4739037f96
This gives SF accurate PVs, such that the evaluation of the leaf node in the PV matches the score backed up to the root (99% of the time. q-search will use the value stored in the hash table instead of the eval value sometimes). One drawback is that fail-high/low only get a minimal 2 move PV. It doesn't add any additional overhead to the non-PV codepath except an extra eight bytes to the SearchStack structure in multi-threaded searches. A core part of this is not pruning based on TT score in PV nodes. This was measured as not being a regression at multiple TCs, except for one exception, fast TC with huge hash, which is not realistic for longer searches. STC - 1 thread, 128 mb hash ELO: 1.42 +-3.1 (95%) LOS: 81.9% Total: 20000 W: 4078 L: 3996 D: 11926 STC - 3 thread, 128 mb hash ELO: -3.60 +-2.9 (95%) LOS: 0.8% Total: 20000 W: 3575 L: 3782 D: 12643 STC - 3 thread, 8 mb hash ELO: 0.12 +-2.9 (95%) LOS: 53.3% Total: 20000 W: 3654 L: 3647 D: 12699 LTC - 3 thread, 32mb hash ELO: 2.29 +-2.0 (95%) LOS: 98.8% Total: 35740 W: 5618 L: 5382 D: 24740 Bench: 6984058 Resolves #102 |
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| src | ||
| AUTHORS | ||
| Copying.txt | ||
| Readme.md | ||
Overview
Stockfish is a free UCI chess engine derived from Glaurung 2.1. It is not a complete chess program and requires some UCI-compatible GUI (e.g. XBoard with PolyGlot, eboard, Arena, Sigma Chess, Shredder, Chess Partner or Fritz) in order to be used comfortably. Read the documentation for your GUI of choice for information about how to use Stockfish with it.
This version of Stockfish supports up to 128 cores. The engine defaults to one search thread, so it is therefore recommended to inspect the value of the Threads UCI parameter, and to make sure it equals the number of CPU cores on your computer.
Files
This distribution of Stockfish consists of the following files:
-
Readme.md, the file you are currently reading.
-
Copying.txt, a text file containing the GNU General Public License.
-
src, a subdirectory containing the full source code, including a Makefile that can be used to compile Stockfish on Unix-like systems.
Compiling it yourself
On Unix-like systems, it should be possible to compile Stockfish directly from the source code with the included Makefile.
Stockfish has support for 32 or 64-bit CPUs, the hardware POPCNT instruction, big-endian machines such as Power PC, and other platforms.
In general it is recommended to run make help to see a list of make
targets with corresponding descriptions. When not using the Makefile to
compile (for instance with Microsoft MSVC) you need to manually
set/unset some switches in the compiler command line; see file types.h
for a quick reference.
Terms of use
Stockfish is free, and distributed under the GNU General Public License (GPL). Essentially, this means that you are free to do almost exactly what you want with the program, including distributing it among your friends, making it available for download from your web site, selling it (either by itself or as part of some bigger software package), or using it as the starting point for a software project of your own.
The only real limitation is that whenever you distribute Stockfish in some way, you must always include the full source code, or a pointer to where the source code can be found. If you make any changes to the source code, these changes must also be made available under the GPL.
For full details, read the copy of the GPL found in the file named Copying.txt