Author: Ryan B.
Date: 02:45:06 11/05/05
Go up one level in this thread
On November 05, 2005 at 04:27:59, Thorsten Czub wrote: >that would be nice for tuning the style. History pruning is not pruning it reduces move with a low move value. The higher the threshold the more moves get reduced. Futility Pruning, the idea is that if material score + margin can not get to alpha don't bother to go further. Because this is unsafe it is only don't at depth remaining 1 and depth remaining 2 with a larger margin. At Depth remaining 3 it would use a larger margin and reduce instead of cut but I do not think limited razoring works in Toga. In general lower futility margins make a program more tactical and higher values are safer and better for positional play. Delta pruning is kind of like futility pruning only in Q's and in my experience safer. Material is the percent of the piece values to add in eval base values are: Pawn = 100 Knight = 325 Bishop = 325 Rook = 500 Queen = 1000 Piece Activity is the percent of the mobility to add in eval base vales are: // opening knight: (attackable_squares-4) * 4 bishop: (attackable_squares-6) * 5 rook: (attackable_squares-7) * 2 queen: (attackable_squares-13) * 1 // endgame knight: (attackable_squares-4) * 4 bishop: (attackable_squares-6) * 5 rook: (attackable_squares-7) * 4 queen: (attackable_squares-13) * 2 King Safety is the percent of the king attack and king shielding to add the eval. I don't remember the algorithm for this off hand. Pawn Structure is the percent of pawn weakness values to be added to eval. base values are: // opening doubled_pawn: -10 isolated_pawn: -10 isolated_pawn_open: -20 // this is on open file backward_pawn: -8 backward_pawn_open: -16 // on open file candidate_min: 5 // will become passed candidate_max: 55 // this scales up by rank // endgame doubled_pawn: -20 isolated_pawn: -20 backward_pawn: -10 candidate_min: 10 // will become passed candidate_max: 110 // this scales up by rank Passed Pawns is the percent of passed pawns value to add to eval. base values are: // opening passed_min: 10 passed_max: 70 // scaled by rank // endgame passed_min: 20 passed_max: 140 Toga Lazy Eval Margin if the material score + margin above beta or score - margin below alpha used to skip a large part of the eval including king safety and passed pawns. Does not sound safe but it seems to work in Toga. Just like with Futility pruning lower value gets a more tactical result and higher more positional. Exchange bonus is a bonus for having more pieces. I goal is to not trade 2 minors for a rook and a pawn or a minor for 3 pawns. I have not seen that fruit 2.1 had issues with this anyway though. Toga King Safety Margin, I think this is the material value needed to add more value to king attack.
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