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BadFish/src/ucioption.cpp
Stéphane Nicolet 254d995e18 Contempt 20
Set the default contempt value of Stockfish to 20 centipawns.

The contempt feature of Stockfish tries to prevent the engine from
simplifying the position too quickly when it feels that it is very
slightly behind, instead keeping the tension a little bit longer.

Various tests in November 2017 have proved that our current imple-
mentation works well against SF7 (which is about 130 Elo weaker than
current master) and than the Elo gain is an increasing function of
contempt, going (against SF7) from +0 Elo when contempt is set at
zero centipawns, to +30 Elo when contempt is 40 centipawns.

See pull request 1325 for details:

https://github.com/official-stockfish/Stockfish/pull/1325

This november discussion left open the decision of which "default"
value for contempt we should use for Stockfish, taking into account
the various uses ofStockfish (opening preparation for humans, computer
online tournaments,analysis tool for web pages, human/computer play,
etc).

This pull request proposes to set the default contempt value of SF
to twenty centipawns, which turns out to be the highest value which
is not a regression against current master, as this seemed to be a
good compromise between risk and safety. A couple of SPRT[-3..1]
tests were done to bisect this value:

Contempt 10: http://tests.stockfishchess.org/tests/view/5a5d42d20ebc5902977e2901 (PASSED)
Contempt 15: http://tests.stockfishchess.org/tests/view/5a5d41740ebc5902977e28fa (PASSED)
Contempt 20: http://tests.stockfishchess.org/tests/view/5a5d42060ebc5902977e28fc (PASSED)
Contempt 25: http://tests.stockfishchess.org/tests/view/5a5d433f0ebc5902977e2904 (FAILED)

Surprisingly, a test at "very long time control" hinted that using
contempt 20 is not only be non-regressive against contempt 0, but
may actually exhibit some small Elo gain, giving a likehood of superio-
rity of 88.7% after 8500 games:

VLTC:
ELO: 2.28 +-3.7 (95%) LOS: 88.7%
Total: 8521 W: 1096 L: 1040 D: 6385
http://tests.stockfishchess.org/tests/view/5a60b2820ebc590297b9b7e0

Finally, there was some concerns that a contempt value of 20 would
be worse than a value of 7, but a test with 20000 games at STC was
neutral:

STC:
ELO: 0.45 +-3.1 (95%) LOS: 61.2%
Total: 20000 W: 4222 L: 4196 D: 11582
http://tests.stockfishchess.org/tests/view/5a64d2fd0ebc590297903868

See the comments in pull request 1361 for the long, nice discussion
(180 entries :-)) leading to the decision to propose contempt 20 as
the default value:

https://github.com/official-stockfish/Stockfish/pull/1361

Whether Stockfish should strictly adhere to the Komodo and Houdini
semantics and add the UCI commands to force the contempt to be White
in the so-called "analysis mode" is still under discussion, and may
be or may not be the object of a future commit.

Bench: 5783344
2018-01-23 14:26:45 +01:00

164 lines
5.1 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) 2015-2018 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
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/>.
*/
#include <algorithm>
#include <cassert>
#include <ostream>
#include "misc.h"
#include "search.h"
#include "thread.h"
#include "tt.h"
#include "uci.h"
#include "syzygy/tbprobe.h"
using std::string;
UCI::OptionsMap Options; // Global object
namespace UCI {
/// 'On change' actions, triggered by an option's value change
void on_clear_hash(const Option&) { Search::clear(); }
void on_hash_size(const Option& o) { TT.resize(o); }
void on_logger(const Option& o) { start_logger(o); }
void on_threads(const Option& o) { Threads.set(o); }
void on_tb_path(const Option& o) { Tablebases::init(o); }
/// Our case insensitive less() function as required by UCI protocol
bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const {
return std::lexicographical_compare(s1.begin(), s1.end(), s2.begin(), s2.end(),
[](char c1, char c2) { return tolower(c1) < tolower(c2); });
}
/// init() initializes the UCI options to their hard-coded default values
void init(OptionsMap& o) {
// at most 2^32 clusters.
const int MaxHashMB = Is64Bit ? 131072 : 2048;
o["Debug Log File"] << Option("", on_logger);
o["Contempt"] << Option(20, -100, 100);
o["Threads"] << Option(1, 1, 512, on_threads);
o["Hash"] << Option(16, 1, MaxHashMB, on_hash_size);
o["Clear Hash"] << Option(on_clear_hash);
o["Ponder"] << Option(false);
o["MultiPV"] << Option(1, 1, 500);
o["Skill Level"] << Option(20, 0, 20);
o["Move Overhead"] << Option(30, 0, 5000);
o["Minimum Thinking Time"] << Option(20, 0, 5000);
o["Slow Mover"] << Option(89, 10, 1000);
o["nodestime"] << Option(0, 0, 10000);
o["UCI_Chess960"] << Option(false);
o["SyzygyPath"] << Option("<empty>", on_tb_path);
o["SyzygyProbeDepth"] << Option(1, 1, 100);
o["Syzygy50MoveRule"] << Option(true);
o["SyzygyProbeLimit"] << Option(6, 0, 6);
}
/// operator<<() is used to print all the options default values in chronological
/// insertion order (the idx field) and in the format defined by the UCI protocol.
std::ostream& operator<<(std::ostream& os, const OptionsMap& om) {
for (size_t idx = 0; idx < om.size(); ++idx)
for (const auto& it : om)
if (it.second.idx == idx)
{
const Option& o = it.second;
os << "\noption name " << it.first << " type " << o.type;
if (o.type != "button")
os << " default " << o.defaultValue;
if (o.type == "spin")
os << " min " << o.min << " max " << o.max;
break;
}
return os;
}
/// Option class constructors and conversion operators
Option::Option(const char* v, OnChange f) : type("string"), min(0), max(0), on_change(f)
{ defaultValue = currentValue = v; }
Option::Option(bool v, OnChange f) : type("check"), min(0), max(0), on_change(f)
{ defaultValue = currentValue = (v ? "true" : "false"); }
Option::Option(OnChange f) : type("button"), min(0), max(0), on_change(f)
{}
Option::Option(int v, int minv, int maxv, OnChange f) : type("spin"), min(minv), max(maxv), on_change(f)
{ defaultValue = currentValue = std::to_string(v); }
Option::operator int() const {
assert(type == "check" || type == "spin");
return (type == "spin" ? stoi(currentValue) : currentValue == "true");
}
Option::operator std::string() const {
assert(type == "string");
return currentValue;
}
/// operator<<() inits options and assigns idx in the correct printing order
void Option::operator<<(const Option& o) {
static size_t insert_order = 0;
*this = o;
idx = insert_order++;
}
/// operator=() updates currentValue and triggers on_change() action. It's up to
/// the GUI to check for option's limits, but we could receive the new value from
/// the user by console window, so let's check the bounds anyway.
Option& Option::operator=(const string& v) {
assert(!type.empty());
if ( (type != "button" && v.empty())
|| (type == "check" && v != "true" && v != "false")
|| (type == "spin" && (stoi(v) < min || stoi(v) > max)))
return *this;
if (type != "button")
currentValue = v;
if (on_change)
on_change(*this);
return *this;
}
} // namespace UCI