From: FauziAkram Date: Mon, 8 May 2017 04:03:59 +0000 (-0700) Subject: Linear Protector bonus by distance X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;ds=sidebyside;h=6b4959e3e00035dbcabd74a6d49ce7d04008d62c;p=stockfish Linear Protector bonus by distance Replacing the old Protector table with a simple linear formula which takes into account a different slope for each different piece type. The idea of this simplification of Protector is originated by Alain (Rocky) STC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 70382 W: 12859 L: 12823 D: 44700 LTC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 61554 W: 8098 L: 8031 D: 45425 Bench: 6107863 Closes #1099 --- diff --git a/src/evaluate.cpp b/src/evaluate.cpp index 4351fe2e..9202c9ed 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -174,14 +174,8 @@ namespace { S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10) }; - // Protector[PieceType-2][distance] contains a protecting bonus for our king, - // indexed by piece type and distance between the piece and the king. - const Score Protector[][8] = { - { S(0, 0), S( 7, 9), S( 7, 1), S( 1, 5), S(-10,-4), S( -1,-4), S( -7,-3), S(-16,-10) }, // Knight - { S(0, 0), S(11, 8), S(-7,-1), S(-1,-2), S( -1,-7), S(-11,-3), S( -9,-1), S(-16, -1) }, // Bishop - { S(0, 0), S(10, 0), S(-2, 2), S(-5, 4), S( -6, 2), S(-14,-3), S( -2,-9), S(-12, -7) }, // Rook - { S(0, 0), S( 3,-5), S( 2,-5), S(-4, 0), S( -9,-6), S( -4, 7), S(-13,-7), S(-10, -7) } // Queen - }; + // KingProtector[PieceType-2] * "distance to own king" determines a bonus for each piece. + const Score KingProtector[] = {S(-3, -5), S(-4, -3), S(-3, 0), S(-1, 1) }; // Assorted bonuses and penalties used by evaluation const Score MinorBehindPawn = S( 16, 0); @@ -299,8 +293,7 @@ namespace { mobility[Us] += MobilityBonus[Pt-2][mob]; - // Bonus for this piece as a king protector - score += Protector[Pt-2][distance(s, pos.square(Us))]; + score += KingProtector[Pt-2] * distance(s, pos.square(Us)); if (Pt == BISHOP || Pt == KNIGHT) { diff --git a/src/types.h b/src/types.h index 417f4815..2709d77f 100644 --- a/src/types.h +++ b/src/types.h @@ -184,10 +184,10 @@ enum Value : int { VALUE_MATED_IN_MAX_PLY = -VALUE_MATE + 2 * MAX_PLY, PawnValueMg = 188, PawnValueEg = 248, - KnightValueMg = 753, KnightValueEg = 832, - BishopValueMg = 814, BishopValueEg = 890, - RookValueMg = 1285, RookValueEg = 1371, - QueenValueMg = 2513, QueenValueEg = 2648, + KnightValueMg = 764, KnightValueEg = 848, + BishopValueMg = 826, BishopValueEg = 891, + RookValueMg = 1282, RookValueEg = 1373, + QueenValueMg = 2526, QueenValueEg = 2646, MidgameLimit = 15258, EndgameLimit = 3915 };