SearchConstants Namespace Reference

Global constants related to search and evaluation boundaries. More...

Variables
constexpr int	INFINITE = 32000
	Absolute maximum score.
constexpr int	MATE_SCORE = 31500
	Base score for checkmate.
constexpr int	MATE_IN_MAX = MATE_SCORE - 300
	Threshold to detect mating sequences.
constexpr int	TB_WIN_SCORE = 31000
	Base score for a tablebase win.
constexpr int	TB_WIN_IN_MAX = TB_WIN_SCORE - 800
	Threshold to detect tablebase wins.
constexpr int	DRAW_SCORE = 0
	Score for a draw position.
constexpr int	CONTEMPT_FACTOR = 5
	Make draws slightly negative to encourage winning.
constexpr uint8_t	TT_EXACT = 0
	Transposition table entry is an exact score.
constexpr uint8_t	TT_ALPHA = 1
	Transposition table entry is an upper bound (failed low).
constexpr uint8_t	TT_BETA = 2
	Transposition table entry is a lower bound (failed high).
constexpr int	DEFAULT_DEPTH = 100
	Default maximum depth for search.
constexpr int	MAX_PLY = 128
	Maximum supported plies from root.
constexpr int	LMR_MIN_DEPTH = 3
	Minimum depth to consider Late Move Reductions (LMR).
constexpr int	NULL_MOVE_MIN_DEPTH = 4
	Minimum depth to consider Null Move Pruning.
constexpr int	MAX_EXTENSIONS = 8
	Maximum number of search extensions per path.
constexpr int16_t	INVALID_EVAL = 32001
	Special value indicating an uncomputed or invalid static evaluation.

Detailed Description

Global constants related to search and evaluation boundaries.

NOTE: All score constants must fit in int16_t (max 32767) for TT storage. After value_to_tt adds ply (up to MAX_PLY=128), max stored value is ~31628. Hierarchy: INFINITE > MATE_SCORE > MATE_IN_MAX > TB_WIN_SCORE > TB_WIN_IN_MAX > WDL eval (≤30000)

Variable Documentation

CONTEMPT_FACTOR

int SearchConstants::CONTEMPT_FACTOR = 5

constexpr

Make draws slightly negative to encourage winning.

DEFAULT_DEPTH

int SearchConstants::DEFAULT_DEPTH = 100

constexpr

Default maximum depth for search.

DRAW_SCORE

int SearchConstants::DRAW_SCORE = 0

constexpr

Score for a draw position.

INFINITE

int SearchConstants::INFINITE = 32000

constexpr

Absolute maximum score.

INVALID_EVAL

int16_t SearchConstants::INVALID_EVAL = 32001

constexpr

Special value indicating an uncomputed or invalid static evaluation.

LMR_MIN_DEPTH

int SearchConstants::LMR_MIN_DEPTH = 3

constexpr

Minimum depth to consider Late Move Reductions (LMR).

MATE_IN_MAX

int SearchConstants::MATE_IN_MAX = MATE_SCORE - 300

constexpr

Threshold to detect mating sequences.

MATE_SCORE

int SearchConstants::MATE_SCORE = 31500

constexpr

Base score for checkmate.

MAX_EXTENSIONS

int SearchConstants::MAX_EXTENSIONS = 8

constexpr

Maximum number of search extensions per path.

MAX_PLY

int SearchConstants::MAX_PLY = 128

constexpr

Maximum supported plies from root.

NULL_MOVE_MIN_DEPTH

int SearchConstants::NULL_MOVE_MIN_DEPTH = 4

constexpr

Minimum depth to consider Null Move Pruning.

TB_WIN_IN_MAX

int SearchConstants::TB_WIN_IN_MAX = TB_WIN_SCORE - 800

constexpr

Threshold to detect tablebase wins.

TB_WIN_SCORE

int SearchConstants::TB_WIN_SCORE = 31000

constexpr

Base score for a tablebase win.

TT_ALPHA

uint8_t SearchConstants::TT_ALPHA = 1

constexpr

Transposition table entry is an upper bound (failed low).

TT_BETA

uint8_t SearchConstants::TT_BETA = 2

constexpr

Transposition table entry is a lower bound (failed high).

TT_EXACT

uint8_t SearchConstants::TT_EXACT = 0

constexpr

Transposition table entry is an exact score.