3.9.1 Some basic options ¶

• --help, -h

  Print a help message describing the options. This will also tell you the defaults of various parameters, most importantly the level and cache size. The default values of these parameters can be set before compiling by configure. If you forget the defaults you can find out using --help.

• --boardsize size

  Set the board size

• --komi num

  Set the komi

• --level level

  GNU Go can play with different strengths and speeds. Level 10 is the default. Decreasing the level will make GNU Go faster but less accurate in its reading.

• --quiet, --silent

  Don’t print copyright and other messages. Messages specifically requested by other command line options, such as --trace, are not supressed.

• -l, --infile filename

  Load the named SGF file. GNU Go will generate a move for the player who is about to move. If you want to override this and generate a move for the other player you may add the option --color <color> where <color> is black or white.

• -L, --until move

  Stop loading just before the indicated move is played. move can be either the move number or location.

• -o, --outfile filename

  Write sgf output to file

• -O, --output-flags flags

  Add useful information to the sgf file. Flags can be ’d’, ’v’ or both (i.e. ’dv’). If ’d’ is specified, dead and critical dragons are marked in the sgf file. If ’v’ is specified, move valuations around the board are indicated.

• --mode mode

  Force the playing mode (’ascii’, ’emacs,’ ’gmp’ or ’gtp’). The default is ASCII, but if no terminal is detected GMP (Go Modem Protocol) will be assumed. In practice this is usually what you want, so you may never need this option.

• --resign-allowed

  GNU Go will resign games if this option is enabled. This is the default unless you build the engine with the configure option --disable-resignation-allowed. Unfortunately the Go Modem Protocol has no provision for passing a resignation, so this option has no effect in GMP mode.

• --never-resign

  GNU Go will not resign games.

• --resign-allowed

  GNU Go will resign lost games. This is the default.

3.9.2 Monte Carlo Options ¶

GNU Go can play Monte Carlo Go on a 9x9 board. (Not available for larger boards.) It makes quite a strong engine. Here are the command line options.

• --monte-carlo

  Use Monte Carlo move generation (9x9 or smaller).

• --mc-games-per-level <number>

  Number of Monte Carlo simulations per level. Default 8000. Thus at level 10, GNU Go simulates 80,000 games in order to generate a move.

• --mc-list-patterns

  list names of builtin Monte Carlo patterns

• --mc-patterns <name>

  Choose a built in Monte Carlo pattern database. The argument can be mc_mogo_classic, mc_montegnu_classic or mc_uniform.

• --mc-load-patterns <filename>

  read Monte Carlo patterns from file

3.9.3 Other general options ¶

• -M, --cache-size megs

  Memory in megabytes used for caching of read results. The default size is 8 unless you configure gnugo with the command configure --enable-cache-size=size before compiling to make size the default (see Installation). GNU Go stores results of its reading calculations in a hash table (see Hashing of Positions). If the hash table is filled, it is emptied and the reading continues, but some reading may have to be repeated that was done earlier, so a larger cache size will make GNU Go run faster, provided the cache is not so large that swapping occurs. Swapping may be detected on GNU/Linux machines using the program top. However, if you have ample memory or if performance seems to be a problem you may want to increase the size of the cache using this option.

• --chinese-rules

  Use Chinese rules. This means that the Chinese or Area Counting is followed. It may affect the score of the game by one point in even games, more if there is a handicap (since in Chinese Counting the handicap stones count for Black) or if either player passes during the game.

• --japanese-rules

  Use Japanese Rules. This is the default unless you specify --enable-chinese-rules as a configure option.

• --play-out-aftermath
• --capture-all-dead

  These options cause GNU Go to play out moves that are usually left unplayed after the end of the game. Such moves lose points under Japanese rules but not Chinese rules. With --play-out-aftermath, GNU Go may play inside its territory in order to reach a position where it considers every group demonstrably alive or dead. The option --capture-all-dead causes GNU Go to play inside its own territory to remove dead stones.

• --forbid-suicide

  Do not allow suicide moves (playing a stone so that it ends up without liberties and is therefore immediately removed). This is the default.

• --allow-suicide

  Allow suicide moves, except single-stone suicide. The latter would not change the board at all and pass should be used instead.

• --allow-all-suicide

  Allow suicide moves, including single-stone suicide. This is only interesting in exceptional cases. Normally the --allow-suicide option should be used instead.

• --simple-ko

  Do not allow an immediate recapture of a ko so that the previous position is recreated. Repetition of earlier positions than that are allowed. This is default.

• --no-ko

  Allow all kinds of board repetition.

• --positional-superko

  Forbid repetition of any earlier board position. This only applies to moves on the board; passing is always allowed.

• --situational-superko

  Forbid repetition of any earlier board position with the same player to move. This only applies to moves on the board; passing is always allowed.

• --copyright: Display the copyright notice
• --version or -v: Print the version number
• --printsgf filename:

  Create an SGF file containing a diagram of the board. Useful with -l and -L to create a diagram of the board from another sgf file. Illegal moves are indicated with the private IL property. This property is not used in the FF4 SGF specification, so we are free to preempt it.

• --options

  Print which experimental configure options were compiled into the program (see Other Options).

• --orientation n

  Combine with -l. The Go board can be oriented in 8 different ways, counting reflections and rotations of the position; this option selects an orientation (default 0). The parameter ‘n’ is an integer between 0 and 7.

3.9.4 Other options affecting strength and speed ¶

• --level amount

  The higher the level, the deeper GNU Go reads. Level 10 is the default. If GNU Go plays too slowly on your machine, you may want to decrease it.

This single parameter --level is the best way of choosing whether to play stronger or faster. It controls a host of other parameters which may themselves be set individually at the command line. The default values of these parameters may be found by running gnugo --help.

Unless you are working on the program you probably don’t need the remaining options in this category. Instead, just adjust the single variable --level. The following options are of use to developers tuning the program for performance and accuracy. For completeness, here they are.

• -D, --depth depth

  Deep reading cutoff. When reading beyond this depth (default 16) GNU Go assumes that any string which can obtain 3 liberties is alive. Thus GNU Go can read ladders to an arbitrary depth, but will miss other types of capturing moves.

• -B, --backfill-depth depth

  Deep reading cutoff. Beyond this depth (default 12) GNU Go will no longer try backfilling moves in its reading.

• --backfill2-depth depth

  Another depth controlling how deeply GNU Go looks for backfilling moves. The moves tried below backfill2_depth are generally more obscure and time intensive than those controlled by backfill_depth, so this parameter has a lower default.

• -F, --fourlib-depth depth

  Deep reading cutoff. When reading beyond this depth (default 7) GNU Go assumes that any string which can obtain 4 liberties is alive.

• -K, --ko-depth depth

  Deep reading cutoff. Beyond this depth (default 8) GNU Go no longer tries very hard to analyze kos.

• --branch-depth depth

  This sets the branch_depth, typically a little below the depth. Between branch_depth and depth, attacks on strings with 3 liberties are considered but branching is inhibited, so fewer variations are considered. Below this depth (default 13), GNU Go still tries to attack strings with only 3 liberties, but only tries one move at each node.

• --break-chain-depth depth

  Set the break_chain_depth. Beyond this depth, GNU Go abandons some attempts to defend groups by trying to capture part of the surrounding chain.

• --aa-depth depth

  The reading function atari_atari looks for combinations beginning with a series of ataris, and culminating with some string having an unexpected change in status (e.g. alive to dead or critical). This command line optio sets the parameter aa_depth which determines how deeply this function looks for combinations.

• --superstring-depth

  A superstring (see Superstrings) is an amalgamation of tightly strings. Sometimes the best way to attack or defend a string is by attacking or defending an element of the superstring. Such tactics are tried below superstring_depth and this command line option allows this parameter to be set.

The preceeding options are documented with the reading code (see Reading Basics).

• --owl-branch Below this depth Owl only considers one move. Default 8.
• --owl-reading Below this depth Owl assumes the dragon has escaped. Default 20.
• --owl-node-limit

  If the number of variations exceeds this limit, Owl assumes the dragon can make life. Default 1000. We caution the user that increasing owl_node_limit does not necessarily increase the strength of the program.

• --owl-node-limit n

  If the number of variations exceeds this limit, Owl assumes the dragon can make life. Default 1000. We caution the user that increasing owl_node_limit does not necessarily increase the strength of the program.

• --owl-distrust n

  Below this limit some owl reading is truncated.

3.9.5 Ascii mode options ¶

• --color color

  Choose your color (’black’ or ’white’).

• --handicap number

  Choose the number of handicap stones (0–9)

For more information about the following clock options see See Ascii Interface.

• --clock seconds

  Initialize the timer.

• --byo-time seconds

  Number of seconds per (Canadian) byo-yomi period

• --byo-period stones

  Number of stones per (Canadian) byo-yomi period

3.9.6 Development options ¶

• --replay color

  Replay all moves in a game for either or both colors. If used with the -o option the game record is annotated with move values. This option requires -l filename. The color can be:

  • white: replay white moves only
  • black: replay black moves only
  • both: replay all moves

  When the move found by genmove differs from the move in the sgf file the values of both moves are reported thus:

  Move 13 (white): GNU Go plays C6 (20.60) - Game move F4 (20.60) 
  

  This option is useful if one wants to confirm that a change such as a speedup or other optimization has not affected the behavior of the engine. Note that when several moves have the same top value (or nearly equal) the move generated is not deterministic (though it can be made deterministic by starting with the same random seed). Thus a few deviations from the move in the sgf file are to be expected. Only if the two reported values differ should we conclude that the engine plays differently from the engine which generated the sgf file. See Regression testing.

• -a, --allpats

  Test all patterns, even those smaller in value than the largest move found so far. This should never affect GNU Go’s final move, and it will make it run slower. However this can be very useful when "tuning" GNU Go. It causes both the traces and the output file (-o) to be more informative.

• -T, --printboard: colored display of dragons.

  Use rxvt, xterm or Linux Console. (see Colored Display)

• --showtime

  Print timing information to stderr.

• -E, --printeyes: colored display of eye spaces

  Use rxvt, xterm or Linux Console. (see Colored Display)

• -d, --debug level

  Produce debugging output. The debug level is given in hexadecimal, using the bits defined in the following table from engine/gnugo.h. A list of these may be produced using --debug-flags. Here they are in hexadecimal:

    DEBUG_INFLUENCE             0x0001
    DEBUG_EYES                  0x0002
    DEBUG_OWL                   0x0004
    DEBUG_ESCAPE                0x0008
    DEBUG_MATCHER               0x0010
    DEBUG_DRAGONS               0x0020
    DEBUG_SEMEAI                0x0040
    DEBUG_LOADSGF               0x0080
    DEBUG_HELPER                0x0100
    DEBUG_READING               0x0200
    DEBUG_WORMS                 0x0400
    DEBUG_MOVE_REASONS          0x0800
    DEBUG_OWL_PERFORMANCE       0x1000
    DEBUG_LIFE                  0x2000
    DEBUG_FILLLIB               0x4000
    DEBUG_READING_PERFORMANCE   0x8000
    DEBUG_SCORING               0x010000
    DEBUG_AFTERMATH             0x020000
    DEBUG_ATARI_ATARI           0x040000
    DEBUG_READING_CACHE         0x080000
    DEBUG_TERRITORY             0x100000
    DEBUG_OWL_PERSISTENT_CACHE  0X200000
    DEBUG_TOP_MOVES             0x400000
    DEBUG_MISCELLANEOUS         0x800000
    DEBUG_ORACLE_STREAM         0x1000000
  

  These debug flags are additive. If you want to turn on both dragon and worm debugging you can use -d0x420.

• --debug-flags

  Print the list of debug flags

• -w, --worms

  Print more information about worm data.

• -m, --moyo level

  moyo debugging, show moyo board. The level is fully documented elsewhere (see Colored display and debugging of influence).

• -b, --benchmark number

  benchmarking mode - can be used with -l. Causes GNU Go to play itself repeatedly, seeding the start of the game with a few random moves. This method of testing the program is largely superceded by use of the twogtp program.

• -S, --statistics

  Print statistics (for debugging purposes).

• -t, --trace

  Print debugging information. Use twice for more detail.

• -r, --seed seed

  Set random number seed. This can be used to guarantee that GNU Go will make the same decisions on multiple runs through the same game. If seed is zero, GNU Go will play a different game each time.

• --decide-string location

  Invoke the tactical reading code (see Tactical reading to decide whether the string at location can be captured, and if so, whether it can be defended. If used with -o, this will produce a variation tree in SGF.

• --decide-owl location

  Invoke the owl code (see The Owl Code) to decide whether the dragon at location can be captured, and whether it can be defended. If used with -o, this will produce a variation tree in SGF.

• --decide-connection location1/location2

  Decide whether dragons at location1 and location2 can be connected. Useful in connection with -o to write the variations to an SGF file.

• --decide-dragon-data location

  Print complete information about the status of the dragon at location.

• --decide-semeai location1/location2

  At location1 and location2 are adjacent dragons of the opposite color. Neither is aliveby itself, and their fate (alive, dead or seki) depends on the outcome of a semeai (capturing race). Decide what happens. Useful in connection with -o to write the variations to an SGF file.

• --decide-tactical-semeai location1/location2

  Similar to --decide-semeai, except that moves proposed by the owl code are not considered.

• --decide-position

  Try to attack and defend every dragon with dragon.escape<6. If used with -o, writes the variations to an sgf file.

• --decide-eye location

  Evaluates the eyespace at location and prints a report. You can get more information by adding -d0x02 to the command line. (see Eye Local Game Values.)

• --decide-surrounded location

  A dragon is surrounded if it is contained in the convex hull of its unfriendly neighbor dragons. This does not mean that it cannot escape, but it is often a good indicator that the dragon is under attack. This option draws the convex hull of the neighbor dragons and decides whether the dragon at location is surrounded.

• --decide-combination

  Calls the function atari_atari to decide whether there exist combinations on the board.

• --score method

  Requires -l to specify which game to score and -L if you want to score anywhere else than at the end of the game record. method can be "estimate", "finish", or "aftermath". "finish" and "aftermath" are appropriate when the game is complete, or nearly so, and both try to supply an accurate final score. Notice that if the game is not already finished it will be played out, which may take quite a long time if the game is far from complete. The "estimate" method may be used to get a quick estimate during the middle of the game. Any of these options may be combined with --chinese-rules if you want to use Chinese (Area) counting.

  If the option -o outputfilename is provided, the result will also be written as a comment in the output file. For the "finish" and "aftermath" scoring algorithms, the selfplayed moves completing the game are also stored.

  • finish

    Finish the game by selfplaying until two passes, then determine the status of all stones and compute territory.

  • aftermath

    Finish the game by selfplaying until two passes, then accurately determine status of all stones by playing out the "aftermath", i.e. playing on until all stones except ones involved in seki have become either unconditionally (in the strongest sense) alive or unconditionally dead (or captured). Slower than --score finish, and while these algorithms usually agree, if they differ, --score aftermath is most likely to be correct.

• --score aftermath --capture-all-dead --chinese-rules

  This combination mandates Tromp-Taylor scoring. The Tromp-Taylor ruleset requires the game to be played out until all dead stones are removed, then uses area (Chinese) scoring. The option --capture-all-dead requires the aftermath code to finish capturing all dead stones.

3.9.7 Experimental options ¶

Most of these are available as configure options and are described in Other Options.

• --options

  Print which experimental configure options were compiled into the program.

• --with-break-in
• --without-break-in

  Use or do not use the experimental break-in code. This option has no effect at level 9 or below. The break in code is enabled by default at level 10, and the only difference between levels 9 and level 10 is that the break in code is disabled at level 9.

• --cosmic-gnugo

  Use center oriented influence.

• --nofusekidb

  Turn off the fuseki database.

• --nofuseki

  Turn off fuseki moves entirely

• --nojosekidb

  Turn off the joseki database.

• --mirror

  Try to play mirror go.

• --mirror-limit n

  Stop mirroring when n stones are on the board.