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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2018 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
*/
#include <algorithm>
+#include <cfloat>
+#include <cmath>
#include "search.h"
#include "timeman.h"
enum TimeType { OptimumTime, MaxTime };
- int remaining(int myTime, int myInc, int moveOverhead, int movesToGo,
- int moveNum, bool ponder, TimeType type) {
+ const int MoveHorizon = 50; // Plan time management at most this many moves ahead
+ const double MaxRatio = 7.09; // When in trouble, we can step over reserved time with this ratio
+ const double StealRatio = 0.35; // However we must not steal time from remaining moves over this ratio
- if (myTime <= 0)
- return 0;
- double ratio; // Which ratio of myTime we are going to use
+ // move_importance() is a skew-logistic function based on naive statistical
+ // analysis of "how many games are still undecided after n half-moves". Game
+ // is considered "undecided" as long as neither side has >275cp advantage.
+ // Data was extracted from the CCRL game database with some simple filtering criteria.
- // Usage of increment follows quadratic distribution with the maximum at move 25
- double inc = myInc * std::max(55.0, 120 - 0.12 * (moveNum - 25) * (moveNum - 25));
+ double move_importance(int ply) {
- // In moves-to-go we distribute time according to a quadratic function with
- // the maximum around move 20 for 40 moves in y time case.
- if (movesToGo)
- {
- ratio = (type == OptimumTime ? 1.0 : 6.0) / std::min(50, movesToGo);
+ const double XScale = 7.64;
+ const double XShift = 58.4;
+ const double Skew = 0.183;
- if (moveNum <= 40)
- ratio *= 1.1 - 0.001 * (moveNum - 20) * (moveNum - 20);
- else
- ratio *= 1.5;
+ return pow((1 + exp((ply - XShift) / XScale)), -Skew) + DBL_MIN; // Ensure non-zero
+ }
+
+ template<TimeType T>
+ int remaining(int myTime, int movesToGo, int ply, int slowMover) {
- if (movesToGo > 1)
- ratio = std::min(0.75, ratio);
+ const double TMaxRatio = (T == OptimumTime ? 1 : MaxRatio);
+ const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
- ratio *= 1 + inc / (myTime * 8.5);
- }
- // Otherwise we increase usage of remaining time as the game goes on
- else
- {
- double k = 1 + 20 * moveNum / (500.0 + moveNum);
- ratio = (type == OptimumTime ? 0.017 : 0.07) * (k + inc / myTime);
- }
+ double moveImportance = (move_importance(ply) * slowMover) / 100;
+ double otherMovesImportance = 0;
- int time = int(std::min(1.0, ratio) * std::max(0, myTime - moveOverhead));
+ for (int i = 1; i < movesToGo; ++i)
+ otherMovesImportance += move_importance(ply + 2 * i);
- if (type == OptimumTime && ponder)
- time = 5 * time / 4;
+ double ratio1 = (TMaxRatio * moveImportance) / (TMaxRatio * moveImportance + otherMovesImportance);
+ double ratio2 = (moveImportance + TStealRatio * otherMovesImportance) / (moveImportance + otherMovesImportance);
- return time;
+ return int(myTime * std::min(ratio1, ratio2)); // Intel C++ asks for an explicit cast
}
} // namespace
/// inc > 0 && movestogo == 0 means: x basetime + z increment
/// inc > 0 && movestogo != 0 means: x moves in y minutes + z increment
-void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
-{
- int moveOverhead = Options["Move Overhead"];
- int npmsec = Options["nodestime"];
- bool ponder = Options["Ponder"];
+void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
+
+ int minThinkingTime = Options["Minimum Thinking Time"];
+ int moveOverhead = Options["Move Overhead"];
+ int slowMover = Options["Slow Mover"];
+ int npmsec = Options["nodestime"];
// If we have to play in 'nodes as time' mode, then convert from time
// to nodes, and use resulting values in time management formulas.
limits.npmsec = npmsec;
}
- int moveNum = (ply + 1) / 2;
-
startTime = limits.startTime;
- optimumTime = remaining(limits.time[us], limits.inc[us], moveOverhead,
- limits.movestogo, moveNum, ponder, OptimumTime);
- maximumTime = remaining(limits.time[us], limits.inc[us], moveOverhead,
- limits.movestogo, moveNum, ponder, MaxTime);
+ optimumTime = maximumTime = std::max(limits.time[us], minThinkingTime);
+
+ const int MaxMTG = limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon;
+
+ // We calculate optimum time usage for different hypothetical "moves to go"-values
+ // and choose the minimum of calculated search time values. Usually the greatest
+ // hypMTG gives the minimum values.
+ for (int hypMTG = 1; hypMTG <= MaxMTG; ++hypMTG)
+ {
+ // Calculate thinking time for hypothetical "moves to go"-value
+ int hypMyTime = limits.time[us]
+ + limits.inc[us] * (hypMTG - 1)
+ - moveOverhead * (2 + std::min(hypMTG, 40));
+
+ hypMyTime = std::max(hypMyTime, 0);
+
+ int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
+ int t2 = minThinkingTime + remaining<MaxTime >(hypMyTime, hypMTG, ply, slowMover);
+
+ optimumTime = std::min(t1, optimumTime);
+ maximumTime = std::min(t2, maximumTime);
+ }
+
+ if (Options["Ponder"])
+ optimumTime += optimumTime / 4;
}
projects / stockfish / blobdiff