Kiwi
Copyright (c) 1999-2004,2005 by Alessandro Scotti.
http://www.ascotti.org/
Kiwi is a Winboard/XBoard
chess engine.
Version 0.4d
Feb 08, 2005. Very little changes from version 0.4c, mainly on
extensions and move ordering at the root (I am always experimenting on
this and I hope I've got it right this time, it's more a matter of
principles than else...). There is an important bug fix though, as
under Linux the engine was "stealing" some CPU time from the opponent.
Version 0.4c
Jan 30, 2005. Most of the search and move ordering code has been
rewritten to make things simpler. SEE is back in, used for ordering and
pruning. Several bugs have been fixed, including those slipped in
version 0.4a... All in all this version should be stronger than 0.4b,
but most important it will make future work much easier.
Version 0.4b
Jan 16, 2005. Ops! A major bug (...ok, make that a couple...) slipped
in previous version so a lot of code in this version had to be
recovered from version 0.3c... my fault for not testing the new code
carefully enough! :-( Now there will be no more extra features for a
while,
as current code needs some cleaning and polishing first...
Version 0.4a
Jan 09, 2005. Finally added a SEE, which is currently used to prune
quiesce captures. Tentative implementation of a history-based pruning.
Book loading is about 4x faster, thanks to improved parsing of
SAN moves. Some tweaks and bug fixes.
Version 0.3c
Nov 29, 2004. Many bug fixes in the evaluation code. Some changes in
move ordering, pruning, extensions and quiesce search
should make the engine more aware of tactical shots. Of course pumping
up search parameters is not without risks in
itself, so we'll have to wait some games to see if it really works in
practice...
Version 0.3b
Nov 17, 2004. After a long struggle, I've had to wave goodbye to my
beloved multithreaded input code: it's just too unreliable under
Windows. The system library now detects when standard input is a pipe
(i.e. engine is being run under Winboard, Arena or so) and if so uses
polling. Other platforms and input types (e.g. console) keep using the
"old" approach. I've also fixed two nasty bugs in the pondering code...
very difficult to find! Many thanks to Günther Simon (RWBC tournament) and Leo
Dijksman (WBEC-Ridderkerk
tournament) for sending the bug info and helping me testing the
fix! :-)
Version 0.3a
Nov 12, 2004. Some engine parameters can be specified in a
configuration
file (see instructions inside "kiwi.ini")... more configurable
parameters to come! Fixed a bug in en-passant handling, which
unfortunately makes old books incompatible. Evaluation stuff has been
completely rewritten. This doesn't necessarily mean that Kiwi plays
better right now, because 1) it still lacks a lot of knowledge; 2) it
runs slower; 3) there are literally hundreds of parameters that
must be tuned and that could take a long time! In the long run,
however, the new design should make for better chess.
Version 0.2b
Oct 8, 2004. Linux binaries. Book manager now trims some unwanted
transpositions. After the sequence 1. e3 e4 2. e5 Nf6 3. Nf3 Kiwi would
play Ng8?? out of book! Suite command works properly.
Version 0.2a
Oct 6, 2004. Fixed a bug in time control handling where the engine
would not consider the moves played manually. Some minor fixes. Added
opening book (simple stuff really, but it works).
How to create an opening book.
Run the engine in console mode and type "help": a short help screen
should appear. You can use the "bookadd" command to add positions to an
internal book (different from that used to play), it takes three
parameters: the name of the file containing the games in PGN format,
the minimum number of moves for a game to be considered, and how many
plies (half moves) have to be copied in the book. So for example:
bookadd gm2600.pgn 30 20
loads games that last at least 30 moves from file "gm2600.pgn", and
copies the first 20 plies (10 full moves) into the book. Note that
subsequent "bookadd" commands will add positions to the internal book,
so it can only grow in size. The only way to reset it is to exit from
the program.
Note: during book creation, the entire internal book is kept in RAM so
there is probably a limit to the number of games it is possible to
load. I've only tested it with about 70000 games (a few million
positions) so do not exaggerate!
After the internal book has been populated, you can save it with the
"booksave" command, for example:
booksave book4.dat 4
will create an opening book named "book4.dat" that contains all
positions that were played at least 4 times. It is possible to save as
many books as wished without having to reload the games in between.
At startup Kiwi automatically loads a book named "kiwi.obk" (if found).
In console mode, you can load any other book with the "bookload"
command followed by the book filename.
How to run a test suite. In
console mode, run the "suite" command specifying the name of an EPD
file containing test positions and how many seconds per move to think.
At present only "bm" (best move) tags are supported (i.e. no "avoid"
moves). For example:
suite wacnew.epd 5
All results are put in the log file "kiwi_log.txt".
How to run perft. In console
mode, simply issue the command "perft" followed by the desired depth.
The test is run from the current position, which can be changed by
"setboard" followed by a valid FEN string.
Tip: filenames containing
spaces
may be quoted.
Tip: it's possible to see what
the book suggests using Winboard. Click on Help -> Book. In console
mode, this corresponds to the command "bk". Note that all suggestions
come from the last loaded book, the internal book is used only for
creating other books and never for playing.
Tip: Winboard commands are
always valid. So, type "quit" to exit from the program.
Version 0.1c
Sep 30, 2004. Just a bug fix for Win95/98 users: program would freeze
at startup.
Version 0.1b
Sep 19, 2004. First public release. Supports most of the Winboard
protocol. No
opening book yet. No configuration file. Logging always enabled, will
log info on "kiwi_log.txt": this file is overwritten every time the
engine starts.
History
Development on the Kiwi engine began in December 1999 but stopped
almost completely in January 2000. At the time I was also working on a
GUI written in Delphi, which I also had to abandon for reasons that I
can't remember now (though, statistically speaking, "too much work at
real job" shouldn't be too far from truth). Last August (2004) I was
stuck for technical reasons on my latest project Tickle
and decided to
wipe some dust from good ol' Kiwi. The newest build I could find in my
disk was from March 2000, which contained at least a few fixes with
respect to the January build, which was really buggy.
Most of the work I did during August and September 2004 was fixing the
bugs left (sometimes with help from the great folks at CCC) and implementing the
Winboard protocol. In fact, the engine is lacking some serious work in
important areas (e.g. how positions are evaluated), but for now playing
weak chess is a great improvement with respect to playing illegal
chess! :-)
Technical data
Kiwi's development was heavily influenced by Prof. Hyatt's engine
Crafty (I think it was
version 9.x at the time!), so I'm also using
bitboards, rotated bitboards and similar code for move generation and
move ordering. However, Kiwi is written in C++ and the design and
implementation is quite different from Crafty's. Besides, there are
several things I want to do differently now, but they'll have to wait
for some future release.
For searching, I'm using the MTD(f) algorithm as described by Aske
Plaat, and I've had my share of trouble getting it to work reliably
enough. The rest is pretty much standard stuff: futility pruning,
null-move (R=1), check and pawn push extensions, 2-slot per entry hash
table. I have a long "todo" list though, and many things are definitely
going to change...
WAC (new) results: 285/300 on 700 MHz Athlon at 5 seconds per move,
297/300 on 1.8 GHz P4 at 30 seconds per move. Kiwi nemesis: WAC 180.
System requirements
For Windows: any 32-bit version
of Windows, running on a Athlon or Pentium 3 CPU or better. Couldn't
test it on many platforms though. Engine requires about 3 Mb of free
RAM plus the space allocated for hash tables (configurable from version
3.0a).
For Linux: same as Windows, but running Linux! :-)
License
Kiwi is Copyright (c) 1999-2004,2005 by Alessandro Scotti.
This program is distributed "as-is"
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. In no event will the author be held liable for any damage
arising from the use of this software.