Small Potato (aka unches)

An attempt at a chess program. Sitting at around 1900 on 3-minute chess on FICS (nick is unches).

Features

• Good compatibility with the Chess Engine Communication Protocol.
• Runtime definable value tables
• Negascout/Alpha-beta/transposition table/quiescent search/null-move pruning/history move ordering
• Lots of bugs for your debugging exercises

Download it here (sourceforge). GPL license. Latest version is 0.6.1

The opening book is packaged separately since it is relatively big (3 MB compressed). This should be put in the same directory as smallpotato. There has been no changes in book format yet, so any book from old releases should work just as well. Windows binaries are also available for most releases

More info at the project page on sourceforge

Release notables:

25/09/03 - 0.6.1

• Tweaked move ordering (including addition of killer move heuristic)
• Minor tweaking of evaluation (with unknown consequences)
• More configurable settings
• Removed MTD(f) and standard alpha-beta search as search options
• Bugfixes (including K v K draw claim)

17/09/02 - 0.6.0

• Added null-move pruning and aspiration window.
• Improved endgame evaluation (or, more precisely, it now has a separate endgame evaluation). Same with king execution phase.
• Now claims draw on insufficient material.
• Slightly friendlier command line mode.
• Minor bugfixes (fen/epd parsing).

18/08/02 - 0.5.1

• Now can be configured through file.
• It can now resign.
• Switched, and very slightly tweaked, default evaluation function.
• Speeded up by about 20%.

03/08/02 - 0.5.0

• Switched default search algorithm to negascout
• Now recover a PV line for display
• Minor transposition table tweaking
• Minor fixes of bugs introduced in 0.4.0
• Now compiles out-of-the-box in clig-less systems.

17/07/02 - 0.4.0

• Implemented move now and analyze.
• Switched to 0x88 move generation.

11/04/02 - 0.3.3

• Added opening book.
• EPD suites and lines can be solved
• Made it portable to cygwin
• Changed default hashtable size to 32MB.
• Can now specify hashtable size in kilobytes.
• Made aleweights.out be loaded by default

03/04/02 - 0.3.2

• No changes (reflex action release that shouldn't have
• happened due to unkown last release)

08/03/02 - 0.3.1

• Changed to delayed checking of check for speculated performance
• improvement (even though it does not seem to have materialised)
• Got rid of a couple of often used functions with array lookups for definite
• performance gains.
• Completed switch to move/unmove.

26/02/02 - 0.3.0

• Changed name to Small Potato
• Changed to move/unmove instead of move/copy struct (faster)
• Implemented undo and remove for xboard/protocol 2 programs
• (Note: Search instability noted in previous version is "meant" to be there.
• Caused by the nature of transposition tables, not by some bug in implementation)
• No bugfixes

07/11/01 - 0.2.4

• Better randomised play
• Switched to 64-bit random hashes
• Lots of bugfixes, including the crash on start
• introduced in v0.2.3, PGN output bugfixes, and
• some silliness in QuiescentSearch.
• (NOTE: Search instability still there)

20/10/01 - 0.2.3

• Added history ordering
• Better time management.
• PGN output for game recording.
• Bugfixes

13/10/01 - 0.2.2

• Changed GPL license
• Added quiescent search
• Bugfixes

09/10/01 - 0.2.1

• Added internal iterative deepening
• Bugfixes

03/10/01 - 0.2.0

• Switched to MTD(f)
• Bugfixes

01/10/01 - 0.1.5

• Bit of documentation.
• Fixed the hashtable (maybe)

01/10/01 - 0.1.4

• Improved packaging.
• Couple of bugfixes.

16/04/01 - 0.1.3

• Switched to Zobrist hashing.
• Switched to negamax
• Added runtime evaluation board loading
• Lots of bugfixes (especially hashtable)

14/03/01 - 0.1.2

• Added hashtable.
• Lots of bugfixes.

14/02/01 - 0.1.1

• Added first move move ordering.
• Improved FICS automation.
• Better logging and recording
• Lots of bugfixes

25/12/00 - 0.1.0

• Initial release

Comments, bugs, flames and code are encouraged, should be sent to alito@organicrobot.com