Author: Slater Wold
Date: 09:46:04 02/05/04
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On February 05, 2004 at 12:22:44, Bob Durrett wrote: >Referenced by: > >http://www.talkchess.com/forums/1/message.html?345569 > >> An alpha cutoff is what happens when you search the second move, >>> and you prove that if you play that move, your opponent has a move >>> he can play that will produce a score less than your "lower bound" >>> you established for the first move. There is no need to search >>> further. >>> >>> For example, after that +1 on the first move, you try the second >>> move and after trying the first move the opponent has in reply to >>> that move, you discover you _lose_ a pawn. The score is -1.0... >>> There is no need to search other opponent moves to produce a >>> score even lower than -1.00, because you already know this move >>> is at _least_ -1.00 and possibly worse, while the first move is >>> +1.00. You stop searching this move and move on to your third >>> choice... I haven't looked at many programs, other than TSCP, source, but I have a few question about this also... When do most engines call the qsearch? After selecting a move believed to be correct, of at the end of each search tree? The reason I ask is, say you get a cutoff, because the 2nd move produced -1.0 (as in above), but after 4 checks and a capture, you regain that pawn & better position. How do you prevent from not making a move that caused a cutoff, that actually leads to a better position?
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