MadChess 2.0 Beta Build 069 (Bishop Pair)

I added bishop pair evaluation to MadChess 2.0 Beta. The code awards a bonus for possessing two or more bishops, calibrated by game phase.

	private const int _mgBishopPair = 25;
	private const int _egBishopPair = 50;
	// Evaluate bishop pair.
	int mgBishopPair = 0;
	int egBishopPair = 0;
	if (_board.CurrentPosition.WhiteBishops >= 2)
	{
	mgBishopPair += _mgBishopPair;
	egBishopPair += _egBishopPair;
	}
	if (_board.CurrentPosition.BlackBishops >= 2)
	{
	mgBishopPair -= _mgBishopPair;
	egBishopPair -= _egBishopPair;
	}
	// Total static scores.
	int middlegameScore = materialScore + mgLocationScore + mgBishopPair + mgPawns +
	mgPieceMobility + mgKingSafety;
	int endgameScore = materialScore + egLocationScore + egBishopPair + egPawns +
	egPieceMobility + egMaterialTrades;
	// Determine game phase.
	int phaseMaterial = _pawnPhaseMaterial *
	(_board.CurrentPosition.WhitePawns + _board.CurrentPosition.BlackPawns);
	phaseMaterial += _minorPhaseMaterial *
	(_board.CurrentPosition.WhiteMinorPieces + _board.CurrentPosition.BlackMinorPieces);
	phaseMaterial += _rookPhaseMaterial *
	(_board.CurrentPosition.WhiteRooks + _board.CurrentPosition.BlackRooks);
	phaseMaterial += _queenPhaseMaterial *
	(_board.CurrentPosition.WhiteQueens + _board.CurrentPosition.BlackQueens);
	int middlegamePercent = Math.Min((100 * phaseMaterial) / _openingPhaseMaterial, 100);
	int endgamePercent = 100 - middlegamePercent;
	// Taper static score between middlegame and endgame.
	int staticScore = ((middlegameScore * middlegamePercent) + (endgameScore * endgamePercent)) / 100;
	// Negate static score if black is to move.
	return _board.CurrentPosition.WhiteMove ? staticScore : -staticScore;

view raw BishopPair.cs hosted with by GitHub

This added 18 Elo to the playing strength of MadChess 2.0 Beta.

MadChess 2.0                   2242 :   1280 (+561,=259,-460),  53.9 %

vs.                                 :  games (   +,   =,   -),   (%) :   Diff,  SD, CFS (%)
Glass 1.6                           :     80 (  12,  12,  56),  22.5 :   -219,  16,    0.0
RomiChess P3L                       :     80 (   8,  12,  60),  17.5 :   -215,  18,    0.0
OliThink 5.3.2                      :     80 (   7,  10,  63),  15.0 :   -202,  18,    0.0
Myrddin 0.87                        :     80 (  16,  19,  45),  31.9 :   -148,  17,    0.0
Sungorus 1.4                        :     80 (  28,  21,  31),  48.1 :    -68,  10,    0.0
Beowulf 2.4                         :     80 (  38,  17,  25),  58.1 :    +30,  14,   98.5
FireFly v2.6.0                      :     80 (  42,  14,  24),  61.3 :    +31,  10,   99.9
ZCT 0.3.2450                        :     80 (  35,  13,  32),  51.9 :    +36,  11,  100.0
Jazz v444                           :     80 (  30,  19,  31),  49.4 :    +38,  11,  100.0
Wing 2.0                            :     80 (  49,  16,  15),  71.3 :   +120,  11,  100.0
Brainless 1.0                       :     80 (  48,  21,  11),  73.1 :   +136,  19,  100.0
BikJump v2.01                       :     80 (  45,  23,  12),  70.6 :   +141,  12,  100.0
Matheus-2.3                         :     80 (  48,  14,  18),  68.8 :   +159,  14,  100.0
Monarch 1.7                         :     80 (  40,  22,  18),  63.8 :   +178,  11,  100.0
BigLion 2.23w                       :     80 (  58,  12,  10),  80.0 :   +215,  10,  100.0
Sharper 0.17                        :     80 (  57,  14,   9),  80.0 :   +227,  12,  100.0

1. Subversion source code revision
2. Win At Chess position test, 3 seconds per position
3. Bullet chess, 2 min / game + 1 sec / move