From ca4e78db8db1288eb5c8deecb9bdf402f53fdc98 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Sun, 15 Mar 2009 16:44:12 +0100 Subject: [PATCH] Revert NULL move beta corrections After testing result is bad -25 ELO --- src/evaluate.cpp | 34 ++++++++++++++++++---------------- src/evaluate.h | 1 - src/search.cpp | 20 ++------------------ 3 files changed, 20 insertions(+), 35 deletions(-) diff --git a/src/evaluate.cpp b/src/evaluate.cpp index 4745da02..c397671c 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -289,6 +289,7 @@ namespace { void evaluate_space(const Position &p, Color us, EvalInfo &ei); inline Value apply_weight(Value v, int w); + Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]); int count_1s_8bit(Bitboard b); @@ -527,22 +528,6 @@ void read_weights(Color us) { } -/// scale_by_game_phase() interpolates between a middle game and an endgame -/// score, based on game phase. It also scales the return value by a -/// ScaleFactor array. - -Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) { - - assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE); - assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE); - assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME); - - ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]); - - Value result = Value(int((mv * ph + ev * (128 - ph)) / 128)); - return Value(int(result) & ~(GrainSize - 1)); -} - namespace { // evaluate_common() computes terms common to all pieces attack @@ -1159,6 +1144,23 @@ namespace { } + // scale_by_game_phase() interpolates between a middle game and an endgame + // score, based on game phase. It also scales the return value by a + // ScaleFactor array. + + Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) { + + assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE); + assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE); + assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME); + + ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]); + + Value result = Value(int((mv * ph + ev * (128 - ph)) / 128)); + return Value(int(result) & ~(GrainSize - 1)); + } + + // count_1s_8bit() counts the number of nonzero bits in the 8 least // significant bits of a Bitboard. This function is used by the king // shield evaluation. diff --git a/src/evaluate.h b/src/evaluate.h index 1e97fd35..b95aa15d 100644 --- a/src/evaluate.h +++ b/src/evaluate.h @@ -105,7 +105,6 @@ extern Value quick_evaluate(const Position &pos); extern void init_eval(int threads); extern void quit_eval(); extern void read_weights(Color sideToMove); -extern Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]); #endif // !defined(EVALUATE_H_INCLUDED) diff --git a/src/search.cpp b/src/search.cpp index 92d2c75e..549f19e2 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -149,16 +149,6 @@ namespace { // evaluation of the position is more than NullMoveMargin below beta. const Value NullMoveMargin = Value(0x300); - //Null move search refutes move when Nullvalue >= Beta - Delta. Index is depth - //in full plies. Last index is 9+. - const Value NullMoveDeltaMidgame[] = - { Value(-8), Value( 6), Value(-15), Value( 9), Value(21), - Value(34), Value(54), Value( 59), Value(61), Value(61) }; - - const Value NullMoveDeltaEndgame[] = - { Value( 6), Value( 0), Value(-13), Value(-9), Value(-35), - Value(12), Value(24), Value( 9), Value( 5), Value( 5) }; - // Pruning criterions. See the code and comments in ok_to_prune() to // understand their precise meaning. const bool PruneEscapeMoves = false; @@ -1207,19 +1197,13 @@ namespace { && ok_to_do_nullmove(pos) && approximateEval >= beta - NullMoveMargin) { - //Calculate correct delta. Idea and tuning from Joona Kiiski. - ScaleFactor factor[2] = { SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL }; - Phase phase = pos.game_phase(); - int i = Min(depth / OnePly, 9); - Value delta = scale_by_game_phase(NullMoveDeltaMidgame[i], NullMoveDeltaEndgame[i], phase, factor); - ss[ply].currentMove = MOVE_NULL; StateInfo st; pos.do_null_move(st); int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction - Value nullValue = -search(pos, ss, -(beta-delta-1), depth-R*OnePly, ply+1, false, threadID); + Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); pos.undo_null_move(); @@ -1227,7 +1211,7 @@ namespace { { /* Do not return unproven mates */ } - else if (nullValue >= beta - delta) + else if (nullValue >= beta) { if (depth < 6 * OnePly) return beta; -- 2.39.5