Author: Miguel A. Ballicora
Date: 22:34:46 12/25/02
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On December 25, 2002 at 15:18:29, Robert Hyatt wrote: >On December 25, 2002 at 10:46:17, Dieter Buerssner wrote: > >>On December 24, 2002 at 23:05:09, Robert Hyatt wrote: >> >>>[...] Why don't you go read Knuth/Moore's paper on >>>alpha beta. There you will find that move ordering does _not_ affect the >>>final score, only the size of the tree. Something every senion-level computer >>>science student should know. >> >>I think, in most modern chess programs, move ordering can affect the final >>score. Reasons can be extensions/pruning/hash tables. >> >>Regards, >>Dieter > >If move ordering affects extensions or pruning, _something_ is broken. As >that violates the basic premise of alpha/beta... I am really surprised by this statement. Any pruning or extension that depends on alpha will be affected by the move ordering. With different move ordering, the same position might face different bounds, hence, different extensions could be triggered. > >Hashing _can_ cause quirks, but it actually is more important to search _worse_ >moves first and then graft those search results on to better searches. That is >how we solve fine 70 faster than we should. If the tree were ordered >perfectly it takes 26 plies, period... IMHO, faster in plies does not mean faster in nodes (time). With terrible move ordering you could solve a position in less plies but it could be in more nodes than with good move ordering. Miguel
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