+++ /dev/null
-This is gnushogi.info, produced by makeinfo version 4.3 from
-gnushogi.texinfo.
-
- This file describes how to use GNU shogi, a program which plays
-Shogi (Japanese chess).
-
- 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.
-
- 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.
-
-\1f
-File: gnushogi.info, Node: Top, Next: (dir), Prev: (dir), Up: (dir)
-
-GNU Shogi (Japanese chess)
-**************************
-
-* Menu:
-
-* Introduction:: What is GNU shogi?
-* License:: The GNU General Public License.
-* About shogi:: General information, rules, etc.
-* gnushogi:: How to play GNU shogi (gnushogi).
-* xshogi:: The X interface to GNU shogi.
-* References and links:: Where to go for more information.
-* Acknowledgements::
-* Bugs:: Where and how to report bugs.
-* Index::
-
-\1f
-File: gnushogi.info, Node: Introduction, Next: License, Prev: Top, Up: Top
-
-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 1.3.2. It was written by me,
-Mike Vanier, the current maintainer of GNU shogi. My email address is
-<mvanier@cs.caltech.edu>.
-
- GNU shogi is actually two programs:
-
-
-`gnushogi'
- is the text-based program which also contains the game-playing
- engine.
-
-`xshogi'
- is the X-windows graphical interface to gnushogi.
-
-
- Since xshogi invokes gnushogi, most players will just type "xshogi"
-and start playing.
-
- 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.
-
-\1f
-File: gnushogi.info, Node: License, Next: About shogi, Prev: Introduction, Up: Top
-
-GNU GENERAL PUBLIC LICENSE
-**************************
-
- Version 2, June 1991
- Copyright (C) 1989, 1991 Free Software Foundation, Inc.
- 675 Mass Ave, Cambridge, MA 02139, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-Preamble
-========
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-
-How to Apply These Terms to Your New Programs
-=============================================
-
- If you develop a new program, and you want it to be of the greatest
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- type `show w'.
- This is free software, and you are welcome to redistribute it
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-c'; they could even be mouse-clicks or menu items--whatever suits your
-program.
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- `Gnomovision' (which makes passes at compilers) written by James Hacker.
-
- SIGNATURE OF TY COON, 1 April 1989
- Ty Coon, President of Vice
-
- This General Public License does not permit incorporating your
-program into proprietary programs. If your program is a subroutine
-library, you may consider it more useful to permit linking proprietary
-applications with the library. If this is what you want to do, use the
-GNU Library General Public License instead of this License.
-
-\1f
-File: gnushogi.info, Node: About shogi, Next: gnushogi, Prev: License, Up: Top
-
-About the game of shogi
-***********************
-
- "Japanese chess cedes nothing in depth or beauty to the European
- game... it is at least as interesting."
-
- -- Alexander Alekhine
- (quoted in David Pritchard, `The Encyclopedia of Chess Variants')
-
-
- "... shogi [is] by far the most complex form of chess that has ever
- achieved widespread popularity."
-
- -- R. Wayne Schmittberger, `New Rules for Classic Games'
-
-
- 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:
-
-
- 1. 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).
-
- 2. There are almost no draws (about 1-2% of all games in professional
- play).
-
- 3. Exchanges complicate the play rather than simplifying it.
-
- 4. 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.
-
- 5. 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.
-
- 6. Most importantly: it's more fun than other forms of chess :-)
-
-
-
- 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.
-
-* Menu:
-
-* The rules of shogi::
-* Sample game::
-* Mating problems::
-* Shogi variants::
-* Differences between shogi and chess::
-
-\1f
-File: gnushogi.info, Node: The rules of shogi, Next: Sample game, Prev: About shogi, Up: About shogi
-
-The rules of shogi
-==================
-
- 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 xshogi
-(*note xshogi::) and compare the starting setup there with the starting
-setup in this file (*note 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.
-
-* Menu:
-
-* The moves of the pieces::
-* The opening setup::
-* Promotion of pieces::
-* Drops::
-* Winning the game::
-* Draws::
-* Handicaps::
-* Notes for chess players::
-
-\1f
-File: gnushogi.info, Node: The moves of the pieces, Next: The opening setup, Prev: The rules of shogi, Up: The rules of shogi
-
-The moves of the pieces
------------------------
-
- 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:
-
- 1. 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.
-
- 2. 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.
-
- 3. 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.
-
- 4. 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.
-
- 5. 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.
-
- 6. 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.
-
- 7. The lance (L). A lance can move any number of squares straight
- forward. A lance promotes to a gold general.
-
- 8. 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 _en-passant_ capture. A pawn promotes to a gold
- general; a promoted pawn is usually known as a "Tokin".
-
-
-\1f
-File: gnushogi.info, Node: The opening setup, Next: Promotion of pieces, Prev: The moves of the pieces, Up: The rules of shogi
-
-The opening setup
------------------
-
- The opening setup for shogi is as follows:
-
- 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
-+--------------------------------------------+
-
-
- 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).
-
-\1f
-File: gnushogi.info, Node: Promotion of pieces, Next: Drops, Prev: The opening setup, Up: The rules of shogi
-
-Promotion of pieces
--------------------
-
- 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 (*note The moves of the pieces::) but are repeated here for
-reference:
-
-Pawn
- promotes to gold general (called a `tokin' in this case only).
-
-Lance
- promotes to gold general.
-
-Knight
- promotes to gold general.
-
-Silver general
- promotes to gold general.
-
-Gold general
- does not promote.
-
-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.
-
-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.
-
-King
- does not promote.
-
-
- 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:
-
-
- 1. You must promote a pawn or a lance after moving it to the last
- rank.
-
- 2. You must promote a knight after moving it to either of the last
- two ranks.
-
-
-
- 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 (*note Drops::) always drop in the
-unpromoted state, even if they drop into the promotion zone.
-
-\1f
-File: gnushogi.info, Node: Drops, Next: Winning the game, Prev: Promotion of pieces, Up: The rules of shogi
-
-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:
-
- 1. 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 _promoted_ pawn
- belonging to the same player, however.
-
- 2. 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 :-)
-
- 3. 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.
-
-
- 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.
-
-\1f
-File: gnushogi.info, Node: Winning the game, Next: Draws, Prev: Drops, Up: The rules of shogi
-
-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.
-
-\1f
-File: gnushogi.info, Node: Draws, Next: Handicaps, Prev: Winning the game, Up: The rules of shogi
-
-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:
-
-
- * Draws cannot be offered.
-
- * There is no fifty-move rule.
-
- * A stalemate counts as a win for the stalemater. Stated otherwise:
- if you can't move, you lose.
-
- * Perpetual check is illegal (see below).
-
-
-
- There are only two legal ways in which a draw can occur:
-
-
- 1. 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.
-
- 2. 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.
-
-
-
-\1f
-File: gnushogi.info, Node: Handicaps, Next: Notes for chess players, Prev: Draws, Up: The rules of shogi
-
-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 _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 (*note References and links::) and, I believe, represent
-current Japanese practice.
-
-
- 1. The stronger player removes his left lance (on 1a).
-
- 2. 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.
-
- 3. The stronger player removes his bishop.
-
- 4. The stronger player removes his rook.
-
- 5. The stronger player removes his rook and left lance.
-
- 6. 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.
-
- 7. The stronger player removes his rook and bishop. This is usually
- called a "two-piece" handicap.
-
- 8. The stronger player removes his rook, bishop, and both lances.
- This is called a "four-piece" handicap.
-
- 9. The stronger player removes his rook, bishop, both lances, and both
- knights. This is called a "six-piece" handicap.
-
- 10. The stronger player removes his rook, bishop, both lances, both
- knights, and both silvers. This is called an "eight-piece"
- handicap.
-
-
-
- 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.
-
-\1f
-File: gnushogi.info, Node: Notes for chess players, Prev: Handicaps, Up: The rules of shogi
-
-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.
-
-
- 1. There is no queen.
-
- 2. Pawns capture the same way they move. There is no initial
- two-space pawn move and no _en-passant_ move.
-
- 3. There is no special castling move. There _are_ a large number of
- possible defensive formations referred to as "castles" (*note
- Sample game::) but there is no need for special moves to create
- them.
-
- 4. A given piece can only promote to _one_ other kind of piece.
-
-
-
-\1f
-File: gnushogi.info, Node: Sample game, Next: Mating problems, Prev: The rules of shogi, Up: About shogi
-
-Sample game
-===========
-
- This game was annotated by Pieter Stouten (*note 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 gnushogi/xshogi 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. ]
-
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