I think it is normal that the nps of Minimax was greater then AB's one because >in AB lot of move are generated, but not searched (so they are not add to the >number of nodes) > >but i think that going from 3.6M to 2M is a big difference. Not really. You spend more time in ordering the moves now. Not only the ordering itself, but also a lot more memory references. ie probing the hashtable, probing killertables, maybe history table. And of coarse, you have to remove those moves from the movelist. Did you already split your move generation in captures and non-captures ? If you have a branching factor of 3 and you search 3 ply more now, you've just speed up the search with factor 27. And you only went 2 times slower to reach that. So still over 13 left. Tony > >Is this behavior normal or did I put an unusual overhead in my algorithm (For >now, i have carefully revised my code and can not see what it is) ? > >TIA :) > >Mathieu Pagé
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