From b24bd762b2aff6cac30e1ae673775ea6f6aa8d11 Mon Sep 17 00:00:00 2001 From: Rocky640 Date: Tue, 1 Aug 2017 18:36:33 -0700 Subject: [PATCH] Rework the "unsupported" penalty into a "supported" bonus A pawn (according to all the searched positions of a bench run) is not supported 85% of the time, (in current master it is either isolated, backward or "unsupported"). So it made sense to try moving the S(17, 8) "unsupported" penalty value into the base pawn value hoping for a more representative pawn value, and accordingly a) adjust backward and isolated so that they stay more or less the same as master b) increase the mg connected bonus in the supported case by S(17, 0) and let the Connected formula find a suitable eg value according to rank. Tested as a simplification SPRT(-3, 1) Passed STC http://tests.stockfishchess.org/tests/view/5970dbd30ebc5916ff649dd6 LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 19613 W: 3663 L: 3540 D: 12410 Passed LTC http://tests.stockfishchess.org/tests/view/597137780ebc5916ff649de3 LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 24721 W: 3306 L: 3191 D: 18224 Bench: 5581946 Closes #1179 --- src/pawns.cpp | 36 +++++++++++++++--------------------- src/types.h | 2 +- 2 files changed, 16 insertions(+), 22 deletions(-) diff --git a/src/pawns.cpp b/src/pawns.cpp index b8f82cff..510ee167 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -32,16 +32,13 @@ namespace { #define S(mg, eg) make_score(mg, eg) // Isolated pawn penalty by opposed flag - const Score Isolated[] = { S(45, 40), S(30, 27) }; + const Score Isolated[] = { S(27, 30), S(13, 18) }; // Backward pawn penalty by opposed flag - const Score Backward[] = { S(56, 33), S(41, 19) }; + const Score Backward[] = { S(40, 26), S(24, 12) }; - // Unsupported pawn penalty for pawns which are neither isolated or backward - const Score Unsupported = S(17, 8); - - // Connected pawn bonus by opposed, phalanx, twice supported and rank - Score Connected[2][2][2][RANK_NB]; + // Connected pawn bonus by opposed, phalanx, #support and rank + Score Connected[2][2][3][RANK_NB]; // Doubled pawn penalty const Score Doubled = S(18, 38); @@ -99,7 +96,7 @@ namespace { const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST); Bitboard b, neighbours, stoppers, doubled, supported, phalanx; - Bitboard lever, leverPush, connected; + Bitboard lever, leverPush; Square s; bool opposed, backward; Score score = SCORE_ZERO; @@ -134,7 +131,6 @@ namespace { neighbours = ourPawns & adjacent_files_bb(f); phalanx = neighbours & rank_bb(s); supported = neighbours & rank_bb(s - Up); - connected = supported | phalanx; // A pawn is backward when it is behind all pawns of the same color on the // adjacent files and cannot be safely advanced. @@ -150,7 +146,7 @@ namespace { // stopper on adjacent file which controls the way to that rank. backward = (b | shift(b & adjacent_files_bb(f))) & stoppers; - assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours)); + assert(!(backward && (forward_ranks_bb(Them, s + Up) & neighbours))); } // Passed pawns will be properly scored in evaluation because we need @@ -173,18 +169,15 @@ namespace { } // Score this pawn - if (!neighbours) + if (supported | phalanx) + score += Connected[opposed][!!phalanx][popcount(supported)][relative_rank(Us, s)]; + + else if (!neighbours) score -= Isolated[opposed]; else if (backward) score -= Backward[opposed]; - else if (!supported) - score -= Unsupported; - - if (connected) - score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)]; - if (doubled && !supported) score -= Doubled; @@ -209,12 +202,13 @@ void init() { for (int opposed = 0; opposed <= 1; ++opposed) for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (int apex = 0; apex <= 1; ++apex) + for (int support = 0; support <= 2; ++support) for (Rank r = RANK_2; r < RANK_8; ++r) { - int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; - v += (apex ? v / 2 : 0); - Connected[opposed][phalanx][apex][r] = make_score(v, v * (r-2) / 4); + int v = 17 * support; + v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; + + Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4); } } diff --git a/src/types.h b/src/types.h index c24f2209..3260b903 100644 --- a/src/types.h +++ b/src/types.h @@ -183,7 +183,7 @@ enum Value : int { VALUE_MATE_IN_MAX_PLY = VALUE_MATE - 2 * MAX_PLY, VALUE_MATED_IN_MAX_PLY = -VALUE_MATE + 2 * MAX_PLY, - PawnValueMg = 188, PawnValueEg = 248, + PawnValueMg = 171, PawnValueEg = 240, KnightValueMg = 764, KnightValueEg = 848, BishopValueMg = 826, BishopValueEg = 891, RookValueMg = 1282, RookValueEg = 1373, -- 2.39.2