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Introduce static evaluation correction history

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Idea from Caissa (https://github.com/Witek902/Caissa) chess engine.

With given pawn structure collect data with how often search result and by how
much it was better / worse than static evalution of position and use it to
adjust static evaluation of positions with given pawn structure. Details:

1. excludes positions with fail highs and moves producing it being a capture;
2. update value is function of not only difference between best value and static
   evaluation but also is multiplied by linear function of depth;
3. maximum update value is maximum value of correction history divided by 2;
4. correction history itself is divided by 32 when applied so maximum value of
   static evaluation adjustment is 32 internal units.

Passed STC:
https://tests.stockfishchess.org/tests/view/658fc7b679aa8af82b955cac
LLR: 2.96 (-2.94,2.94) <0.00,2.00>
Total: 128672 W: 32757 L: 32299 D: 63616
Ptnml(0-2): 441, 15241, 32543, 15641, 470

Passed LTC:
https://tests.stockfishchess.org/tests/view/65903f6979aa8af82b9566f1
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 97422 W: 24626 L: 24178 D: 48618
Ptnml(0-2): 41, 10837, 26527, 11245, 61

closes https://github.com/official-stockfish/Stockfish/pull/4950

Bench: 1157852
This commit is contained in:
Michael Chaly
2023-12-31 10:13:03 +03:00
committed by Disservin
parent 4ff297a6df
commit b4d995d0d9
5 changed files with 98 additions and 26 deletions
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21
src/movepick.h
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@@ -33,12 +33,25 @@
namespace Stockfish {
constexpr int PAWN_HISTORY_SIZE = 512; // has to be a power of 2
constexpr int PAWN_HISTORY_SIZE = 512; // has to be a power of 2
constexpr int CORRECTION_HISTORY_SIZE = 16384; // has to be a power of 2
constexpr int CORRECTION_HISTORY_LIMIT = 1024;
static_assert((PAWN_HISTORY_SIZE & (PAWN_HISTORY_SIZE - 1)) == 0,
"PAWN_HISTORY_SIZE has to be a power of 2");
inline int pawn_structure(const Position& pos) { return pos.pawn_key() & (PAWN_HISTORY_SIZE - 1); }
static_assert((CORRECTION_HISTORY_SIZE & (CORRECTION_HISTORY_SIZE - 1)) == 0,
"CORRECTION_HISTORY_SIZE has to be a power of 2");
enum PawnHistoryType {
Normal,
Correction
};
template<PawnHistoryType T = Normal>
inline int pawn_structure_index(const Position& pos) {
return pos.pawn_key() & ((T == Normal ? PAWN_HISTORY_SIZE : CORRECTION_HISTORY_SIZE) - 1);
}
// StatsEntry stores the stat table value. It is usually a number but could
// be a move or even a nested history. We use a class instead of a naked value
@@ -122,6 +135,10 @@ using ContinuationHistory = Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB>
// PawnHistory is addressed by the pawn structure and a move's [piece][to]
using PawnHistory = Stats<int16_t, 8192, PAWN_HISTORY_SIZE, PIECE_NB, SQUARE_NB>;
// CorrectionHistory is addressed by color and pawn structure
using CorrectionHistory =
Stats<int16_t, CORRECTION_HISTORY_LIMIT, COLOR_NB, CORRECTION_HISTORY_SIZE>;
// MovePicker class is used to pick one pseudo-legal move at a time from the
// current position. The most important method is next_move(), which returns a
// new pseudo-legal move each time it is called, until there are no moves left,