Author: Robert Hyatt
Date: 11:43:31 06/03/99
Go up one level in this thread
On June 03, 1999 at 12:59:02, William Bryant wrote: >Every time I try to improve my program, I seem to break it in innumerable ways. > >The killer move heuristic should be rather easy to implement. > >At every ply, any move that generates a cutoff (I interpret as a beta cutoff, a >fail high), this move is added to the current killer table. > >Is it an alpha cutoff (score > alpha) more appropriate? > score > alpha isn't a cutoff, unless it is also >= beta. There are two reasons for killer updates. (1) current move fails high (>= beta); (2) current move gets backed up as a best move (ie score > alpha, < beta, so it is a potential PV move). >Also, does this move automatically displace previous killer moves, or do you use >some qualifier such as the search score, keeping the moves with the greates >score? > I store 2 killers. when one of the two causes a cutoff, it is moved to the front to try the next time. New moves always replace the second killer. >Finally, in using the killer moves for move ordering the ranking I am using is: >1. Hash Table Move >2. PV Move (in not the same as #1) >3. Captures with a net positive score (captured piece > capturing piece) > Promotions >4. Killer moves and Captures with an equal score (exchange) >5. Loosing Captures >6. All other moves--sorted by the history heuristic. get rid of 5. Let those drop into 6... > >Any help will be appreciated, I am missing something simple because this is >slowing down, not speeding up my search. > > >William >wbryant@ix.netcom.com
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.