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BadFish/src/search.h
Stefan Geschwentner 8fec883471 Tweak Late Move Reduction at root
Maintain best move counter at the root and allow there only moves which has a counter
of zero for Late Move Reduction. For compensation only the first three moves are excluded
from Late Move Reduction per default instead the first four moves.

What we can further do:

- here we use a simple counting scheme but perhaps some aging to fade out early iterations
  could be helpful
- use the best move counter also at inner nodes for LMR and/or pruning

STC:
LLR: 2.95 (-2.94,2.94) [0.50,4.50]
Total: 17414 W: 3984 L: 3733 D: 9697
http://tests.stockfishchess.org/tests/view/5d6234bb0ebc5939d09f2aa2

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,3.50]
Total: 38058 W: 6448 L: 6166 D: 25444
http://tests.stockfishchess.org/tests/view/5d62681a0ebc5939d09f2f27

Closes https://github.com/official-stockfish/Stockfish/pull/2282

Bench: 3568210
2019-08-26 08:49:55 +02:00

109 lines
3.2 KiB
C++

/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SEARCH_H_INCLUDED
#define SEARCH_H_INCLUDED
#include <vector>
#include "misc.h"
#include "movepick.h"
#include "types.h"
class Position;
namespace Search {
/// Threshold used for countermoves based pruning
constexpr int CounterMovePruneThreshold = 0;
/// Stack struct keeps track of the information we need to remember from nodes
/// shallower and deeper in the tree during the search. Each search thread has
/// its own array of Stack objects, indexed by the current ply.
struct Stack {
Move* pv;
PieceToHistory* continuationHistory;
int ply;
Move currentMove;
Move excludedMove;
Move killers[2];
Value staticEval;
int statScore;
int moveCount;
};
/// RootMove struct is used for moves at the root of the tree. For each root move
/// we store a score and a PV (really a refutation in the case of moves which
/// fail low). Score is normally set at -VALUE_INFINITE for all non-pv moves.
struct RootMove {
explicit RootMove(Move m) : pv(1, m) {}
bool extract_ponder_from_tt(Position& pos);
bool operator==(const Move& m) const { return pv[0] == m; }
bool operator<(const RootMove& m) const { // Sort in descending order
return m.score != score ? m.score < score
: m.previousScore < previousScore;
}
Value score = -VALUE_INFINITE;
Value previousScore = -VALUE_INFINITE;
int selDepth = 0;
int tbRank = 0;
int bestMoveCount = 0;
Value tbScore;
std::vector<Move> pv;
};
typedef std::vector<RootMove> RootMoves;
/// LimitsType struct stores information sent by GUI about available time to
/// search the current move, maximum depth/time, or if we are in analysis mode.
struct LimitsType {
LimitsType() { // Init explicitly due to broken value-initialization of non POD in MSVC
time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] = npmsec = movetime = TimePoint(0);
movestogo = depth = mate = perft = infinite = 0;
nodes = 0;
}
bool use_time_management() const {
return !(mate | movetime | depth | nodes | perft | infinite);
}
std::vector<Move> searchmoves;
TimePoint time[COLOR_NB], inc[COLOR_NB], npmsec, movetime, startTime;
int movestogo, depth, mate, perft, infinite;
int64_t nodes;
};
extern LimitsType Limits;
void init();
void clear();
} // namespace Search
#endif // #ifndef SEARCH_H_INCLUDED