1
This is gnushogi.info, produced by Makeinfo version 3.12h from
4
This file describes how to use GNU shogi, a program which plays
5
Shogi (Japanese chess).
7
Copyright (C) 1999 Michael C. Vanier and the Free Software
10
Permission is granted to make and distribute verbatim copies of this
11
manual provided the copyright notice and this permission notice are
12
preserved on all copies.
14
Permission is granted to copy and distribute modified versions of
15
this manual under the conditions for verbatim copying, provided that
16
the entire resulting derived work is distributed under the terms of a
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permission notice identical to this one.
19
Permission is granted to copy and distribute translations of this
20
manual into another language, under the above conditions for modified
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versions, except that this permission notice may be stated in a
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translation approved by the Free Software Foundation.
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File: gnushogi.info, Node: Top, Next: (dir), Prev: (dir), Up: (dir)
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GNU Shogi (Japanese chess)
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**************************
32
* Introduction:: What is GNU shogi?
33
* License:: The GNU General Public License.
34
* About shogi:: General information, rules, etc.
35
* gnushogi:: How to play GNU shogi (gnushogi).
36
* xshogi:: The X interface to GNU shogi.
37
* References and links:: Where to go for more information.
39
* Bugs:: Where and how to report bugs.
43
File: gnushogi.info, Node: Introduction, Next: License, Prev: Top, Up: Top
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GNU shogi is a program that plays shogi, the Japanese version of
49
chess, against a human (or computer) opponent. This file describes how
50
to use GNU shogi and also gives background information about the game
53
This file describes GNU shogi version 1.3. It was written by me,
54
Mike Vanier, the current maintainer of GNU shogi. My email address is
55
<mvanier@bbb.caltech.edu>.
57
GNU shogi is actually two programs:
61
is the text-based program which also contains the game-playing
65
is the X-windows graphical interface to gnushogi.
68
Since xshogi invokes gnushogi, most players will just type "xshogi"
71
Disclaimer: I use the personal pronouns "him", "his" etc. to refer
72
to a shogi player regardless of gender. That's easier than writing
73
"his or her" all over the place. I don't mean to infer that women
74
don't play shogi; in fact shogi is very popular in Japan among women as
78
File: gnushogi.info, Node: License, Next: About shogi, Prev: Introduction, Up: Top
80
GNU GENERAL PUBLIC LICENSE
81
**************************
85
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
86
675 Mass Ave, Cambridge, MA 02139, USA
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Everyone is permitted to copy and distribute verbatim copies
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END OF TERMS AND CONDITIONS
375
How to Apply These Terms to Your New Programs
376
=============================================
378
If you develop a new program, and you want it to be of the greatest
379
possible use to the public, the best way to achieve this is to make it
380
free software which everyone can redistribute and change under these
383
To do so, attach the following notices to the program. It is safest
384
to attach them to the start of each source file to most effectively
385
convey the exclusion of warranty; and each file should have at least
386
the "copyright" line and a pointer to where the full notice is found.
388
ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
389
Copyright (C) 19YY NAME OF AUTHOR
391
This program is free software; you can redistribute it and/or modify
392
it under the terms of the GNU General Public License as published by
393
the Free Software Foundation; either version 2 of the License, or
394
(at your option) any later version.
396
This program is distributed in the hope that it will be useful,
397
but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
399
GNU General Public License for more details.
401
You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
403
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
405
Also add information on how to contact you by electronic and paper
408
If the program is interactive, make it output a short notice like
409
this when it starts in an interactive mode:
411
Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR
412
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
414
This is free software, and you are welcome to redistribute it
415
under certain conditions; type `show c' for details.
417
The hypothetical commands `show w' and `show c' should show the
418
appropriate parts of the General Public License. Of course, the
419
commands you use may be called something other than `show w' and `show
420
c'; they could even be mouse-clicks or menu items--whatever suits your
423
You should also get your employer (if you work as a programmer) or
424
your school, if any, to sign a "copyright disclaimer" for the program,
425
if necessary. Here is a sample; alter the names:
427
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
428
`Gnomovision' (which makes passes at compilers) written by James Hacker.
430
SIGNATURE OF TY COON, 1 April 1989
431
Ty Coon, President of Vice
433
This General Public License does not permit incorporating your
434
program into proprietary programs. If your program is a subroutine
435
library, you may consider it more useful to permit linking proprietary
436
applications with the library. If this is what you want to do, use the
437
GNU Library General Public License instead of this License.
440
File: gnushogi.info, Node: About shogi, Next: gnushogi, Prev: License, Up: Top
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About the game of shogi
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***********************
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"Japanese chess cedes nothing in depth or beauty to the European
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game... it is at least as interesting."
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-- Alexander Alekhine
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(quoted in David Pritchard, `The Encyclopedia of Chess Variants')
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"... shogi [is] by far the most complex form of chess that has ever
453
achieved widespread popularity."
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-- R. Wayne Schmittberger, `New Rules for Classic Games'
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Shogi is the version of chess played in Japan. It is strikingly
459
different from standard chess (which I shall refer to henceforth as
460
"international chess") and also to all other regional variants, because
461
captured pieces can re-enter play on the side of the capturer. This
462
has several interesting effects on the play of the game:
465
1. Shogi is much more complex than international chess, at least in
466
terms of the average number of possible moves per turn (estimated
467
at about 35 for chess and at about 80 for shogi).
469
2. There are almost no draws (about 1-2% of all games in professional
472
3. Exchanges complicate the play rather than simplifying it.
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4. There are no "endgames" in the standard chess sense; all pieces
475
remain in play throughout the game. Games typically end in a race
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to checkmate the other player before being checkmated oneself.
478
5. Ownership of a piece is not indicated by the color of the piece;
479
instead, pieces are wedge-shaped and point towards the opponent.
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The name of the piece is inscribed in Kanji characters on the
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6. Most importantly: it's more fun than other forms of chess :-)
487
Shogi is extremely popular in Japan; it has been estimated that 20
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million Japanese can play shogi, of which perhaps 1 million are active
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players. It is even more popular there than the game of go, Japan's
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other favorite board game. There are a number of professional players
491
who make a considerable amount of money playing in shogi tournaments,
492
and the game receives extensive newpaper and television coverage.
493
Despite this, the game has yet to become popular outside of Japan. Part
494
of this is because the Kanji characters on the pieces scare away some
495
people, but mostly it's due, I think, to lack of exposure to the game
496
and to the difficulty of finding opponents. I hope that GNU shogi will
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help introduce shogi to a wider audience.
501
* The rules of shogi::
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* Differences between shogi and chess::
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File: gnushogi.info, Node: The rules of shogi, Next: Sample game, Prev: About shogi, Up: About shogi
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Shogi is a two-person abstract strategy board game with full
514
information (i.e. all pieces and moves are visible to both players at
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all times). It is in the chess family, being descended from the same
516
ancestral game as international chess: the Indian game of Chaturanga.
517
The two players are referred to as "Black" and "White", with Black
518
moving first (unlike in international chess, where White moves first),
519
and with movement alternating between the two players. Note that
520
"Black" and "White" are just names; the pieces are not colored.
521
Instead, they are flat, wedge-shaped pieces which point towards the
522
opponent. The identity of a given piece is indicated by two Japanese
523
Kanji characters on each piece. In fact, only the top character is
524
needed to identify the piece and thus only the top character is used in
525
shogi diagrams. I will use alphabetical equivalents in the diagrams
526
here; to see what the Kanji characters look like, start up xshogi
527
(*note xshogi::.) and compare the starting setup there with the
528
starting setup in this file (*note The opening setup::.).
530
The object of the game is to capture the opponent's King. The board
531
is a grid of 9x9 uncolored squares, and pieces are placed on the
532
squares. Each player begins with 20 pieces, described in the next
533
section. Capture is by displacement, as in international chess.
537
* The moves of the pieces::
538
* The opening setup::
539
* Promotion of pieces::
544
* Notes for chess players::
547
File: gnushogi.info, Node: The moves of the pieces, Next: The opening setup, Prev: The rules of shogi, Up: The rules of shogi
549
The moves of the pieces
550
-----------------------
552
Each player at the beginning of a shogi game has a total of 20
553
pieces of eight different types. The moves of the shogi pieces can be
554
divided into three classes: "stepping" pieces, that only move one
555
square at a time; "ranging" pieces that move any number of unobstructed
556
squares in a line, and "jumping" pieces that can jump over obstructing
557
pieces to reach their destination squares. Most pieces can also
558
promote to different (usually stronger) pieces under certain
559
circumstances (see the next section). All pieces capture the same way
560
that they move (even pawns). The piece moves and promotions are as
561
follows; each piece name is followed by the standard piece abbreviation:
563
1. The king (K). The king can move one square in any horizontal,
564
vertical, or diagonal direction, just like the king in
565
international chess. The king does not promote.
567
2. The rook (R). The rook can move any number of squares in a
568
horizontal or vertical direction. The rook is the same as the
569
rook in international chess (except that it can promote). A rook
570
promotes to a "dragon king" or "dragon" for short (often just
571
referred to as a "promoted rook"), which can move as a rook or can
572
move one square in any diagonal direction.
574
3. The bishop (B). The bishop can move any number of squares in a
575
diagonal direction. The bishop is the same as the bishop in
576
international chess (except that it can promote). A bishop
577
promotes to a "dragon horse" or "horse" for short (often just
578
referred to as a "promoted bishop"), which can move as a bishop or
579
can move one square in any horizontal or vertical direction.
580
Note: the horse should not be confused with a knight (see below),
581
as they are two completely different pieces.
583
4. The gold general (G). A gold general can move one square in any
584
horizontal or vertical direction, or one square in a forward
585
diagonal direction. Gold generals do not promote.
587
5. The silver general (S). A silver general can move one square in
588
any diagonal direction, or one square straight forward. A silver
589
general promotes to a gold general.
591
6. The knight (N). A knight can move one square straight forward
592
followed by one square to either forward diagonal, jumping over
593
intervening pieces if any. In other words, a knight moves like
594
its international chess counterpart, but forward only. A knight
595
promotes to a gold general. The knight is the only jumping piece,
598
7. The lance (L). A lance can move any number of squares straight
599
forward. A lance promotes to a gold general.
601
8. The pawn (P). A pawn can move one square straight forward. The
602
pawn captures the same way that it moves, in contrast to
603
international chess. There is also no initial two-space move for
604
pawns and no _en-passant_ capture. A pawn promotes to a gold
605
general; a promoted pawn is usually known as a "Tokin".
609
File: gnushogi.info, Node: The opening setup, Next: Promotion of pieces, Prev: The moves of the pieces, Up: The rules of shogi
614
The opening setup for shogi is as follows:
617
+--------------------------------------------+
618
| wL | wN | wS | wG | wK | wG | wS | wN | wL | a
619
+--------------------------------------------+
620
| | wR | | | | | | wB | | b
621
+--------------------------------------------+
622
| wP | wP | wP | wP | wP | wP | wP | wP | wP | c
623
+--------------------------------------------+
624
| | | | | | | | | | d
625
+--------------------------------------------+
626
| | | | | | | | | | e
627
+--------------------------------------------+
628
| | | | | | | | | | f
629
+--------------------------------------------+
630
| bP | bP | bP | bP | bP | bP | bP | bP | bP | g
631
+--------------------------------------------+
632
| | bB | | | | | | bR | | h
633
+--------------------------------------------+
634
| bL | bN | bS | bG | bK | bG | bS | bN | bL | i
635
+--------------------------------------------+
638
Here, "b" stands for "black" and "w" stands for "white", so that,
639
for instance, "bL" means "black lance". The numbers above the files
640
and the letters to the right of the ranks represent the most common
641
notation system used for shogi by westerners (the Japanese also use
642
Arabic numerals for the files but use Japanese numerals for the ranks).
645
File: gnushogi.info, Node: Promotion of pieces, Next: Drops, Prev: The opening setup, Up: The rules of shogi
650
In sharp contrast to international chess, where only pawns can
651
promote to higher-ranked pieces, most of the pieces in shogi can
652
promote. The promoted ranks are discussed in the section on piece
653
moves (*note The moves of the pieces::.) but are repeated here for
657
promotes to gold general (called a `tokin' in this case only).
660
promotes to gold general.
663
promotes to gold general.
666
promotes to gold general.
672
promotes to "dragon horse" or just "horse" for short. The horse
673
can move as a bishop or can move one square in any orthogonal
677
promotes to "dragon king" or just "dragon" for short. The dragon
678
can move as a rook or can move one square in any diagonal
685
The three ranks furthest away from each player constitute his/her
686
"promotion zone". A player may, but is not required to, promote a
687
piece after making a move in which the piece begins and/or ends in the
688
promotion zone. Thus you can promote a piece when moving the piece into
689
the promotion zone, out of the promotion zone, or entirely within the
690
promotion zone. Promotion is mandatory in these cases:
693
1. You must promote a pawn or a lance after moving it to the last
696
2. You must promote a knight after moving it to either of the last
701
These forced promotions ensure that a piece cannot be moved to a
702
square from which it would have no further move.
704
Pieces "dropped" onto the board (*note Drops::.) always drop in the
705
unpromoted state, even if they drop into the promotion zone.
708
File: gnushogi.info, Node: Drops, Next: Winning the game, Prev: Promotion of pieces, Up: The rules of shogi
713
When a player captures a piece, that piece is not removed from play.
714
Instead, it becomes the property of the capturer and can re-enter play
715
by being placed on (almost) any vacant square during the player's move.
716
This is known as a "drop" and counts as a full move (in other words,
717
you can either move a piece on the board or drop a piece onto the board
718
during your move, but not both). All pieces drop in the unpromoted
719
state. Pieces may be legally dropped in their promotion zone, but they
720
do not promote on that turn.
722
There are several restrictions on drops:
724
1. A pawn may not be dropped onto a file if there is already an
725
unpromoted pawn belonging to the same player on that file. It is
726
legal to drop a pawn on a file which contains a _promoted_ pawn
727
belonging to the same player, however.
729
2. A pawn may not be dropped to give immediate checkmate on the move.
730
A pawn is, however, permitted to be moved on the board to give
731
immediate checkmate. This is a curious rule, and if anyone knows
732
the reason for it I would appreciate it if they would contact me
733
and explain it to me :-)
735
3. A pawn or piece may not be dropped onto a square from which they
736
would have no legal move. This means that pawns and lances may
737
not be dropped onto the last rank, and the knight may not be
738
dropped onto the last or second-to-last rank.
741
It is entirely permissible (and often advisable) to drop a piece or
742
pawn between one's King and an attacking ranging piece. For this
743
reason, the final checkmating move is nearly always an attack on the
744
King from an adjacent square (except for an attack by a Knight).
746
Captured pieces are said to be pieces "in hand".
748
The drop is the primary distinguishing feature of Japanese chess,
749
shared with no other popular chess-type game. It gives shogi a very
750
aggressive quality, and dramatically increases the number of possible
751
moves once a few pieces have been captured. Another interesting
752
feature of shogi is that exchanges complicate play rather than
753
simplifying it (as in international chess), because of the drop rule.
756
File: gnushogi.info, Node: Winning the game, Next: Draws, Prev: Drops, Up: The rules of shogi
761
A game of shogi is won by capturing the opponent's king. In general,
762
this is done by checkmating the king: attacking the king in such a way
763
that the king cannot be defended no matter what the defending player
764
moves. Note, though, that there is no rule that requires a player to
765
defend a king which is being attacked. However, if he does not defend
766
his king, the opponent is entirely free to capture it on the next move,
767
thus winning the game. As in international chess, in practice most
768
games end by resignation when one player realizes that he cannot escape
772
File: gnushogi.info, Node: Draws, Next: Handicaps, Prev: Winning the game, Up: The rules of shogi
777
There are very few draws in shogi; only about 1-2% of professional
778
games end in a draw. One reason for this is that material can never be
779
depleted as in chess, because captured pieces are constantly re-entering
780
play as a consequence of the drop rule. In fact, most of the ways a
781
game can be drawn in chess are not allowed in shogi:
784
* Draws cannot be offered.
786
* There is no fifty-move rule.
788
* A stalemate counts as a win for the stalemater. Stated otherwise:
789
if you can't move, you lose.
791
* Perpetual check is illegal (see below).
795
There are only two legal ways in which a draw can occur:
798
1. A position (including the pieces in hand) occurs 4 times with the
799
same player to move (called "Sennichite"). However, if this is
800
caused by consecutive checks (direct attacks on the King,
801
threatening to capture it on the next move) by one side, the
802
player giving these checks loses the game. In other words,
803
perpetual check results in a loss for the attacker who recreates
804
the same position the 4th time.
806
2. Both players have moved their King into the the promotion zone (or
807
they cannot be prevented from doing so) and the Kings cannot be
808
checkmated. A King who has entered the promotion zone is known as
809
an "entering King"; due to the forward orientation of most shogi
810
pieces, it is very hard to mate such a King. In that case the
811
players may decide to count their pieces as follows: the King does
812
not count, the Rook and Bishop count as 5 points, and all other
813
pieces as one point. Promotion is disregarded. If both players
814
have at least 24 points the game is a draw (called "Jishogi"). If
815
a player has less, he loses the game.
817
Of course, a player can refuse to count pieces when he still has
818
mating chances or chances to gain material which would affect the
819
outcome of the counting. There is no strict rule about what to do
820
if this is not the case, but nonetheless a player refuses to count
821
up (e.g. because he does not have enough points for a draw). It
822
has been generally accepted that in such a case the game ends and
823
the pieces are counted after one player has managed to get all his
824
pieces protected in the promotion zone.
829
File: gnushogi.info, Node: Handicaps, Next: Notes for chess players, Prev: Draws, Up: The rules of shogi
834
Unlike international chess, shogi has a well-established handicap
835
system which is used when players of different strengths play against
836
each other. Handicaps range from small to huge, which makes it
837
possible for weak players to play against even very strong players and
838
have an even chance of winning.
840
Shogi players are ranked as follows: the weakest rank is around 15
841
"kyu", which represents a beginner. 14 kyu is higher than 15 kyu, 13
842
kyu is higher still, and so on until you get to 1 kyu. The next highest
843
rank is 1 "dan", followed by 2 dan, 3 dan and so forth. The highest
844
amateur rank is 6 dan; professionals go up to 9 dan. However,
845
professional ranks are not the same as amateur ranks; a professional 1
846
dan is _much_ stronger than an amateur 1 dan. This system is similar
847
to that used by go players (and also other Japanese sports such as
850
A handicap consists of the stronger player playing White and removing
851
one or more pieces from his side of the board at the start of the game.
852
These pieces are permanently removed from play; they are not in hand.
854
The following is a list of the accepted handicaps, from weakest to
855
strongest. The degree of the handicap, represented by the position in
856
the list, represents the difference in rank between the two players for
857
which the handicap is appropriate. These rules are taken from the books
858
"Shogi for Beginners" by John Fairbairn and "The Art of Shogi" by Tony
859
Hoskings (*note References and links::.) and, I believe, represent
860
current Japanese practice.
863
1. The stronger player removes his left lance (on 1a).
865
2. The players play a two-game match; in the first game the stronger
866
player removes his left lance (on 1a), while in the second game he
869
3. The stronger player removes his bishop.
871
4. The stronger player removes his rook.
873
5. The stronger player removes his rook and left lance.
875
6. The players play a two-game match; in the first game the stronger
876
player removes his rook and left lance (on 1a), while in the
877
second game he removes his rook and bishop.
879
7. The stronger player removes his rook and bishop. This is usually
880
called a "two-piece" handicap.
882
8. The stronger player removes his rook, bishop, and both lances.
883
This is called a "four-piece" handicap.
885
9. The stronger player removes his rook, bishop, both lances, and both
886
knights. This is called a "six-piece" handicap.
888
10. The stronger player removes his rook, bishop, both lances, both
889
knights, and both silvers. This is called an "eight-piece"
894
Another advantage of playing handicap games is that the handicaps
895
alter the optimal strategy for both players. For instance, handicaps
896
all have their own opening lines which may bear little or no
897
resemblance to those used in non-handicap shogi. This means that when
898
learning handicap shogi, you are essentially learning completely new
899
games which use the same equipment!
901
The reader may wonder how on earth a player giving an eight-piece
902
handicap, say, could possibly hope to win. Don't forget, though, that
903
in shogi the opponent's pieces can be captured and then become part of
904
one's own army. Thus, if the opponent plays badly enough, the number of
905
pieces will soon even out.
908
File: gnushogi.info, Node: Notes for chess players, Prev: Handicaps, Up: The rules of shogi
910
Notes for chess players
911
-----------------------
913
Here are a few miscellaneous things that may confuse chess players.
914
Some of these have been mentioned elsewhere, but they bear repeating.
917
1. There is no queen.
919
2. Pawns capture the same way they move. There is no initial
920
two-space pawn move and no _en-passant_ move.
922
3. There is no special castling move. There _are_ a large number of
923
possible defensive formations referred to as "castles" (*note
924
Sample game::.) but there is no need for special moves to create
927
4. A given piece can only promote to _one_ other kind of piece.
932
File: gnushogi.info, Node: Sample game, Next: Mating problems, Prev: The rules of shogi, Up: About shogi
937
This game was annotated by Pieter Stouten (*note References and
938
links::.). I have made some minor corrections. Note that captures are
939
denoted by the "x" symbol e.g. Rx3f and drops are denoted by the "*"
940
symbol e.g. R*3f. Check is indicated by a "+" after the move, e.g.
941
R3f+. I recommend you use gnushogi/xshogi to play along with this
942
game. In xshogi simply hit the "Force Moves" button after starting up,
943
while in gnushogi enter the word "force" at the prompt. This will
944
allow you to enter moves for both sides.
946
Note also that the move numbering system used here is the chess-type
947
system where one move means one move by each player. The Japanese count
948
one move made by each player as two moves.
950
--------------------------------------------------------------------------
952
Below you will find (the English translation of) an annotated game
953
which was published in the Dutch Shogi magazine "81" and in the Dutch
954
beginners booklet. It has proven to be a very useful game to explain
955
some basic principles of Shogi. Also, it is a rather straightforward
956
game compared to professional games where in most cases very diffuse
957
middle game fights take place.
959
Pieter Stouten, 14th May 1990.
961
--------------------------------------------------------------------------
963
Black: Michael Trent (1-dan). White: David Murphy (2-dan).
965
1. P2f P3d 2. P2e B3c
966
[ This move is necessary, as otherwise white can exchange pawns: 3. P2d
967
Px2d 4. Rx2d. He would thus get a pawn in hand and open up his rook
971
[ White closes the bishop diagonal again. He plans to play ranging rook
972
(the rook goes to 5b, 4b, 3 or 2b; a defensive strategy) and in that
973
case he'd better avoid an exchange of bishops. One of the reasons is
974
that he will have problems developing his pieces without leaving holes
977
4. S4h R3b 5. P3f S4b 6. K6h K6b
978
[ In general the rook plays an important role in the attacks. It is
979
wise to move the king away from the area where the initial fights will
980
be and both players act according to the Shogi proverb "keep the rook
983
7. K7h K7b 8. P5f P5d 9. G4i-5h G4a-5b
984
[ Both players use their second gold general to build their castle. ]
987
[ In itself this move is not bad. However, it will become clear that
988
black plans a quick attack and in that case it is wiser to omit this
991
10... S5c 11. P1f P1d
992
[ The advance of the edge pawns must be timed very well. The remark at
993
black's tenth move applies here too: this move is good if black wants to
994
play a slow game, because it eliminates a future B1e. ]
996
12. P4f K8b 13. N3g S7b
997
[ Black develops his knight in order to start an attack over the second,
998
third and fourth files. White strengthens his king's position and
999
awaits the attack. He aims at a counterattack as soon as black has
1000
broken through into the white camp. Probably white's breakthrough will
1001
take place later, but he has good compensation in the form of a stronger
1002
castle. This theme occurs very often in static rook versus ranging rook
1006
[ Black starts his attack and white puts up a very passive defence. His
1007
rook has a hard task now to penetrate the black position. Moreover, he
1008
blocks his own bishop. It seems much better to start a counterattack
1009
with 14... P3e, later to be followed by B2b, B5a or Bx4d in order to use
1010
his rook more actively. ]
1012
15. Px4d Sx4d 16. P*4e S5c
1013
[ 16... Sx4e is more active. A silver general is normally more valuable
1014
than a knight, but white gets two pawns in hand and black none, while
1015
the knight might come in handy for white too. ]
1017
17. Bx3c+ Nx3c 18. P2d Px2d
1018
[ Black threatens to break through and white has to consider taking the
1019
pawn on 2d or starting a counterattack with Nx4e. If he chooses the
1020
latter, black can play Px2c+ followed by +P3c. The disadvantage is the
1021
black "tokin" (=promoted pawn) that white will get in his camp; the
1022
advantage is that it will cost black two more moves to promote his rook.
1023
Because white did not trust that the result after engaging in a
1024
"semeai" (=mutual attack) with 18...Nx4e would give a positive result,
1025
he captured the pawn on 2d. Making the right decision in moments like
1026
this often makes the difference between a win and a loss: miss one
1027
attacking chance and you will be forced to defend the whole game until
1028
the unavoidable defeat; on the other hand, an unsound attack can destroy
1029
all "aji" (=potential, meaning possibilities, threats) without getting
1030
anything in return. ]
1032
19. Rx2d Nx4e 20. Nx4e Rx4e 21. R2a+ P*4g
1033
[ Now it becomes clear why black's 10. S6h was not good. Had this move
1034
been omitted, then white would not have had the time to play 13... S7b
1035
and after R2a+ the gold on 6a would hang. Thus black would have kept
1036
"sente" (=initiative). Instead of 21... P*4g, B*6d is a very good
1037
move, because after 22. P*2h black does not have a pawn in hand anymore
1038
and he is being threatened with the annoying 22... N*4f 23. G5g N3h+
1039
24. S4g +N4h also. Black can also counter 21... B*6d with 22. N*3g.
1040
White would then reply with 22... R4b 23. B*3c P*4g 24. Bx4b+ Sx4b. The
1041
white rook has played its role and instead of spending moves on saving
1042
it white starts to scatter black's defences by successive pawn drops on
1043
the fourth file: 25. Gx4g P*4f 26. G5g N*6e 27. G5h P4g+ 28. Gx4g P*4f.
1044
This analysis was provided by Kato Hifumi, 9-dan professional (the
1045
highest regular grade). Destroying the coherence of the enemy pieces
1046
(their shape) by dropping pawns is one of the most important Shogi
1047
techniques. With the actual move 21... P*4g white missed a good
1050
22. Sx4g P*4f 23. B*3g Px4g+ 24. +Rx6a +Px3g
1051
[ 23. B*3g seems pointless, but a closer look reveals that it is
1052
actually quite mean. On move 24 white cannot capture black's "Ryu"
1053
(=dragon =promoted rook) with his silver: 24... Sx6a 25. N*7d K7b 26.
1054
G*8b mate. By attacking the front of the white castle and threatening
1055
to mate him there, black has the chance to break down the white
1056
defences from the side. ]
1059
[ Here 25... B*4d would be much better, because it is defensive and
1060
attacking at the same time. After e.g. 26. G*4c Bx9i+ 27. Gx5c black
1061
threatens 28. +Rx7b Kx7b 29. S*6a K8b 30. S*7a Kx7a 31. G*7b mate.
1062
White is one move quicker, however. He has the following beautiful
1063
"tsume" (mating sequence where every move is check): 27... N*8f 28. Px8f
1064
S*8g 29. Kx8g B*9h 30. K7h Bx8i+ 31. K8g +B8i-8h 32. K9f L*9e mate.
1065
This illustrates the sharpness of Shogi: one move can make the
1066
difference between winning and losing. ]
1069
[ This move eliminates white's last chances. 26... R4b 27. +Rx4b Sx4b
1070
28. R*4a seems annoying, but after 28... B*3c 29. S7g B*3b white wins
1071
the rook and with his "tokin" on 3g there still is some hope. ]
1074
[ White cannot defend anymore, so he starts a desperate attack. Black
1075
does not lose the right track, however. ]
1077
28. Nx5c+ +Px5h 29. +Nx6b +Px6h 30. Gx6h N*8f 31. Px8f B*6i 32.
1078
Gx6i R4h+ 33. N*6h +Rx6h 34. Gx6h S*8g 35. Kx8g N*9e 36. K7h
1080
[ White resigns here, because after 36... B*8g 27. K7g his attack has
added
removed
doc/gnushogi.info-1
