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#Post#: 352--------------------------------------------------
Peace Chess (Paco Shako)
By: HGMuller Date: February 2, 2018, 7:03 am
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Rules
One of the most innovative Chess variants I ever encountered is
the recently invented 'Peace Chess
HTML http://www.pacosako.com
'. This variant has changed the general
rules for capture, which in orthodox Chess symbolizes a fight in
which the attacked piece dies, to a peaceful coexistence of the
two pieces on the target square, embracing each other. Of course
this prompts the question how to handle such embracing pairs in
the remainder of the game: what happens if a third piece now
'captures' to a square already occupied by an embracing pair?
The rules specify that in that case the third piece entering the
square replaces the piece of the same color in the embrace, and
the replaced piece then has then to move away in the same turn.
Such a released piece can do everything a lone piece could have
done, in particular it can again release pieces from another
embrace, which then has to move away, etc. So you can get
arbitrarily long chains of moves in a single turn.
The embracing pairs can also be moved, as their component
pieces, except that they can only move to empty squares. This
means both players can move them, but if (say) a white Queen is
embracing a black Knight, white can move the pair as a Queen,
and black can move it as a Knight. In all cases they would move
as a pair: the Queen would drag the Knight along, the Knight
would drag the Queen along. So there is no way to break an
embrace once it is formed, although you can substitute one piece
in the embrace for another.
He who first embraces the opponent King wins the game. As all
pieces always stay on the board, be it as lone pieces or tied up
in an embrace, stalemate is a moot point. In real games it just
never occurs.
Strategy
My first impression, when confronted with these rules, was that
a game like that would never end, and just muddle on, because
pieces are never removed from play. It was not clear to me how
you could make progress, or even how progress should be defined.
The number of embracing pairs can only increase during the game,
losing the ability to capture, and in particular to embrace the
King. So it seemed to me the game would just peter out before
there was any danger to the Kings. I could not have been more
wrong...
Embracing pairs are actually quite dangerous. Because they act
as 'amplifiers' for the lone pieces. E.g. an embracing Queen on
the target square of a friendly Knight doesn't block a move of
that Knight (as a lone friendly Queen would have done), but
allows the Knight to release that Queen from the embrace, and do
a follow-up Queen move. So it is as if that Knight gets one of
its moves replaced by all the moves of the Queen. So embracing
pairs are far from 'dead wood'. You should be prepaired for the
pieces in there to be released at any time, able to engage in
new embraces.
As there is no limit to the length of release chains, the
releases can also occur indirectly. E.g. an embracing Knight
could be a Knight jump away from an embracing Queen, and when a
lone Rook now releases the Knight, that Knight can release the
Queen. So 'virtual attacks' of a piece tied up in an embrace on
another embracing pair are potential ways to propagate a release
chain to a distant piece, and release that from its embrace. And
the more emracing pairs there are on the board, the more often
pieces in such a pair will happen to have such virtual attacks
on other pairs. If they virtually attack more than one other
pair, a release chain reaching them would branch there, to
continue along two different paths.
As is the nature of branching chain reactions, at some critical
density of embracing pairs the point will be reached where the
average number of virtual attacks per pair will surpass 1. Then
the number of possible chains will 'explode', and it will become
possible to make almost any piece appear from an emracing pair
anywhere, even from a pair it wasn't originally in. To
illustrate this, look at the following simplified example:
[font=courier]8 . . . . . . . .
7 . . . . . . . .
6 . . . . . . . k
5 . . . . . . . .
4 . . . Rp. Rp. .
3 . . . . . . . .
2 . Q . . . . * .
1 . . . . . . . .
a b c d e f g h[/font]
where the Rp indicates a white Rook embracing a black Pawn.
White to move can play (all in one turn) Qxd4, Rxf4, Rxd4, Qxf4,
Rxd4, Rxf4, Qxh6#. Because the embracing Rooks are virtually
attacking each other (i.e. on average 1 virtual attack per pair,
on the edge of criticallity, so you get an infinitely long
chain, but it doesn't branch yet), they can be used as relay
points for other pieces. They can bounce the release
'activation' around and make it return to where it came from,
reactivating the piece that 'lighted the fuse' for another move
in the same turn. Thus allowing it to hop from relay point to
relay point. Each embracing piece virtually attacking a relay
point automatically becomes a relay point itself. E.g. if there
had been an embracing Knight on g2 (virtually attacking Rf4), it
would have been able to act as a relay for the Queen to move to,
say, h1: Qxg2, Nxf4, Rxd4, Rxf4, Nxg2, Qh1! The Queen doesn't
just have her own moves from b2, but can appear from d4, f4 and
g2 as well. It is as if every embracing piece has become a lone
Queen (in addition to g2 being able to come out as a Knight as
well).
Of course embracing pairs can also be moved by the opponent, who
will try to break your most dangerous chains by moving them out
of virtual-attack. But if the density of embracing pairs
increases, it will get progressively more difficult to do that
without creating new virual attacks. In addition, he might not
have the possibility to move them. This in particular happens
when his piece in the embrace is a Pawn, as a Pawn only has a
single move (an embracing piece cannot capture!), which could
easily be blocked. This shows it is particularly favorable to
have your strong pieces embracing opponent Pawns; then you can
rely on them to stay where you want them to act as relays. This
leads to the paradoxical situation that capturing a Queen with a
Pawn is a quite poor move!
As the density of embracing pairs increases during the game, the
attacking power of both players will be more and more amplified.
So that the advantage to have the move becomes larger and
larger. Usually the point where your attacking power gets so
large that the opponent cannot protect his King from embrace in
the next move anymore, is reached long before all pieces are
embracing.
Equipment
HTML http://www.chessvariants.com/membergraphics/MShug-mate/hugs.jpg
Peace Chess can be played with a set of normal Chess pieces, but
it is a bit awkward to cram two such pieces on the same square.
The inventor of Peace Chess (Felix Albers) now sells a very nice
set of Chess pieces especially designed to embrace each other on
a single square. Some of those pieces can be seen in the
photograph above. Looked at from the bottom, such an embracing
pair looks like the Yang-Yin symbol!
#Post#: 357--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: John_Lewis Date: February 2, 2018, 10:15 am
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Just to clarify;
[list type=decimal]
[li]You can't combine your own pieces.[/li]
[li]The combined piece has the powers of both previous
pieces.[/li]
[li]Combining with an already combine piece activates the
previously combined piece of your color and that piece can
move... what is the notation look like for such a move?[/li]
[li]It's possible to mate yourself by combining your King with
an adjacent opposing piece, but does this result in a draw if
you then bounce your own piece into the opposing King?[/li]
[/list]
Thanks, this looks very interesting, particularly the physical
pieces.
#Post#: 359--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: HGMuller Date: February 2, 2018, 10:43 am
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1) Indeed. Moving to a square occupied by a lone piece of your
own, is forbidden (like in orthodox Chess). You can move lone
pieces only to empty squares or squares that contain a (paired
or lone) opponent piece.
2) Yes, in the sense that you never were allowed to move your
opponent's pieces in the first place. So my Rook embracing his
Knight can be moved in my turn like a Rook, but not like a
Knight, as the Knight cannot move in my turn.
3) Well, a simple notation that works in general for variants
where multiple pieces can be moved in one turn would be to just
separate the individual moves by commas. It might be more clear
if a released piece would always be followed by an asterisk as a
disambiguator, like R*xf4.
4) The current rules stipulate that the King can never initiate
an embrace, i.e. instantly loses when he does, without
completing the move for any pieces he released. This makes the
King quite defenseless, however, and unprotected Queen can drive
it to the edge for checkmate. So rule modifications to improve
the King's defense are under study. Allowing the King to embrace
on its own initiative (also after release) is in itself not a
solution, as this would allow the opponent then to 'abduct' the
King by retreating the embracing pair deep into its own camp,
where it would not survive anyway. So it would only work in
combination with a rule that forbids moving a piece that was
embraced by the King. This complicates the rules, however.
#Post#: 379--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: John_Lewis Date: February 3, 2018, 1:50 pm
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1. This makes sense.
2. Oh! I thought you could move the piece as either of the
combined pieces as could your opponent. Is there currently a
rule regarding repetition of combined pieces? A combined
Queen/Rook moving back and forth with checkmate unattainable?
3. Yes, the chained movement is what I was curious about. My
pawn releases my bishop which then releases my rook ... the
notation quickly ends up looking odd if you don't have some way
to show the chaining. Example of chain
notation:c2xb3>Bb3xa2>Ra2xa4
4. So currently the rule could be simply that if the opposing
King is embraces, you immediately win. Wouldn't matter who
initiated it, resolves strange combinations.
#Post#: 381--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: HGMuller Date: February 3, 2018, 3:39 pm
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As to (2), the current rule doesn't forbid undoing the move of
your opponent, if the piece types in the embrace allows that. In
human games this doesn't seem much of a prblem so far, but a
simple demo AI I made for on the website seems to have a
tendency to repeat positions. (Probably also because I did not
put in code to make it recognize that as a draw.) So another
rule change under study is to forbid moving a pair that the
opponent just moved.
#Post#: 393--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: John_Lewis Date: February 4, 2018, 3:49 pm
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There's a little bit of Alice Chess in this (in that you can
both be in the "same square" in Alice Chess) but the joining of
the pieces is quite nice. I like the phrase "embrace" very much
for describing the mechanic. It's like a friendly hug and oh,
let's go move some place you don't want to be for awhile.
It would seem to me that the Knight would increase in value for
such a game because it can "kidnap" an opposing piece and place
it in hard to reach location after leaping... trapping it. Since
an embraced piece can't move into an occupied space, you can
safely embrace the opposing Queen and then move it behind your
own lines where your opponent is stuck and can't move out.
Edge case questions:
A. En Passant, does it still work and if so where does the
embraced piece end up?
B. Embraced pawns reaching the last rank, are they effectively
stuck there or do they promote? Can they promote on the opposing
players turn?
C. Is castling blocked by opposing pieces attacking a square
between the Kind and Rook (embraced or not)?
D. Can an embraced Rook still castle if it has not previously
moved?
E. When you embrace a pawn to an opposing piece, if you later
dislodge it can it choose to either embrace diagonally or move?
I'm assume it can't "move" into a square occupied by an opposing
piece.
#Post#: 394--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: HGMuller Date: February 4, 2018, 4:17 pm
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That is a useful strategic insight, about the Knight. I would
like to build an AI that can play this, in oder to test rule
variations (e.g. how they affect draw rate). But it is very hard
to make an evaluation function; I simply don't know what one
should strive for when embracing the opponent King is not within
the horizon.
As to your questions:
A) The rule book that is delivered with the pieces describes
e.p. capture as moving back the 'captured' Pawn one square to
embrace it, and then move the now released piece from the square
it was. This strikes me as illogical, as there isn't any need to
move the released piece. A more logical way would move back the
entire pair to the square it skipped, and then perform the
capture as normal. It probably wouldn't affect the game much
whether you do one or the other.
B) Pawns reaching last rank promote, even if the opponent
dragged them there. The most practical way to do this in a timed
game is to just press the clock after you dragged the Pawn, so
the opponent can (and must) decide what to replace it with in
its own time, in additio to playing his normal move.
Note that Pawns can also be dragged to first rank. They will
have a double-push from there, which would be subject to e.p.
capture.
C) Indeed, Kings should not travel through squares that are
under real attack (by a lone piece, or through a chain move).
D) It doesn't matter whether the Rook is paired (although it
might not be a good idea to put your King next to a pair).
E) Indeed, only diagonal Pawn moves can embrace (possibly
triggering a release). Moving straight forward is only possible
to empty squares. So an embracing Pawn can very easily be
blocked, and can then neither be released, nor move the entire
pair. It is forbidden to move into an embrace when the released
piece would not have a place to go.
#Post#: 396--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: Greg Strong Date: February 4, 2018, 5:29 pm
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[quote author=John_Lewis link=topic=60.msg393#msg393
date=1517780941]
There's a little bit of Alice Chess in this (in that you can
both be in the "same square" in Alice Chess) but the joining of
the pieces is quite nice.
[/quote]
Actually, that's not quite true. The rules of Alice Chess are
such that the two corresponding squares of a pair can never be
occupied at the same time. (You could, for example, play on a
single board where some pieces sit on top of checkers pieces or
not to designate which "phase" they are in.)
#Post#: 416--------------------------------------------------
Re: Peace Chess (Paco Shako)
By: John_Lewis Date: February 6, 2018, 7:52 pm
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[quote author=Greg Strong link=topic=60.msg396#msg396
date=1517786973]
[quote author=John_Lewis link=topic=60.msg393#msg393
date=1517780941]
There's a little bit of Alice Chess in this (in that you can
both be in the "same square" in Alice Chess) but the joining of
the pieces is quite nice.
[/quote]
Actually, that's not quite true. The rules of Alice Chess are
such that the two corresponding squares of a pair can never be
occupied at the same time. (You could, for example, play on a
single board where some pieces sit on top of checkers pieces or
not to designate which "phase" they are in.)
[/quote]
Interesting, I've played they could occupy the same "space"...
on the other board. This was obviously easier with a computer
taking care of the movement.
We also had variants for White starting on one board and Black
starting on the other board, which I found more fun.
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