EditBoard: resync Curses implementation with the Raw one.

[gnushogi.git] / doc / gnushogi.texi

\input texinfo   @c -*-texinfo-*-

@c % **  Start of header.
@setfilename gnushogi.info
@settitle GNU Shogi manual
@c % **  End of header.

@dircategory Games
@direntry
* gnushogi: (gnushogi).          Japanese chess
@end direntry

@setchapternewpage odd

@c ==================================
@c TeX-specific macros
@c ==================================

@c None yet!

@c ==================================
@c info-specific macros
@c ==================================

@c None yet!

@c ==================================
@c Summary description and copyright.
@c ==================================

@ifinfo

This file describes how to use GNU shogi, 
a program which plays Shogi (Japanese chess).

Copyright (C) 2013 Yann Dirson and the Free Software Foundation, Inc.
Copyright (C) 1999 Michael C. Vanier and the Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the Free Software Foundation.

@end ifinfo

@c =========================================
@c End of summary description and copyright.
@c =========================================


@c ====================
@c Title and copyright.
@c ====================

@titlepage
@sp 10
@comment The title is printed in a large font.
@center @titlefont{GNU Shogi (Japanese chess)}
@author   Mike Vanier

@c  The following two commands start the copyright page.
@page
@vskip 0pt plus 1filll
Copyright @copyright{} 2013-2014 Yann Dirson and the Free Software Foundation
Copyright @copyright{} 1999 Michael C. Vanier and the Free Software Foundation

@end titlepage

@c ===========================
@c End of title and copyright.
@c ===========================


@c =========================
@c Top node and master menu.
@c =========================

@node    Top, (dir), (dir), (dir)
@top     GNU Shogi (Japanese chess)

@ifnottex
@menu
* Introduction::         What is GNU shogi?
* About shogi::          General information, rules, etc.
* gnushogi::             How to play GNU shogi (gnushogi).
* References and links:: Where to go for more information.
* Acknowledgements::
* Bugs::                 Where and how to report bugs.
* Index::        
@end menu
@end ifnottex

@iftex
This document describes GNU shogi, a program which plays Japanese chess
(shogi) against a human opponent.
@end iftex

@c ================================
@c End of top node and master menu.
@c ================================


@c =====
@c Body.
@c =====

@node Introduction, About shogi, Top, Top
@chapter Introduction
@cindex Introduction

GNU shogi is a program that plays shogi, the Japanese version of chess,
against a human (or computer) opponent.  This file describes how to use
GNU shogi and also gives background information about the game of shogi.

This file describes GNU Shogi version 1.4.1, but most of it was
written for version 1.3.2 by Mike Vanier
@email{mvanier@@cs.caltech.edu}, maintainer of GNU shogi at that time.

GNU Shogi is currently maintained by Yann Dirson
@email{ydirson@@free.fr}.


GNU Shogi is actually one program, 'gnushogi', the text-based program
which also contains the game-playing engine.  By default it will play
Standard Shogi, but can be built to play Mini Shogi (with GNU Shogi
1.4.x, you will need to do that explicitely using `./configure
--enable-minishogi', but 1.5 will make this more straightforward).

Most players will just run GNU Shogi through one of the compatible
graphical interfaces:

@enumerate
@item
@uref{http://repo.or.cz/w/tagua/yd.git, Tagua}, a KDE-based GUI for
Chess and Shogi. Developement stopped several years ago, and it is
still somewhat maintained at Debian.  Probably the most sophisticated
and best-looking free GUI available today.

@item
@uref{https://alioth.debian.org/projects/omaha/, Omaha}, a generic
board-game GUI, supporting Shogi and other games, with currently only
a Gtk2-based UI.  Still under developement, but already usable for
casual games.

@item
@uref{https://github.com/pcapriotti/kaya, Kaya}, a small KDE-based GUI
successor to Tagua, but development of this still young program seem
to have stalled.

@item
@uref{http://www.gnu.org/software/xboard/, XBoard/Winboard}, a GUI for
much more than Shogi, part of the GNU Project.  Patches for GNU Shogi
to support it are being integrated into the developement version,
1.4.x and earlier versions cannot talk to it.

@item
@uref{http://ftp.gnu.org/gnu/gnushogi/, XShogi}, an X-Window graphical
interface to gnushogi, forked off GNU XBoard years ago, and far from
today's UI standards. It has barely been maintained recently, while
XBoard has grown much and is able to play Shogi, and will be soon
retired.

The GNU Shogi distribution used to contain the 'xshogi' program, In
future versions, GNU Shogi will be able to use XBoard as a GUI and
XShogi will be retired.  XShogi is still available as a separate
source archive on the GNU project FTP server.

@end enumerate


Disclaimer: I use the personal pronouns ``him'', ``his'' etc. to refer
to a shogi player regardless of gender.  That's easier than writing
``his or her'' all over the place.  I don't mean to infer that women
don't play shogi; in fact shogi is very popular in Japan among women as
well as men.


@node    About shogi, gnushogi, Introduction, Top
@chapter About the game of shogi
     

@quotation
``Japanese chess cedes nothing in depth or beauty to the European
game... it is at least as interesting.''

--- Alexander Alekhine @*
(quoted in David Pritchard, @cite{The Encyclopedia of Chess Variants}) 

``... shogi [is] by far the most complex form of chess that has ever
achieved widespread popularity.''

--- R. Wayne Schmittberger, @cite{New Rules for Classic Games}
@end quotation

Shogi is the version of chess played in Japan.  It is strikingly
different from standard chess (which I shall refer to henceforth as
``international chess'') and also to all other regional variants,
because captured pieces can re-enter play on the side of the capturer.
This has several interesting effects on the play of the game:

@enumerate
@item
Shogi is much more complex than international chess, at least in
terms of the average number of possible moves per turn (estimated at
about 35 for chess and at about 80 for shogi).

@item
There are almost no draws (about 1-2% of all games in professional play).

@item
Exchanges complicate the play rather than simplifying it.

@item
There are no ``endgames'' in the standard chess sense; all pieces remain
in play throughout the game.  Games typically end in a race to
checkmate the other player before being checkmated oneself.

@item
Ownership of a piece is not indicated by the color of the piece;
instead, pieces are wedge-shaped and point towards the opponent.  The
name of the piece is inscribed in Kanji characters on the front of the
piece.

@item
Most importantly: it's more fun than other forms of chess :-)

@end enumerate

Shogi is extremely popular in Japan; it has been estimated that 20
million Japanese can play shogi, of which perhaps 1 million are active
players.  It is even more popular there than the game of go, Japan's
other favorite board game.  There are a number of professional players
who make a considerable amount of money playing in shogi tournaments,
and the game receives extensive newpaper and television coverage.
Despite this, the game has yet to become popular outside of Japan.  Part
of this is because the Kanji characters on the pieces scare away some
people, but mostly it's due, I think, to lack of exposure to the game
and to the difficulty of finding opponents.  I hope that GNU shogi will
help introduce shogi to a wider audience.

@ifnottex
@menu
* The rules of shogi::
* Sample game::
* Mating problems::
* Shogi variants::
* Differences between shogi and chess::
@end menu
@end ifnottex


@c -------------------------------------------------------
@c 
@c The rules of shogi.
@c
@c -------------------------------------------------------

@node    The rules of shogi, Sample game, About shogi, About shogi
@section The rules of shogi
@cindex  Rules

Shogi is a two-person abstract strategy board game with full information
(i.e. all pieces and moves are visible to both players at all times).
It is in the chess family, being descended from the same ancestral game
as international chess: the Indian game of Chaturanga.  The two players
are referred to as ``Black'' and ``White'', with Black moving first
(unlike in international chess, where White moves first), and with
movement alternating between the two players.  Note that ``Black'' and
``White'' are just names; the pieces are not colored.  Instead, they are
flat, wedge-shaped pieces which point towards the opponent.  The
identity of a given piece is indicated by two Japanese Kanji characters
on each piece.  In fact, only the top character is needed to identify
the piece and thus only the top character is used in shogi diagrams.  I
will use alphabetical equivalents in the diagrams here; to see what the
Kanji characters look like, start up a graphical interface
(@pxref{Introduction}) and compare the starting setup there with the
starting setup in this file (@pxref{The opening setup}).

The object of the game is to capture the opponent's King.  The board is
a grid of 9x9 uncolored squares, and pieces are placed on the squares.
Each player begins with 20 pieces, described in the next section.
Capture is by displacement, as in international chess.

@ifnottex
@menu
* The moves of the pieces::
* The opening setup::
* Promotion of pieces::
* Drops::
* Winning the game::
* Draws::
* Handicaps::
* Notes for chess players::
@end menu
@end ifnottex

@c The moves of the pieces.

@node       The moves of the pieces, The opening setup, The rules of shogi, The rules of shogi
@subsection The moves of the pieces
@cindex     Piece moves

Each player at the beginning of a shogi game has a total of 20 pieces of
eight different types.  The moves of the shogi pieces can be divided
into three classes: ``stepping'' pieces, that only move one square at a
time; ``ranging'' pieces that move any number of unobstructed squares in
a line, and ``jumping'' pieces that can jump over obstructing pieces to
reach their destination squares.  Most pieces can also promote to
different (usually stronger) pieces under certain circumstances (see the
next section).  All pieces capture the same way that they move (even
pawns).  The piece moves and promotions are as follows; each piece name
is followed by the standard piece abbreviation:

@enumerate

@item
The king (K).  The king can move one square in any horizontal, vertical,
or diagonal direction, just like the king in international chess.  The
king does not promote.

@item
The rook (R).  The rook can move any number of squares in a horizontal
or vertical direction.  The rook is the same as the rook in
international chess (except that it can promote).  A rook promotes to a
``dragon king'' or ``dragon'' for short (often just referred to as a
``promoted rook''), which can move as a rook or can move one square in
any diagonal direction.

@item
The bishop (B).  The bishop can move any number of squares in a diagonal
direction.  The bishop is the same as the bishop in international chess
(except that it can promote).  A bishop promotes to a ``dragon horse''
or ``horse'' for short (often just referred to as a ``promoted
bishop''), which can move as a bishop or can move one square in any
horizontal or vertical direction.  Note: the horse should not be
confused with a knight (see below), as they are two completely different
pieces.

@item
The gold general (G).  A gold general can move one square in any
horizontal or vertical direction, or one square in a forward diagonal
direction.  Gold generals do not promote.

@item
The silver general (S).  A silver general can move one square in any
diagonal direction, or one square straight forward.  A silver general
promotes to a gold general.

@item
The knight (N).  A knight can move one square straight forward followed
by one square to either forward diagonal, jumping over intervening
pieces if any.  In other words, a knight moves like its international
chess counterpart, but forward only.  A knight promotes to a gold
general.  The knight is the only jumping piece, as in chess.

@item
The lance (L).  A lance can move any number of squares straight forward.
A lance promotes to a gold general.

@item
The pawn (P).  A pawn can move one square straight forward.  The pawn
captures the same way that it moves, in contrast to international chess.
There is also no initial two-space move for pawns and no
@emph{en-passant} capture.  A pawn promotes to a gold general; a
promoted pawn is usually known as a ``Tokin''.

@end enumerate


@c The opening setup.

@node       The opening setup, Promotion of pieces, The moves of the pieces, The rules of shogi
@subsection The opening setup
@cindex     Opening setup

The opening setup for shogi is as follows:

@ifnottex
@verbatim
   9    8    7    6    5    4    3    2    1
+--------------------------------------------+
| wL | wN | wS | wG | wK | wG | wS | wN | wL |  a
+--------------------------------------------+
|    | wR |    |    |    |    |    | wB |    |  b
+--------------------------------------------+
| wP | wP | wP | wP | wP | wP | wP | wP | wP |  c
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  d
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  e
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  f
+--------------------------------------------+
| bP | bP | bP | bP | bP | bP | bP | bP | bP |  g
+--------------------------------------------+
|    | bB |    |    |    |    |    | bR |    |  h
+--------------------------------------------+
| bL | bN | bS | bG | bK | bG | bS | bN | bL |  i
+--------------------------------------------+
@end verbatim
@end ifnottex

@c The following TeX macros are taken with permission from 
@c "TeX for the Beginner" by Wynter Snow.

@tex
\def\startline{\par\nobreak\noindent}

{\obeylines\obeyspaces%
\gdef\beginVerbatim{\bigbreak%
\begingroup%
\parskip=0pt%
\obeylines\obeyspaces%
\let^^M=\startline%
\tt}}
\gdef\endVerbatim{\endgroup\bigbreak}
\beginVerbatim


   9    8    7    6    5    4    3    2    1
+--------------------------------------------+     
| wL | wN | wS | wG | wK | wG | wS | wN | wL |  a   
+--------------------------------------------+     
|    | wR |    |    |    |    |    | wB |    |  b   
+--------------------------------------------+     
| wP | wP | wP | wP | wP | wP | wP | wP | wP |  c   
+--------------------------------------------+     
|    |    |    |    |    |    |    |    |    |  d   
+--------------------------------------------+     
|    |    |    |    |    |    |    |    |    |  e   
+--------------------------------------------+     
|    |    |    |    |    |    |    |    |    |  f   
+--------------------------------------------+     
| bP | bP | bP | bP | bP | bP | bP | bP | bP |  g   
+--------------------------------------------+     
|    | bB |    |    |    |    |    | bR |    |  h   
+--------------------------------------------+     
| bL | bN | bS | bG | bK | bG | bS | bN | bL |  i   
+--------------------------------------------+

\endVerbatim
@end tex

Here, ``b'' stands for ``black'' and ``w'' stands for ``white'', so
that, for instance, ``bL'' means ``black lance''.  The numbers above the
files and the letters to the right of the ranks represent the most
common notation system used for shogi by westerners (the Japanese also
use Arabic numerals for the files but use Japanese numerals for the
ranks).  


@c Promotion of pieces.

@node       Promotion of pieces, Drops, The opening setup, The rules of shogi
@subsection Promotion of pieces
@cindex     Piece promotion

In sharp contrast to international chess, where only pawns can promote
to higher-ranked pieces, most of the pieces in shogi can promote.  The
promoted ranks are discussed in the section on piece moves (@pxref{The
moves of the pieces}) but are repeated here for reference:

@table @asis

@item Pawn
promotes to gold general (called a `tokin' in this case only).

@item Lance
promotes to gold general.

@item Knight
promotes to gold general.

@item Silver general
promotes to gold general.

@item Gold general
does not promote.

@item Bishop
promotes to ``dragon horse'' or just ``horse'' for short.  The horse can
move as a bishop or can move one square in any orthogonal direction.

@item Rook
promotes to ``dragon king'' or just ``dragon'' for short.  The dragon
can move as a rook or can move one square in any diagonal direction.

@item King
does not promote.

@end table

The three ranks furthest away from each player constitute his/her
``promotion zone''.  A player may, but is not required to, promote a
piece after making a move in which the piece begins and/or ends in the
promotion zone.  Thus you can promote a piece when moving the piece into
the promotion zone, out of the promotion zone, or entirely within the
promotion zone.  Promotion is mandatory in these cases:

@enumerate

@item You must promote a pawn or a lance after moving it to the last rank.

@item You must promote a knight after moving it to either of the last
two ranks.

@end enumerate

These forced promotions ensure that a piece cannot be moved to a square
from which it would have no further move.

Pieces ``dropped'' onto the board (@pxref{Drops}) always drop in the
unpromoted state, even if they drop into the promotion zone.



@c Drops.

@node       Drops, Winning the game, Promotion of pieces, The rules of shogi
@subsection Drops
@cindex     Drops

When a player captures a piece, that piece is not removed from play.
Instead, it becomes the property of the capturer and can re-enter play
by being placed on (almost) any vacant square during the player's move.
This is known as a ``drop'' and counts as a full move (in other words,
you can either move a piece on the board or drop a piece onto the board
during your move, but not both).  All pieces drop in the unpromoted
state.  Pieces may be legally dropped in their promotion zone, but they
do not promote on that turn.

There are several restrictions on drops:

@enumerate

@item A pawn may not be dropped onto a file if there is already an
unpromoted pawn belonging to the same player on that file.  It is legal
to drop a pawn on a file which contains a @emph{promoted} pawn belonging
to the same player, however.

@item A pawn may not be dropped to give immediate checkmate on the
move.  A pawn is, however, permitted to be moved on the board to give
immediate checkmate.  This is a curious rule, and if anyone knows the
reason for it I would appreciate it if they would contact me and explain
it to me :-)

@item A pawn or piece may not be dropped onto a square from which they
would have no legal move.  This means that pawns and lances may not be
dropped onto the last rank, and the knight may not be dropped onto the
last or second-to-last rank.

@end enumerate

It is entirely permissible (and often advisable) to drop a piece or pawn
between one's King and an attacking ranging piece.  For this reason,
the final checkmating move is nearly always an attack on the King from
an adjacent square (except for an attack by a Knight).

Captured pieces are said to be pieces ``in hand''.

The drop is the primary distinguishing feature of Japanese chess, shared
with no other popular chess-type game.  It gives shogi a very aggressive
quality, and dramatically increases the number of possible moves once a
few pieces have been captured.  Another interesting feature of shogi is
that exchanges complicate play rather than simplifying it (as in
international chess), because of the drop rule.


@c Winning.

@node       Winning the game, Draws, Drops, The rules of shogi
@subsection Winning the game
@cindex     Winning the game

A game of shogi is won by capturing the opponent's king.  In general,
this is done by checkmating the king: attacking the king in such a way
that the king cannot be defended no matter what the defending player
moves.  Note, though, that there is no rule that requires a player to
defend a king which is being attacked.  However, if he does not defend
his king, the opponent is entirely free to capture it on the next move,
thus winning the game.  As in international chess, in practice most
games end by resignation when one player realizes that he cannot escape
checkmate. 


@c Draws.

@node       Draws, Handicaps, Winning the game, The rules of shogi
@subsection Draws
@cindex     Draws

There are very few draws in shogi; only about 1-2% of professional games
end in a draw.  One reason for this is that material can never be
depleted as in chess, because captured pieces are constantly re-entering
play as a consequence of the drop rule.  In fact, most of the ways a
game can be drawn in chess are not allowed in shogi:

@itemize @bullet

@item Draws cannot be offered.

@item There is no fifty-move rule.

@item A stalemate counts as a win for the stalemater.  Stated otherwise:
if you can't move, you lose.

@item Perpetual check is illegal (see below).

@end itemize

There are only two legal ways in which a draw can occur:

@enumerate

@item A position (including the pieces in hand) occurs 4 times with the same
player to move (called ``Sennichite'').  However, if this is caused by
consecutive checks (direct attacks on the King, threatening to capture
it on the next move) by one side, the player giving these checks loses
the game.  In other words, perpetual check results in a loss for the
attacker who recreates the same position the 4th time.

@item Both players have moved their King into the the promotion zone (or they
cannot be prevented from doing so) and the Kings cannot be checkmated.
A King who has entered the promotion zone is known as an ``entering
King''; due to the forward orientation of most shogi pieces, it is very
hard to mate such a King.  In that case the players may decide to count
their pieces as follows: the King does not count, the Rook and Bishop
count as 5 points, and all other pieces as one point.  Promotion is
disregarded.  If both players have at least 24 points the game is a draw
(called ``Jishogi'').  If a player has less, he loses the game.

Of course, a player can refuse to count pieces when he still has mating
chances or chances to gain material which would affect the outcome of
the counting.  There is no strict rule about what to do if this is not
the case, but nonetheless a player refuses to count up (e.g. because he
does not have enough points for a draw).  It has been generally accepted
that in such a case the game ends and the pieces are counted after one
player has managed to get all his pieces protected in the promotion
zone.

@end enumerate

@c Handicaps.

@node       Handicaps, Notes for chess players, Draws, The rules of shogi
@subsection Handicaps
@cindex     Handicaps

Unlike international chess, shogi has a well-established handicap system
which is used when players of different strengths play against each
other.  Handicaps range from small to huge, which makes it possible for
weak players to play against even very strong players and have an even
chance of winning.

Shogi players are ranked as follows: the weakest rank is around 15
``kyu'', which represents a beginner.  14 kyu is higher than 15 kyu, 13
kyu is higher still, and so on until you get to 1 kyu.  The next highest
rank is 1 ``dan'', followed by 2 dan, 3 dan and so forth.  The highest
amateur rank is 6 dan; professionals go up to 9 dan.  However,
professional ranks are not the same as amateur ranks; a professional 1
dan is @emph{much} stronger than an amateur 1 dan.  This system is
similar to that used by go players (and also other Japanese sports such
as karate).

A handicap consists of the stronger player playing White and removing
one or more pieces from his side of the board at the start of the game.
These pieces are permanently removed from play; they are not in hand.

The following is a list of the accepted handicaps, from weakest to
strongest.  The degree of the handicap, represented by the position in
the list, represents the difference in rank between the two players for
which the handicap is appropriate.  These rules are taken from the books
``Shogi for Beginners'' by John Fairbairn and ``The Art of Shogi'' by
Tony Hoskings (@pxref{References and links}) and, I believe, represent
current Japanese practice.

@enumerate

@item 
The stronger player removes his left lance (on 1a).

@item 
The players play a two-game match; in the first game the stronger player
removes his left lance (on 1a), while in the second game he removes his
bishop.

@item 
The stronger player removes his bishop.

@item 
The stronger player removes his rook.

@item 
The stronger player removes his rook and left lance.

@item 
The players play a two-game match; in the first game the stronger player
removes his rook and left lance (on 1a), while in the second game he
removes his rook and bishop.

@item 
The stronger player removes his rook and bishop.  This is usually called
a ``two-piece'' handicap.

@item 
The stronger player removes his rook, bishop, and both lances.  This is
called a ``four-piece'' handicap.

@item 
The stronger player removes his rook, bishop, both lances, and both
knights.  This is called a ``six-piece'' handicap.

@item 
The stronger player removes his rook, bishop, both lances, both knights,
and both silvers.  This is called an ``eight-piece'' handicap.

@end enumerate

Another advantage of playing handicap games is that the handicaps alter
the optimal strategy for both players.  For instance, handicaps all have
their own opening lines which may bear little or no resemblance to those
used in non-handicap shogi.  This means that when learning handicap
shogi, you are essentially learning completely new games which use the
same equipment!

The reader may wonder how on earth a player giving an eight-piece
handicap, say, could possibly hope to win.  Don't forget, though, that
in shogi the opponent's pieces can be captured and then become part of
one's own army.  Thus, if the opponent plays badly enough, the number of
pieces will soon even out.


@c Notes for chess players.

@node       Notes for chess players,  , Handicaps, The rules of shogi
@subsection Notes for chess players

Here are a few miscellaneous things that may confuse chess players.
Some of these have been mentioned elsewhere, but they bear repeating.

@enumerate
@item There is no queen.

@item Pawns capture the same way they move.  There is no initial
two-space pawn move and no @emph{en-passant} move.

@item There is no special castling move.  There @emph{are} a large
number of possible defensive formations referred to as ``castles''
(@pxref{Sample game}) but there is no need for special moves to create
them.

@item A given piece can only promote to @emph{one} other kind of piece.

@end enumerate

@c 
@c Sample game.
@c 

@node    Sample game, Mating problems, The rules of shogi, About shogi
@section Sample game
@cindex  Sample game

@c This will have to be spruced up for the TeX version...

This game was annotated by Pieter Stouten (@pxref{References and
links}).  I have made some minor corrections.  Note that captures are
denoted by the ``x'' symbol e.g. Rx3f and drops are denoted by the ``*''
symbol e.g. R*3f.  Check is indicated by a ``+'' after the move,
e.g. R3f+.  I recommend you use a graphical interface to play along with this
game.  In xshogi simply hit the ``Force Moves'' button after starting
up, while in gnushogi enter the word ``force'' at the prompt.  This will
allow you to enter moves for both sides.

Note also that the move numbering system used here is the chess-type
system where one move means one move by each player.  The Japanese count
one move made by each player as two moves.

---------------------------------------------------------------------------

Below you will find (the English translation of) an annotated game which
was published in the Dutch Shogi magazine ``81'' and in the Dutch
beginners booklet.  It has proven to be a very useful game to explain
some basic principles of Shogi.  Also, it is a rather straightforward
game compared to professional games where in most cases very diffuse
middle game fights take place.

   Pieter Stouten, 14th May 1990.

---------------------------------------------------------------------------

Black: Michael Trent (1-dan).  White: David Murphy (2-dan).

   1. P2f P3d  2. P2e B3c @*
[ This move is necessary, as otherwise white can exchange pawns: 3. P2d
Px2d 4. Rx2d.  He would thus get a pawn in hand and open up his rook
file. ]

   3. P7f P4d @*
[ White closes the bishop diagonal again.  He plans to play ranging rook
(the rook goes to 5b, 4b, 3 or 2b; a defensive strategy) and in that
case he'd better avoid an exchange of bishops.  One of the reasons is
that he will have problems developing his pieces without leaving holes
for bishop drops. ]

   4. S4h R3b  5. P3f S4b  6. K6h K6b @*
[ In general the rook plays an important role in the attacks.  It is
wise to move the king away from the area where the initial fights will
be and both players act according to the Shogi proverb ``keep the rook
and king apart''. ]

   7. K7h K7b  8. P5f P5d  9. G4i-5h G4a-5b @*
[ Both players use their second gold general to build their castle. ]

   10. S6h @*
[ In itself this move is not bad.  However, it will become clear that
black plans a quick attack and in that case it is wiser to omit this
move. ]

   10... S5c  11. P1f P1d @*
[ The advance of the edge pawns must be timed very well.  The remark at
black's tenth move applies here too: this move is good if black wants to
play a slow game, because it eliminates a future B1e. ]

   12. P4f K8b  13. N3g S7b @*
[ Black develops his knight in order to start an attack over the second,
third and fourth files.  White strengthens his king's position and
awaits the attack.  He aims at a counterattack as soon as black has
broken through into the white camp.  Probably white's breakthrough will
take place later, but he has good compensation in the form of a stronger
castle.  This theme occurs very often in static rook versus ranging rook
games. ]

   14. P4e R4b @*
[ Black starts his attack and white puts up a very passive defence.  His
rook has a hard task now to penetrate the black position.  Moreover, he
blocks his own bishop.  It seems much better to start a counterattack
with 14... P3e, later to be followed by B2b, B5a or Bx4d in order to use
his rook more actively. ]

   15. Px4d Sx4d  16. P*4e S5c @*
[ 16... Sx4e is more active.  A silver general is normally more valuable
than a knight, but white gets two pawns in hand and black none, while
the knight might come in handy for white too. ]

   17. Bx3c+ Nx3c  18. P2d Px2d @*
[ Black threatens to break through and white has to consider taking the
pawn on 2d or starting a counterattack with Nx4e.  If he chooses the
latter, black can play Px2c+ followed by +P3c.  The disadvantage is the
black ``tokin'' (=promoted pawn) that white will get in his camp; the
advantage is that it will cost black two more moves to promote his rook.
Because white did not trust that the result after engaging in a
``semeai'' (=mutual attack) with 18...Nx4e would give a positive result,
he captured the pawn on 2d.  Making the right decision in moments like
this often makes the difference between a win and a loss: miss one
attacking chance and you will be forced to defend the whole game until
the unavoidable defeat; on the other hand, an unsound attack can destroy
all ``aji'' (=potential, meaning possibilities, threats) without getting
anything in return. ]

   19. Rx2d Nx4e  20. Nx4e Rx4e  21. R2a+ P*4g @*
[ Now it becomes clear why black's 10. S6h was not good.  Had this move
been omitted, then white would not have had the time to play 13... S7b
and after R2a+ the gold on 6a would hang.  Thus black would have kept
``sente'' (=initiative).  Instead of 21... P*4g, B*6d is a very good
move, because after 22. P*2h black does not have a pawn in hand anymore
and he is being threatened with the annoying 22... N*4f 23. G5g N3h+
24. S4g +N4h also.  Black can also counter 21... B*6d with 22. N*3g.
White would then reply with 22... R4b 23. B*3c P*4g 24. Bx4b+ Sx4b.  The
white rook has played its role and instead of spending moves on saving
it white starts to scatter black's defences by successive pawn drops on
the fourth file: 25. Gx4g P*4f 26. G5g N*6e 27. G5h P4g+ 28. Gx4g P*4f.
This analysis was provided by Kato Hifumi, 9-dan professional (the
highest regular grade).  Destroying the coherence of the enemy pieces
(their shape) by dropping pawns is one of the most important Shogi
techniques.  With the actual move 21... P*4g white missed a good
chance. ]

   22. Sx4g P*4f  23. B*3g Px4g+  24. +Rx6a +Px3g @*
[ 23. B*3g seems pointless, but a closer look reveals that it is
actually quite mean.  On move 24 white cannot capture black's ``Ryu''
(=dragon =promoted rook) with his silver: 24... Sx6a 25. N*7d K7b
26. G*8b mate.  By attacking the front of the white castle and
threatening to mate him there, black has the chance to break down the
white defences from the side. ]

   25. +Rx5b S*6b @*
[ Here 25... B*4d would be much better, because it is defensive and
attacking at the same time.  After e.g. 26. G*4c Bx9i+ 27. Gx5c black
threatens 28. +Rx7b Kx7b 29. S*6a K8b 30. S*7a Kx7a 31. G*7b mate.
White is one move quicker, however.  He has the following beautiful
``tsume'' (mating sequence where every move is check): 27... N*8f 28. Px8f
S*8g 29. Kx8g B*9h 30. K7h Bx8i+ 31. K8g +B8i-8h 32. K9f L*9e mate.
This illustrates the sharpness of Shogi: one move can make the
difference between winning and losing. ]

   26. P*4f Rx4f @*
[ This move eliminates white's last chances.  26... R4b 27. +Rx4b Sx4b
28. R*4a seems annoying, but after 28... B*3c 29. S7g B*3b white wins
the rook and with his ``tokin'' on 3g there still is some hope. ]

   27. N*6e +P4g @*
[ White cannot defend anymore, so he starts a desperate attack.  Black
does not lose the right track, however. ]

   28. Nx5c+ +Px5h  29. +Nx6b +Px6h  30. Gx6h N*8f  31. Px8f B*6i  32. Gx6i
   R4h+  33. N*6h +Rx6h  34. Gx6h S*8g  35. Kx8g N*9e  36. K7h Resigns @*
[ White resigns here, because after 36... B*8g 27. K7g his attack has
petered out. ]

@page


@c 
@c Mating problems.
@c 

@node    Mating problems, Shogi variants, Sample game, About shogi
@section Mating problems

One good way to improve at shogi is to solve mating problems.  There are
several types of these problems, but the most common is called a
``tsume-shogi'' problem, or ``tsume'' problem for short.  In a tsume
problem, all pieces that are not on the board are assumed to be in the
opponent's hand (except for your King, which is usually not shown).
Every move you make must be check until the final checkmate.  Your
opponent may play any piece on the board or drop any of his pieces in
hand in order to prevent the mate.  In a properly constructed tsume
problem, all of your pieces on the board and in hand must be essential
to the solution.  One consequence of this is that all of your pieces in
hand must be played during the solution.  There should only be one
correct solution for the given number of moves.  Tsume problems use
Japanese-style move numbering; thus, a problem where you move (and give
check), your opponent moves, and you move to give checkmate is called a
three-mover.  Here is a really trivial three-mover:

@ifnottex
@verbatim
   3    2    1
----------------+
 |    |    |    |  a
----------------+
 |    |    | wK |  b
----------------+
 |    |    |    |  c
----------------+
 | bN |    |    |  d
----------------+
 |    |    |    |  e
----------------+
 |    | bN |    |  f
----------------+

Black in hand: S, G
@end verbatim
@end ifnottex


@tex
\def\startline{\par\nobreak\noindent}

{\obeylines\obeyspaces%
\gdef\beginVerbatim{\bigbreak%
\begingroup%
\parskip=0pt%
\obeylines\obeyspaces%
\let^^M=\startline%
\tt}}
\gdef\endVerbatim{\endgroup\bigbreak}
\beginVerbatim

   3    2    1            
----------------+         
 |    |    |    |  a         
----------------+           
 |    |    | wK |  b         
----------------+           
 |    |    |    |  c       
----------------+         
 | bN |    |    |  d       
----------------+         
 |    |    |    |  e       
----------------+         
 |    | bN |    |  f       
----------------+
     
Black in hand: 2G

\endVerbatim
@end tex

Here, Black plays G*2b, White plays K1c, and Black plays G*1d mate.
More typical tsume problems range from 5 moves to arbitrarily high
numbers of moves, and they can be quite brain-busting.  Tsume problems
may seem artificial, but in the closing stages of the game where both
players have a lot of pieces in hand, it is often necessary to give
check at every move, or else your opponent will start a counterattack
and will mate you before you mate him.  A tsume problem is a worst-case
scenario for the attacker: you have to mate your opponent even though he
has every piece not on the board in hand, which means you have to
develop sharp attacking skills.  Many more tsume problems can be found
on the internet; I particularly recommend Patrick Davin's ``Shogi
Nexus'' (@pxref{References and links}).

@page

@c 
@c Shogi variants.
@c 

@node    Shogi variants, Differences between shogi and chess, Mating problems, About shogi
@section Shogi variants
@cindex  Shogi variants
@cindex  Variants
@cindex  Tori Shogi
@cindex  Wa Shogi
@cindex  Chu Shogi
@cindex  Dai Shogi
@cindex  Tenjiku Shogi
@cindex  Dai-dai Shogi
@cindex  Maka-dai-dai Shogi
@cindex  Tai Shogi
@cindex  Kyoku Tai Shogi

Several historical variants of shogi exist.  Most of these were invented
before modern shogi (in some cases hundreds of years before), are much
larger than modern shogi and are not played with drops.  Thus, in many
ways they are really more like giant chess games than like modern shogi.
The only one of these games to have survived in Japan is Chu (middle)
shogi, which is still played a little bit.  Thanks to the efforts of
George Hodges and John Fairbairn of the Shogi Association (two British
shogi enthusiasts), these games were resurrected and rules and sets for
them can still be purchased from George Hodges (@pxref{References and
links}).  I hope to eventually extend GNU shogi so that it can play at
least some of these games.  There are also several non-historical
variants of shogi; I don't know much about them but you can find
information about them on the internet (@pxref{References and links}).

The historical variants include:

@enumerate

@item
Tori (bird) shogi, played on a 7x7 board with 32 pieces in all; this is
the only variant that is known to have been played with drops.

@item
Wa shogi, played on an 11x11 board with 54 pieces.  This game can be
played with or without drops but the historical evidence favors the view
that it was played without drops.  However, most people who have tried
it claim it is a much better game with drops, being even more intricate
than standard shogi.

@item
Chu (middle) shogi, played on a 12x12 board with 92 pieces.  This was
(and is) by far the most popular of the variants, and has 21 different
kinds of pieces in the starting line-up alone (along with several others
that appear upon promotion).  Unlike modern shogi, there are a
tremendous number of ranging pieces and the game is definitely not
played with drops.  There is also an amazing piece called the Lion which
has a double king move and can capture two pieces at once!  Chu shogi
has a small but fanatical following, some of whom consider it better
than modern shogi.

@item
Dai (great) shogi, played on a 15x15 board with 130 pieces.  Other than
the larger board, this game is very similar to Chu shogi.

@item
Tenjiku (exotic) shogi, played on a 16x16 board with 176 pieces.  This
game is possibly the most complex tactical game in existence.  There are
many astoundingly powerful pieces, including one (the Fire Demon) that
can capture up to eight opposing pieces in a single move!  Despite the
size of the game, checkmates can occur very suddenly (and often very
early on) if one player makes a wrong move.  Tenjiku also has a small
but fanatical following, one of whom (Colin Adams) has written a book on
the game which is available for download at
@uref{http://wayback.archive.org/web/20120717085827/http://www.colina.demon.co.uk/tenjiku.html}.

@item
Dai-dai (great-great) shogi, played on a 17x17 board with 192 pieces.
The opening setup alone has 64 different kinds of pieces!  This game and
the larger ones that follow sound pretty outlandish, but they have
actually been played; a game of Dai-dai can supposedly be played in
about 12 hours.

@item
Maka-dai-dai (great-great-great) shogi, played on a 19x19 board with 192
pieces.  For those for whom Dai-dai shogi is just too small :-)

@item
Tai (grand) shogi, played on a 25x25 board with 354 pieces!  Until
recently, this was thought to be the biggest chess game ever devised,
but now there is...

@item
Kyoku tai (extremely grand?) shogi, played on a 36x36 board with 402
pieces.  The rules for this have just been unearthed in an old Japanese
book.  Hopefully someone will soon organize a postal Kyoku tai shogi
championship; maybe their distant ancestors could finish it :-)

It is thought that the really huge games (Dai-dai and up) were never
really played to any significant extent (gee, wonder why?) and were
devised merely so that the creators could have the fun of inventing
enormous games, amazing their friends and confounding their enemies.
However, the games up to Tenjiku shogi at least appear to be quite
playable, assuming one has the time.

@end enumerate

Many modern variants have also been devised, usually on small boards,
and often by western people.  Those include:

@enumerate

@item
Mini Shogi, played on a 5x5 board with 12 pieces.  Its rules are
nearly identical to Standard Shogi, and GNU Shogi has some support for
it.

@item
Judkins Shogi, similar to Mini Shogi on a 6x6 board.

@item
Cannon Shogi, played on a 9x9 board, adds pieces inspired by the
Cannon found in Xiang Qi (chinese chess)

@item
Sannin Shogi, a 3-player variant on an hexagonal board, with specific
rules governing alliance between two players

@item
Kyoto Shogi, Micro Shogi, and several others are much more different.

@end enumerate

@c
@c Differences between shogi and chess.
@c

@node    Differences between shogi and chess,  ,  Shogi variants, About shogi
@section Differences between shogi and chess
@cindex  Shogi vs. Chess

Some differences between shogi and international chess have been
mentioned elsewhere in this document; I summarize them here for people
who are interested in game comparisons.  I won't try to deal with the
thorny question of which game is ``better'' although my bias may have
already come through :-) In fact, the drop rule makes the two games so
different in character that arguing over which game is better is like
comparing apples to oranges (you'd be better off comparing chess to Chu
shogi (@pxref{Shogi variants}).  However, I believe that if you are a
chess fan you'll really like shogi as well, and shogi is also popular
with many people who don't particularly like chess.

Here are the significant differences between chess and shogi:

@enumerate

@item
In shogi, captured pieces become the property of the capturer and can
re-enter play by being dropped onto almost any vacant square.  In chess,
captured pieces are out of the game.  Thus, in shogi, piece exchanges
complicate the play significantly while in chess they simplify it.

@item
The shogi board is 9x9; the chess board is 8x8.

@item
Shogi has five pieces with no counterpart in chess: the gold and silver
generals, the lance, the promoted rook and the promoted bishop.  Chess
has one piece with no counterpart in shogi: the queen.  The knight's
move in shogi is much more restrictive than in chess.  Pieces in shogi
generally have a much smaller range of movement than in chess (unless
they are in hand).

@item
In shogi, all pieces except the gold general and the king can promote,
but only to one kind of piece.  Promotion is easier in shogi because the
promotion zone is closer to the starting position of the pieces
(especially pawns).  In chess, only the pawn can promote, but it can
promote to any other piece except the king.

@item
In shogi, pawns capture the same way they move.  There is no initial
two-space pawn move and hence no @emph{en-passant} captures.  In chess,
pawns capture diagonally which means that opposing pawns can block each
other.

@item
In shogi, you only have one rook and one bishop.  Note that the bishop
is not restricted to only one ``color'' square (squares in shogi aren't
colored, but never mind) because promoted bishops can also move one
square orthogonally.

@item
There is no special castling move in shogi.  The term ``castle'' is
used in shogi to denote a defensive formation consisting of (usually)
three generals which protect the king.  There are many such castles
(about 40 or so have names).  @xref{Sample game}.

@item
Draws are much rarer in shogi than in chess.  Perpetual check is not
allowed.  Stalemate is a virtual impossibility, and is a loss for the
stalematee. 

@item
Since pieces are never out of play in shogi, chess-type endgames
involving only a few pieces do not occur.

@item
Shogi games are generally longer than chess games (about 60-70 moves is
typical).

@item
Shogi has a well-developed handicap system which is in general use;
chess does not.

@end enumerate

The effects of all these differences on play include (in my opinion):

@enumerate

@item
Piece/pawn structures in chess are more rigid than in shogi.  Pawns
block each other and pawns, once advanced, cannot ever retreat.  In
shogi, you can repair the hole caused by a pawn advance by exchanging
the pawn and dropping it back where you want it.  Thus shogi is more
fluid than chess and less ``structural''.

@item
Counterattack is MUCH more common in shogi than in chess.  Games
typically end in mutual mating attacks, where each player is trying to
checkmate the other player before being checkmated himself.  This makes
tempo incredibly important and also makes sacrificial play quite common.

@item
Attacks involving only ranging pieces are more a feature of chess than
of shogi.  A shogi attack typically uses a ranging piece or pieces to
support an attack by short-range pieces (especially generals).  It is
very rare to mate a king with a non-adjacent ranging piece in shogi
since the player whose king is threatened can almost always interpose by
dropping a piece.

@end enumerate


@c --------------------
@c gnushogi.
@c --------------------

@node    gnushogi, References and links, About shogi, Top
@chapter gnushogi
@cindex  gnushogi

This section describes how to run the ``gnushogi'' program.

SYNOPSIS
     
gnushogi [ [[-]a] [-b bookfile] [-B binbookfile] [-C] [-h langfile] 
[-L langfile] [-r length] [-R] [-s pathname] [-l pathname] [-S binbooksize]
[-t] [-c size] [-T size] [-v] [-x] [-X] arg1 arg2 ]

DESCRIPTION

GNU shogi (gnushogi) plays a game of japanese chess (shogi) against the
user or it plays against itself.

At startup gnushogi reads the binbook file if it is present.  It then
looks for a book file.  If it is present it adds its contents to the
binbook data.  If the binbook file is writable a new combined binbook
file is written.

Gnushogi is a modified version of the gnuchess program.  It has a simple
alphanumeric board display, or it can be used with the xshogi program
under X windows.  The program gets its opening moves from the file
gnushogi.bbk which is located in a directory specified in the Makefile.
To invoke the program type:

@table @samp

@item  gnushogi -C
simple curses based version

@item  gnushogi -X (or just gnushogi)
xshogi compatible version

@item gnushogi -R
raw test display version
@end table

TIME CONTROLS

If one argument is given, it is the search time per move in
[minutes:]seconds.  So gnushogi 30 will generate one move every 30
seconds, while gnushogi 5:00 will generate one move every 5 minutes.

If two or more arguments are given, they will be used to set tournament
time controls with the first argument of each pair being the number of
moves and the second being the total clock time in minutes[:seconds].
Thus, entering gnushogi 60 5 will set the clocks for 5 minutes (300
seconds) for the first 60 moves, and gnushogi 30 3:30 will allow 3
minutes and 30 seconds for 30 moves.

gnushogi 30 5 1 :30 will allow 5 minutes for the first 30 moves and 30
seconds for each move after that.  Up to 4 pairs of controls may be
specified.

If no argument is given the program will prompt the user for level of
play.

@page

BOOK

The book gnushogi.tbk consists of a sequence of openings.  An opening
begins with a line starting with a # (the rest of the line is a comment).
Following this is a series of moves in algebraic notation alternating
between black and white separated by whitespace.  A move may have a ?
after it indicating this move should never be made in this position.  Moves
are stored as position:move so transpositions between openings can take
place.

HASHFILE

The hashfile if created should be on the order of 4 megabytes; you can
create such a hashfile by typing ``gnushogi -c 22'' (see below).  This
file contains positions and moves learned from previous games.  If a
hashfile is used the computer makes use of the experience it gained in
past games.  Tests run so far show that it plays no worse with the
hashfile than without, but it is not clear yet whether it provides a
real advantage.

LEGAL MOVES

Note: Piece letters are determined by the language file.  What is
specified here is the default (English).

Once gnushogi is invoked, the program will display the board and prompt
the user for a move.  To enter a move, use the notation 7g7f where the
first letter-number pair indicates the origin square and the second
letter-number pair indicates the destination square.  An alternative is
to use the notation P7f where the first letter indicates the piece type
(P,L,N,S,G,B,R,K).  To promote append a + the type of the new piece to
the move, as in 2d2c+ or P2c+. Note that you must use capital letters
for the pieces by default.

COMMAND-LINE OPTIONS

@table @samp

@item -a
Do not search on opponent's time.

@item a
Do search on opponent's time.

@item -b @var{bookfile}
Use bookfile for opening book.

@item -B @var{binbookfile}
Use binbookfile for binary opening book.

@item -c @var{size}          
Create a new HASHFILE.  File size is 2^size entries of approximately 65+?
bytes.

@item -C
Use curses-based display mode.

@item -h   
Do not use hashfile.

@item h    
Do use hashfile.

@item -l @var{pathname}
Pathname of the loadfile used with get or xget.

@item -L @var{lang}
Use language lang from the file gnushogi.lang.  If -L is not specified
it uses the first language in the file.

@item  -P @var{plylevels}
Number of plys to include in the binbookfile.  For generating a
binbookfile.

@item  -r @var{length}
Rehash @emph{length} times in searching entries for position in
transposition table.

@item  -R  
Use raw text display mode.  This can be used for dumb terminals or for
systems that don't have curses.

@item  -s @var{pathname}
Pathname of the save file to use with the save command.

@item  -S @var{size}
Size of binbookfile for memory based books.  For creating a binbookfile.

@item  -t   
Show statistics for HASHFILE.

@item  -T @var{size}
Set the transposition table size to 2^size entries.

@item  -v   
Show version and patchlevel.

@item  -x @var{value}
Use value as the evaluation window xwndw.

@item  -X   
Use xshogi display mode (the default).

@end table


COMMANDS

In addition to legal moves, the following commands can be entered at the
gnushogi prompt.  Note: command names are determined by the language
file and may vary with the implementation.  The default language is
English.

@table @samp

@item alg
allow algebraic input (not implemented).

@item Awindow 
change Alpha window (default score + 90).

@item Bwindow 
change Beta window (default score - 90).

@item beep 
toggles beeping after each move (default: on).

@item bd 
updates the current board position on the display.

@item book 
turns off use of the opening library.

@item both 
causes the computer to play both sides of a shogi game.

@item black 
causes the computer to play as White, if the computer was to move
first.

@item bsave 
saves a game to disk as a book textfile.  The program will prompt the
user for a file name.

@item gamein 
toggles game mode time control.  Assumes the time specified for time
control is the time for a complete game.  Input with the level command
should be the game time and the expected number of moves in a game.  go
command must be given.

@item coords 
show coordinates on the display (visual only).

@item contempt 
allows the value of @emph{contempt} to be modified.

@item debug 
asks for a piece as color piece, as wb or bn, and shows its calculated
value on each square.

@item debuglevel 
sets level of debugging output if compiled with debug options.

@item depth 
allows the user to change the search depth of the program.  The maximum
depth is 29 ply.  Normally the depth is set to 29 and the computer
terminates its search based on elapsed time rather than depth.  If depth
is set to (say) 4 ply, the program will search until all moves have been
examined to a depth of 4 ply (with extensions up to 11 additional ply
for sequences of checks and captures).  If you set a maximum time per
move and also use the depth command, the search will stop at the
specified time or the specified depth, whichever comes first.

@item easy 
toggles easy mode (thinking on opponents time) on and off. The default
is easy mode ON.  If easy mode is disabled, the keyboard is polled for
input every so often and when input is seen the search is terminated. It
may also be terminated with a sigint.

@item edit 
allows the user to set up a board position.
@itemize @minus

@item #    
clear the board.

@item c
toggle piece color.

@item .
command will exit setup mode.

@item p3b
place a pawn on 3b

@item p3b+
place a promoted pawn on 3b

@item p*
place a pawn in hand (among the captured pieces)

@end itemize

Pieces are entered by typing a letter (p,l,n,s,g,b,r,k)  for
the piece followed by the coordinate.  Here, letter case is ignored.

The usual warning about the language file applies.

@item exit 
exits gnushogi.

@item first 
tells the computer to move first.  Computer begins searching for a move.
(same as ``go'').

@item force 
allows the user to enter moves for both sides.  To get the program to
play after a sequence of moves has been entered use the ``black'' or
``white'' commands.

@item get 
retrieves a game from disk.  The program will prompt the user for a file
name.

@item go 
tells the computer to move first.  Computer begins searching for a move.
(same as ``first'').

@item hash 
use/don't use hashfile.

@item hashdepth 
allows the user to change the minimum depth for using the hashfile and
the number of moves from the beginning of the game to use it.

@item help 
displays a short description of the commands and the current status of
options.

@item hint 
causes the program to supply the user with its predicted move.

@item level 
allows the user to set time controls such as 60 moves in 5 minutes etc.
In tournament mode, the program will vary the time it takes for each
move depending on the situation.  If easy mode is disabled (using the
``easy'' command), the program will often respond with its move
immediately, saving time on its clock for use later on.

@item list 
writes the game moves and some statistics on search depth, nodes, and
time to the file ``shogi.lst''.

@item material 
toggle material flag - draws on no pawns and both sides < rook.

@item new 
starts a new game.

@item p 
evaluates the board and shows the point score for each piece.  The total
score for a position is the sum of these individual piece scores.

@item post 
causes the program to display the principal variation and the score
during the search.  A score of 100 is equivalent to a 1 pawn advantage
for the computer.

@item quit 
exits the game.

@item random 
causes the program to randomize its move selection slightly.

@item rcptr 
set recapture mode.

@item remove 
backout the last level for both sides.  Equal to 2 undo's.

@item reverse 
causes the board display to be reversed.  That is, the Black's pieces will
now appear at the top of the board.

@item rv 
reverse board display.

@item save 
saves a game to disk.  The program will prompt the user for a file name.

@item switch 
causes the program to switch places with the opponent and begin
searching.

@item test 
performs some speed tests for MoveList and CaptureList generation, and
ScorePosition position scoring for the current board.

@item time 
set computer's time remaining, intended for synchronizing clocks among
multiple players.

@item tsume 
toggle tsume mode. In tsume mode, not all possible moves will be
generated. If a king is in check, only moves that get the king out of
check are generated.  If the king is not in check, only moves that give
check to the opponent's king are generated.

@item undo 
undoes the last move whether it was the computer's or the human's.  You
may also type ``remove''.  This is equivalent to two ``undo'''s
(e.g. retract one move for each side).

@item white 
causes the computer to play as Black; if the computer is to move
first the go command must be given.

@item xget 
read an xshogi position file.

@item xsave 
save as an xshogi position file.

@item xwndw 
change X window. The window around alpha/beta used to determine whether
the position should be scored or just estimated.  Note: this has
@emph{nothing} to do with xshogi or X windows; the terms are completely
separate.

@end table


@c ---------------------
@c References and links.
@c ---------------------

@node    References and links, Acknowledgements, gnushogi, Top
@chapter References and links
@cindex  References
@cindex  Books
@cindex  Mailing lists
@cindex  Web sites


There are very few English-language books for people learning shogi.
The two I recommend are:

@enumerate

@item
@cite{Shogi for Beginners, 2nd. Edition}, by John Fairbairn.  This is a
superb beginner's book in every way, covering all phases of the game.
It was out of print for a long time, but has now been reprinted and is
available either from Kiseido (@uref{http://www.labnet.or.jp/~kiseido})
or from George Hodges (see below).

@item
@cite{The Art of Shogi}, by Tony Hoskings.  This is one step up from the
Fairbairn book.  It covers a lot of ground, and is especially noteworthy
for its detailed treatment of opening lines.  You can order this book
from Amazon.com's UK branch (@uref{http://www.amazon.co.uk}).

@end enumerate

Another book you may find is @cite{Shogi: Japan's Game of Strategy} by
Trevor Leggett.  This book is very elementary and is somewhat outdated,
having been published first in 1966.  However, it does feature a paper
shogi board and punch-out pieces, so if you want a really cheap shogi
set you might pick this book up.  It is still in print.

Two books that are no longer in print but are definitely worth getting
if you find them are @cite{Guide to Shogi Openings} and @cite{Better
Moves for Better Shogi}, both by Aono Teriuchi.  They are published in a
bilingual edition (English/Japanese) and are the only books on shogi in
English written by a Japanese professional shogi player.  John Fairbairn
did the translation from Japanese to English.

Shogi sets are available from:

@quotation
George F. Hodges @*
P.O. Box 77 @*
Bromley, Kent @*
United Kingdom BR1 2WT
@end quotation

George also sells equipment for all the historical shogi variants
(@pxref{Shogi variants}) (except for Kyoku tai shogi) and also sells
back issues of the magazine ``Shogi'' which he published for 70 issues
in the late 70's to late 80's.  This magazine is STRONGLY recommended;
it contains more information about shogi in English than you will ever
find anywhere else.

Here are some useful URLs:

@table @asis

@item Pieter Stouten's shogi page: @uref{http://www.shogi.net}
This is the main shogi-related site on the internet, with links to
almost all the other sites.

@item Roger Hare's shogi page: @uref{http://www.ed.ac.uk/~rjhare/shogi}
This has lots of information, including full rules to most of the shogi
variants.

@item Patrick Davin's Shogi Nexus: @uref{http://www.vega.or.jp/~patrick/shogi/}
There's lots of cool stuff on this site; my favorite is the extensive
collection of Tsume-shogi (mating) problems, both for beginners and
more advanced players.

@item Steve Evans' shogi page: @uref{http://www.netspace.net.au/~trout/index.html} 
Steve has written a program that plays almost all of the shogi variants,
unfortunately it only runs on Windows :-(

@item Hans Bodlaender's chess variant pages: @uref{http://www.cs.ruu.nl/~hansb/d.chessvar}
This page has an almost unimaginable variety of rules for different
chess variants, including many shogi variants (historical and non-historical).

@item Wikipedia's shogi variant pages: @uref{http://en.wikipedia.org/wiki/Category:Shogi_variants}
Those pages contain a large number of variant rules, both ancient and
modern.

@end table

@c -----------------
@c Acknowledgements.
@c -----------------

@node    Acknowledgements, Bugs, References and links, Top
@chapter Acknowledgements
@cindex  Acknowledgements

I would like to thank the following people:

@itemize @bullet

@item
Matthias Mutz, who originally developed GNU shogi as a spin-off of GNU
chess and who very kindly let me take over the maintenance of this very
interesting project.

@item
Richard Stallman and the Free Software Foundation, for creating an
organization where anyone can contribute software for the common good of
all, for making GNU/Linux possible, and especially for writing emacs and
gcc, without which my working life would be intolerable.

@item
Georges Hodges, for starting the Shogi Association in England, without
which I would probably never have heard of shogi, for supplying shogi
equipment, for publishing the excellent magazine ``Shogi'' (now sadly
defunct), for personally answering all my silly questions by mail, and
for being the ambassador of shogi to the West.

@item
Pieter Stouten, for having the most comprehensive shogi site on the
World Wide Web (@uref{http://www.shogi.net}), and for
maintaining the shogi-l mailing list.  Go to Pieter's web site for more
information on subscribing to the list.  Also thanks to everyone who
contributes and has contributed to that list.

@item
Matt Casters, for testing GNU shogi.  Matt and I will be working
together on improving the solution engine in future versions of this
program.

@end itemize

@c -----
@c Bugs.
@c -----

@node    Bugs, Index, Acknowledgements, Top
@chapter Bugs

The motto of GNU shogi is ``100% bug-free or you don't pay!'' :-) In
the extremely unlikely case (*ahem*) that you do find a bug, please
report it to the bug tracker at
@uref{https://savannah.gnu.org/projects/gnushogi/}.  Also, feel free
to post comments, complaints, out-and-out raves, suggestions and such
to one of the mailing lists at
@uref{https://savannah.gnu.org/mail/?group=gnushogi}.


@c ============
@c End of body.
@c ============



@c ====
@c End.
@c ====

@node    Index,  , Bugs, Top
@chapter Index

@printindex cp

@contents

@bye