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#Post#: 545--------------------------------------------------
Tenjiku Shogi opening theory
By: HGMuller Date: March 7, 2018, 9:41 am
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The historic Japanes game Tenjiku Shogi is one of the most
violent Chess games ever conceived. It features 'Fire Demons',
which do not only capture what is on the square they land, but
'burn' every enemy on the 8 adjacent squares as well. Somewhat
like Atomic Chess, except that they do not explode themselves
(or any friendly piece), so they can keep doing it turn after
turn. And it even does it in the opponent's turn as well; moves
that land adjacent to an enemy Fire Demon make the moved piece
evaporate without a trace. (Even a Fire Demon itself evaporates
this way, without burning anything.)
Apart from that the Fire Demon is an enormously mobile piece. It
moves as a Queen, except along one of the orthogonals. (There is
some controversy whether this would be sideway or vertical.) And
in addition it can make up to 3 King steps, allowing it to sneak
through holes in the enemy lines and around corners. (But must
stop on a capture, i.e. when it reaches a square that was
occupied.) This gives it 30 extra move targets not reachable by
the Queen moves, many of them more difficult to block, as they
can be reached through more than one path.
Unlike most Shogi variants, the opening phase of Tenjiku Shogi
is extremely tactical. At least with the rules that modern
players use, where another class of exceptional pieces (the
'jumping generals) can deliver check. (Whether the historic
rules allowed this is also controversial.) These pieces can jump
over arbitrary many other pieces when capturing, so they are
practically unblockable (except by each other). The problem is
that in the initial position the King is completely smothered,
so any (safe) check would be a mate. So not to get checkmated is
a major problem, starting from move 1: the most popular opening
move immediately threatens mat in 1.
No information has survived from historic times about strategy
and opening theory. The historic manuscripts only contain a rule
description. So modern players have to discover the critical
opening theory all by themselves. I wonder if this forum would
be a good place to discuss Tenjiku Shogi opening theory.
#Post#: 601--------------------------------------------------
Re: Tenjiku Shogi opening theory
By: HGMuller Date: March 14, 2018, 2:35 am
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Let me start with a diagram of the initial position, using
'mnemonic' piece icons. This makes the way most pieces move
trivially recognizable from their pictogram: virtually all
pieces only slide along principal rays (like a Queen), with
infinite range, or just one or two steps. (Or not at all.)
Pieces that only step are depicted as a small square, with
'bites' taken out of it in the directions they cannot step. If
they move more than a single step in a certain direction, they
bulge out of that square. A radial line then indicates infinite
range, otherwise the range was two.
[img]
HTML http://hgm.nubati.net/tenjiku/ten.PNG[/img]
Only few pieces have moves more complex than can be indicated by
this system, and have special icons. Of notable importance are
the (2x) 6 pieces depicted as circles. These are the 'jumping
generals' (Great General, Vice General, Rook General and Bishop
General), which can jump over an arbitrary number of pieces when
capturing. Otherwise their move is as their name (and the radial
striping pattern on their icon) suggests. The VG in addition can
also make up to 3 King steps in arbitrary directions. The
sliding capture moves of these generals cannot be blocked by
normal pieces (they can block each other according to some
hierarchy, however). So they pose a very large danger to the
King, for inflicting a smothered mate.
The dominant piece is the Fire Demon, depicted as a candle
flame. It 'burns' all adjacent enemy pieces, and thus can
capture up to 8 victims in a single move. In 21st-Century
Tenjiku it moves like a Queen except sideways, in addition to be
able to take up to 3 independently chosen King steps. Tenjiku
openings start with an 'aireal fight', where the jumping
generals and Fire Demons roam the board, the other pieces being
hardly touched at all. Unlike in Chess, multiple moves with the
same piece is common practice.
The most popular opening move is 1. P-j6, to open a hole for the
VG to move out. (We use standard board coordinates here, where
a1 is the lower-left corner.) This immediately threatens a
smothered mate through 2. VG-o10. The Kirin on j15 is the only
piece adjacent to the King that can be moved in the initial
position, to create some breathing space. But as this happens to
be on the check diagonal, it would not prevent the mate. So
black must cover the checking square o10 to prevent the mate.
There are only two moves that do this: 1... SE-n11 and 1...
P-o11.
Now 1... P-o11 does not work, and gets black mated in 3 anyway:
2. VG-n9 {now threatens mate on p9} SE-n11 {the only way to
cover p9} 3. VG-p9 SExp9 4. BGxp9#. So 1... SE-n11 is a forced
move. This is then usually followed by 2. BG-i6 to mount an
attack on the SE that is critical in preventing the mate.
(Threat: 3. BGxn11 {check} Pxn11 {only evasion} 4. VG-011#.)
There are several ways to make sure the protection of o11 can be
maintained. For one, the Soaring Eagle protecting it can be
moves out of the BG's attack, 2... SE-p11 or 2... SE-p9. In
addition, the SE can be protected by a Water Buffalo by moving
up the intervening Pawn, 2... P-m11, so that after 3. BGxn11
WBxn11 the square o10 stays protected (by the WB).
Before discussing the merits of each of these defenses, we note
that white's first two moves can be mate threats, which can be
countered only by comparatively passive moves, which don't do
much for black's development. For white, however, this has
cleared a path for its Fire Demon to develop. E.g. through 3.
FD-k6 (the 'Quick Attack'). As the Fire Demon has an enormous
destructive potential, its early development can give a huge
advantage. Black's moves for preventing the mate did not help
develop its FD in any way. So it seems white has a huge
initial-move advantage.
The Quick Attack
This is largely illusory, however. Because on the other wing the
situation is still just as it was initially. So once the
mate-in-1 and checks-only mate threats are dealt with, black can
simply mirror white's play, making his own mate threats during
development of his Demon, forcing some passive defensive moves
on white: 3... P-g11 4. SE-c6 BG-h11 5. P-d6 FD-f11. This
restores the symmetry, and thus keeps the white advantage
limited to the original one of having the move.
#Post#: 607--------------------------------------------------
Re: Tenjiku Shogi opening theory
By: chilipepper Date: March 14, 2018, 6:53 pm
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[quote author=HGMuller link=topic=81.msg545#msg545
date=1520437317]
(There is some controversy whether this would be sideway or
vertical.)
[/quote]
Do you mean it's not clear what the original rules are? I wonder
if the rules can be "backwards-engineered" by learning which
rule creates the better play. Of course, that would only work if
the game was already played and studied enough so that it was
already optimized for the most tactical style of play (assuming
that was even the goal).
[quote author=HGMuller link=topic=81.msg545#msg545
date=1520437317]
So modern players have to discover the critical opening theory
all by themselves.
[/quote]
I suppose this is true based on the premise that it's played
less now, than it was in the past, and that nobody has analyzed
it yet with computers (which I would assume is true)?
Thanks for sharing this info. Interesting! :)
#Post#: 609--------------------------------------------------
Re: Tenjiku Shogi opening theory
By: HGMuller Date: March 15, 2018, 4:07 am
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Indeed, the historic rules are not very precisely defined. There
are only two historic manuscripts that mention the game, and I
don't have access to the raw data. (Which might not be very
helpful anyway, as it would be in archaic Japanese, in
non-machine-readable form, and I don't read Japanese at all.)
The controversy on the direction of the Demon move might be
because of a discrepancy between the verbal discription and a
drawing in the same manuscript.
People have been trying computer analysis for decades, but only
since last year I have a program that can search deep enough to
make this meaningful. Much of what I plan to post here is based
on analysis with this program. (At the moment set to use the
rules commonly used by modern players.)
Rule unclarities that would hugely affect the game are:
1) Whether the jumping generals are allowed to capture the
generals they are not allowed to jump over. (This seems standard
behavior in Chess; e.g. Rooks cannot jump over enemy pieces, but
they have no problem capturing them. So it is not clear why this
has become an issue.)
2) Whether jumping generals are allowed to capture the King. The
rules mention the King in the hierarchy of pieces that could not
be jumped over, but who would want to jump over a King if he
could capture it? It would become a totally different game if
the generals could not inflict smothered mates.
3) Wether the Fire Demon moves along files or along ranks. The
forward forking power when it moves along files (in addition to
diagonally) is extrordinary large, giving an unfair advantage to
the side that manages to develop its Demon first. (I.e. huge
first-move advantage.)
4) Whether a Water Buffalo, when it promotes to Fire Demon,
already burns away the adjacent enemies during its promotion
move. Modern rules assume this is not the case, for no clear
reason, and at the price of rule inconsistency for what happens
later. (Pieces would remain standing next to the Demon, while
new pieces landing there would evaporate.) With instant burning
the Water Buffalo would become 'nuclear tipped', and a much more
dangerous piece, as you could just run it into a dense crowd in
the enemy camp to annihilate 4 or 5 Queen-class opponents, not
caring much about the recapture.
#Post#: 718--------------------------------------------------
Re: Tenjiku Shogi opening theory
By: HGMuller Date: March 31, 2018, 12:16 pm
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Demon attack spots
Before discussing actual opening lines, let us take a look to
some general principles. E.g. why is it so important and
advantageous to develop your Fire Demon quickly?
The initial position has a fair number of weak spots for
Fire-Demon attack. The Pawns on c12 and n12 are protected in the
normal sense, but not protected against capture by a Fire Demon,
which would burn all protectors with it. (This sometimes also
works the other way around; a piece can be unprotected because
distant sliding protectors are blocked by an adjacent piece, and
a Demon would burn that adjacent piece.) These Pawns can be
protected by moving Bb15 or Bo15, respectively.
All other Pawns are protected against Demon capture. As a Demon
is 'priceless' (it would win against almost any combination of
non-Demon material), this seems to make the starting position
resistant to Demon attack, no matter how much material there was
behind the Pawn that would be burned together with it;
recapturing the Demon would always be enough compensation. There
are tactical complications, however. The Rook Generals aim at
the opposing Demons, but block each other from reaching those.
If, however, one of the Rook Generals gets burned, this
activates the RG attack on the Demon behind it, which could now
be traded for a single RG. So after the initial burn you get
immediately in a position where both Demons are under attack.
This doesn't help if the defending player can use his Demon to
capture yours, and this will move him out of the RG's path. But
after a capture/burn on the Pawns in the RG file (g12 or j12),
the RG does not only attack the defending Demon, but it protects
its own. So whether you recapture FD x FD, or recapture the FD
with another piece and leave your FD where it is, in both cases
you will get RG x FD. Of course you can then recapture that RG,
but it means you get only a single RG, while the initial burn
might have destroyed three of your jumping generals (GG + RG +
BG or VG + RG + BG). A very bad deal.
A similar case occurs on a Demon capture/burn on the Pawn in
front of the Vice General (h12). This burns GG + VG + RG, the
latter exposing the FD to RG capture, while the attacking Demon
is protected to its own GG. This would thus gain a VG + RG. The
common method to protect yourself against capture on g12, h12 or
j12 is trading the RG which is going to get burnt for the
opposing RG, even if the latter resides next to a Demon so that
it evaporates as a side effect (and thus loses you a tempo).
Then your Demon would not get under attack from the initial
burn, so you can safely recapture the attacking Demon with
another piece, (e.g. LH or FE), even if it is protected.
Even after such a defensive RG trade, a capture/burn on h12 can
still be attractive, because lacking a GG early in the game,
when the King is still suffocated amongst its own pieces, can
cause big problems. The surviving GG could check from i4, after
the VG normally standing there has evacuated that square. Which
it often can do with a check. If that is the case there is
burning of the GG causes an immediate mate-in-2 threat. Making
an 'air hole' for the King on j15 by moving away the Kirin often
does not help, because the GG, after checking on i4, can
diagonally check on o10, covering both the original King square
and the escape square. Or because a RG can assist to cover it.
In that case the only way to prevent the mate would be to make
sure you can burn a checking GG or RG on i4, for which your
Demon has to come out. So that you have to recapture after an
h12 burn with a Demon to not get mated. After which that Demon
is again traded for a single GG.
Even in if the defending side does not have to recapture your
protected Demon after burning the opponent's GG + VG, the latter
can be an attractive deal. Provided that you can force the
opponent to sac its Demon back. Burning a checking GG on i4
might be the only way to prevent checkmate after he loses the
ability to block it. And you might be able to reduce the damage
done by that to a single GG, or GG plus one other jumping
general, while your original burn destroyed more generals.
So there are in fact many places where you could slam a Demon
into the Pawn wall to gain significant material. And a Demon has
great forking power, with its three forward-directed sliding
moves. One such sliding threat might be blockable by moving up a
Pawn, but if the Demon attacks multiple vulnarable spots there
is just no defense. If the Demon can approach your Pawn rank to
within the range of its area move, he even attacks 7 Pawns at
once, most of those through multiple paths (so that blocking is
out of the question). Manoeuvring with the Demon to get a good
shot at a profitable burn is therefore the major theme of all
openings in Tenjiku Shogi.
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