329 lines
13 KiB
Plaintext
329 lines
13 KiB
Plaintext
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1. Introduction
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---------------
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Glaurung is a free UCI chess engine. It is not a complete chess
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program, but requires some UCI compatible GUI (like XBoard with
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PolyGlot, eboard, Jos<6F>, Arena, Sigma Chess, Shredder, Chess Partner,
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or Fritz) in order to be used comfortably. Read the documentation for
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your GUI of choice for information about how to use Glaurung with your
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GUI.
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Glaurung 2 is a completely rewritten version of Glaurung. Apart from
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the parallel search code, almost no code is shared with Glaurung
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1.2.1, the previous stable version. The new program is clearly
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stronger than the old, but has a less attractive style of play,
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because there are still a few major holes in its evaluation function
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(most notably space and development).
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This version of Glaurung supports up to 8 CPUs, but has not been
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tested thoroughly with more than 2. The program tries to detect the
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number of CPUs on your computer and set the number of search threads
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accordingly, but please be aware that the detection is not always
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correct. It is therefore recommended to inspect the value of the
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"Threads" UCI parameter, and to make sure it equals the number of CPU
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cores on your computer.
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2. Files
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--------
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This distribution of Glaurung consists of the following files:
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* Readme.txt, the file you are currently reading.
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* Copying.txt, a text file containing the GNU General Public
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License.
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* src/, a subdirectory containing the full source code, including a
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Makefile that can be used to compile Glaurung on Unix-like
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systems. For further information about how to compile Glaurung
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yourself, read section 4 below.
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* MacOSX/, a subdirectory containing excutables for Apple Macintosh
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computers running Mac OS X 10.4 (Tiger) and newer. There are two
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executables, one for OS X 10.4, and one for OS X 10.5. The
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executable for OS X 10.4 will work in 10.5 as well, but the one
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for 10.5 is faster.
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* LinuxX86/, a subdirectory containing 32-bit and 64-bit x86 GNU/Linux
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executables.
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* Windows/, a subdirectory containing 32-bit and 64-bit Windows
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executables.
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* polyglot.ini, for using Glaurung with Fabien Letouzey's PolyGlot
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adapter.
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3. Opening books
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----------------
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This version of Glaurung has experimental support for PolyGlot opening
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books. For information about how to create such books, consult the
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PolyGlot documentation. The book file can be selected by setting the
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UCI parameter "Book File".
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A book file contributed by Salvo Spitaleri can be found on the
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Glaurung web page.
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4. Compiling it yourself
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------------------------
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On Unix-like systems, it should usually be possible to compile
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Glaurung directly from the source code with the included Makefile.
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The exception is computer with big-endian CPUs, like PowerPC
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Macintoshes. Some of the bitboard routines in the current version of
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Glaurung are endianness-sensitive, and won't work on a big-endian CPU.
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Ensuring that the line with #define USE_32BIT_ATTACKS" near the top
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of bitboard.h is commented out should solve this problem.
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Commenting out the line with "#define USE_32BIT_ATTACKS" near the
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There is also a problem with compiling Glaurung on certain 64-bit
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systems, regardless of the endianness. If Glaurung segfaults
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immediately after startup, try to comment out the line with
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"#define USE_FOLDED_BITSCAN" near the beginning of bitboard.h and
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recompile.
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Finally, even if Glaurung does work without any changes on your
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computer, it might be possible to improve the performance by changing
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some of the #define directives in bitboard.h. The default settings
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are optimized for 64-bit CPUs. On 32-bit CPUs, it is probably better
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to switch on USE_32BIT_ATTACKS, and to use BITCOUNT_SWAR_32 instead of
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BITCOUNT_SWAR_64. For computers with very little memory (like
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handheld devices), it is possible to conserve memory by defining
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USE_COMPACT_ROOK_ATTACKS.
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5. History
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----------
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2007-05-06: Glaurung 2 - epsilon
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--------------------------------
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The first public release, and the first version of my new program
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which is able to match the old Glaurung 1.2.1 on a single CPU. Lots
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of features and chess knowledge is still missing.
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2007-05-10: Glaurung 2 - epsilon/2
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----------------------------------
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This version is very close to 2 - epsilon. The major changes are:
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* A number of compatibility problems which appeared when trying to
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compile Glaurung 2 - epsilon on various operating systems and CPUs
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have been solved.
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* Fixed a major bug in the detection of rooks trapped inside a
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friendly king.
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* Added knowledge about several types of drawn endgames.
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* Fixed a few FRC related bugs. FRC now works, but because of
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serious holes in the evaluation function the program plays very
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badly.
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* A slightly more sophisticated king safety evaluation.
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2007-06-07: Glaurung 2 - epsilon/3
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----------------------------------
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The first public version with support for multiple CPUs. Unless you
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have a dual-core (or better) computer, use Glaurung with a PolyGlot
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book, or runs games with ponder on, you may want to skip this version,
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which is almost certainly no stronger than 2 - epsilon/2 when running
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on a single CPU. The main changes compared to the previous version
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are:
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* Parallel search, with support for 1-4 CPUs. The program currently
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always allocates a separate pawn hash table and material hash
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table for four threads, which is a pure waste of RAM if your
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computer has just a single CPU. This will be fixed in a future
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version.
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* Fixed a bug in book randomization. When using Polyglot books, the
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previous version would always select exactly the same move in the
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same position after a restart of the program. Thanks to Pavel
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H<>se for pointing this out.
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* Fixed a UCI pondering bug: Glaurung no longer instantly prints its
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best move when the maximum depth is reached during a ponder
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search, as the previous version did. According to the UCI
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protocol, it is not allowed to print the best move before the
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engine has received the "stop" or "quit" command.
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* Additional search information: The new version displays hash
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saturation and the current line(s) of search.
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* Several minor bug fixes and optimizations in the search and
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evaluation.
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2007-06-08: Glaurung 2 - epsilon/4
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----------------------------------
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A bugfix release, with only a single important change:
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* Fixed a very serious pondering bug. As pointed out by Marc
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Lacrosse, the previous version would lose on time in almost every
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single game with pondering enabled. The new version handles
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pondering correctly (or so I hope). When playing with ponder
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off, the new version is identical to version 2 - epsilon/3.
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2007-06-25: Glaurung 2 - epsilon/5
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----------------------------------
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Another minor update, including the following improvements and bug
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fixes:
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* As Werner Sch<63>le discovered, the previous version would sometimes
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stop thinking and lose on time right before delivering checkmate
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(which is of course a very unfortunate moment to lose on time).
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I haven't been able to reproduce Werner's problem on my computer
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(probably because I run a different OS), but I have fixed the bug
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which I suspect caused the time losses. I hope the time losses
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will no longer occur with 2 - epsilon/5.
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* The program is now slightly less resource-hungry on computers
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with less than 4 CPU cores: The previous version would always
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allocated separate pawn and material hash tables for four
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threads, even when running on a single-core CPU. The new version
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only allocates pawn and material hash tables for the threads
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which are actually used.
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* A minor reorganization of the memory layout has made the parallel
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search about 10% more efficient (at least on my computer, but the
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results are likely to vary considerably on different systems).
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* The Intel Mac OS X binary is much faster than before, thanks to
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the Intel C++ compiler (previous versions were compiled with
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GCC).
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* A few other very minor bug fixes and enhancements.
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2007-11-21: Glaurung 2.0
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------------------------
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The first stable (or so I hope) and feature-complete version of
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Glaurung 2. The following are the main changes compared to the
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previous version:
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* The license has been changed from GPL version 2 to GPL version 3.
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* MultiPV mode.
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* Support for the "searchmoves" option in the UCI "go" command.
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This means that it is possible to ask Glaurung to exclude some
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moves from its analysis, or to restrict its analysis to just a
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handful of moves selected by the user. This feature must also be
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supported by the GUI under which Glaurung is run. Glaurung's own
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GUI does currently not support this feature.
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* Chess960 support now works. The program still plays this game
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very badly, because of lack of opening knowledge.
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* Much more aggressive pruning in the last few plies of the main
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search.
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* Somewhat better scaling on multi-CPU systems, and support for up
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to 8 CPUs.
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* Lots of new UCI parameters.
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* Improved time managment, especially in games with pondering on
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(i.e. when the engine is allowed to think when it's the
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opponent's turn to move).
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* Some evaluation improvements, and some new basic endgame
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patterns.
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* The program should no longer crash if the game lasts longer than
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1000 plies.
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* Many minor bug fixes and other tiny improvements throughout the
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code.
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* More generously commented code, and numerous cosmetic changes in
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coding style.
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2007-11-22: Glaurung 2.0.1
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--------------------------
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* Fixed (or so I hope) a bug which would occasionally cause one of
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the search threads to get stuck forever in its idle loop.
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2008-05-14: Glaurung 2.1
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------------------------
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This version contains far too many changes to list them all, but most
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of them are minor and cosmetic. The most important and noticable
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changes are a lot of new UCI parameters, and many improvements in the
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evaluation function. The highlights are:
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* Extensive changes in the evaluation function. The addition of
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king safety is the most important improvement, but there are also
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numerous little improvements elsewhere in the evaluation. There
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is still much work left to do in the evaluation function, though.
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Space and development are still missing, and the tuning is likely
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to be very poor. Currently, the program is optimized for an
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entertaining style rather than maximum strength.
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* More accurate forward pruning. The previous version used the
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null move refutation move to improve the pruning accuracy by
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means of a very simple trick: It did not allow pruning of any
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moves with the piece captured by the null move refutation move.
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In Glaurung 2.1, this has been enhanced: It does not allow
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pruning of moves which defend the destination square of the null
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move refutation move, nor of moves which block the ray of the
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piece in the case that the moving piece in the null move
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refutation move is a slider.
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* More conservative use of LMR at PV nodes. The previous version
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searched the first 6 moves with full depth, 2.1 by default
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searches the first 14 moves with full depth (but there is a new
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UCI parameter for configuring this). I am not at all sure
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whether this is an improvement. More thorough testing is
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required.
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* Feedback from the evaluation to the search. The search passes an
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object of type 'EvalInfo' to the eval, and the eval fills this
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struct with various potentially useful information (like the sets
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of squares attacked by each piece type, the middle game and
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endgame components of the eval, etc.). At the moment, almost
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none of this information is actually used by the search. The
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only exception is that the evaluation function is now used to
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adjust the futility pruning margin in the quiescence search.
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* Less extensions. This hurts the programs performance a lot in most
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test suites, but I hope it improves the branching factor in deep
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searches.
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* A very long list of new UCI parameters, especially for tuning the
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evaluation.
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6. Terms of use
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---------------
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Glaurung is free, and distributed under the GNU General Public License
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(GPL). Essentially, this means that you are free to do almost exactly
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what you want with the program, including distributing it among your
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friends, making it available for download from your web site, selling
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it (either by itself or as part of some bigger software package), or
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using it as the starting point for a software project of your own.
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The only real limitation is that whenever you distribute Glaurung in
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some way, you must always include the full source code, or a pointer
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to where the source code can be found. If you make any changes to the
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source code, these changes must also be made available under the GPL.
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For full details, read the copy of the GPL found in the file named
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Copying.txt.
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7. Feedback
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-----------
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The author's e-mail address is tord@glaurungchess.com
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