
Pauli Chess - weinzierl
https://blog.plover.com/games/double-chess.html
======
mannykannot
"The main idea is: two pieces can be on the same square... Pierre-Françoys
says he wishes that more than two pieces could share a square... The name
“Pauli Chess”, is inspired by the Pauli exclusion principle, which says that
no more than two electrons can occupy the same atomic orbital."

Pierre-Françoys' variant would be Bose chess, I suppose?

~~~
codeflo
Also, shouldn’t true Pauli chess allow an arbitrary number of pieces in the
same square, but no two of the same kind and color?

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smcameron
Back in 1980 or so, my family invented a game that has an interesting
mechanic. Sort of like chess, but also like battleship, with two boards, and
each player can only see his own board. When a player moves, they announce the
piece and which square the piece is departing from, but not which square the
piece is landing on. You track your opponents pieces one move behind.
Collision resolution happens the next time you move the piece, and find out
you did or didn't make it. You're allowed to guess where you're opponent might
be moving and attempt to intercept. There's quite a bit of luck in the game
since you're largely playing blind, but it's the kind of luck that feels more
natural than injecting randomness with dice.

Rules, 3D-printable parts, etc. are here: [http://smcameron.github.io/dueling-
masters-of-space-time/](http://smcameron.github.io/dueling-masters-of-space-
time/)

~~~
downshun
Like Kriegspiel but with half the information and you're in space.
[https://en.m.wikipedia.org/wiki/Kriegspiel_(chess)](https://en.m.wikipedia.org/wiki/Kriegspiel_\(chess\))

An improvement to your pieces design is to copy the idea behind the
internationalized shogi where generals icon is describing its movement
[https://images.app.goo.gl/preLM7N1sb3taqor7](https://images.app.goo.gl/preLM7N1sb3taqor7)
or the duke board game if feeling adventurous

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symplee
Anyone have links to play online?

Some sites I can think of that support other variants:

[https://lichess.org/](https://lichess.org/) (
[https://github.com/ornicar/lila/](https://github.com/ornicar/lila/) )

And some crazier variants:

[https://www.pychess.org/](https://www.pychess.org/) (
[https://github.com/gbtami/pychess-
variants](https://github.com/gbtami/pychess-variants) )

[https://chessvariants.training/](https://chessvariants.training/)

~~~
sova
I bet a superhero from lichess would be happy to bust this out in a weekend

~~~
dmurray
Lichess's policy is generally not to implement tons of variants, even those
that would play nicely with PGN (this wouldn't).

You could definitely hack this together on a fork of lichess, but don't expect
to see it on the main site.

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oh_sigh
Other chess variants beyond the common: 1) friendly fire is on. You can
capture your own pieces if you want.

2) You can move yourself into check, but only if you checkmate your opponent
simultaneously, in which case the game is a tie

~~~
sixstringtheory
One of my favorite variants is suicide chess. The goal is to be the first to
lose all your pieces. All rules are the same with one addition: if you can
take a piece, you must.

~~~
kick
It's really fun! You can play it on Lichess under "Antichess."

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karmakaze
> 5\. Pieces of opposite colors sharing a square do not threaten one another.

This is going to be strange with kings. You could capture a piece in a square
with a king and the king would require two moves to capture it, and if it was
a queen the king couldn't move. Then just have to check the square for mate.

~~~
jackhalford
I don't think that could happen, if an opposing king shares a square with
another piece, you would choose to take the king to win the game.

~~~
codeflo
You don’t capture kings in chess, and I don’t think that changes in this
variant (at least the article doesn’t suggest that). If you attack the square
with the king on it, the king is in check. If there’s no legal move that puts
the king out of check, that’s checkmate.

Perhaps interestingly, you can create a discovered check with two pieces on
the same square, say two rooks. Like a double check in regular chess, you
can’t remove the check by capturing, because you would only capture one of the
rooks.

~~~
irishsultan
> Perhaps interestingly, you can create a discovered check with two pieces on
> the same square, say two rooks. Like a double check in regular chess, you
> can’t remove the check by capturing, because you would only capture one of
> the rooks.

That wouldn't work. The king would have been in check because of the first
rook already, so either the king had to move away, the first rook would have
been captured on the previous move, something would have been placed between
the king and the rook, or it would have been checkmate.

Unless of course the two rooks would have been in place but you create the
check by removing an obstacle, that would work.

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downshun
Alphazero mastered chess by already-implemented self-play.

A slight change in the game rules can have a significant effect on the game
and strategy, as anyone that delves into chess variants knows. Is the same
true for their implementations?

What is the limitation for state of the art AI in adapting in such a way to
rule changes?

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shmageggy
Turns out DeepMind has already been working on exploring variants with
Vladimir Kramnik!

[https://www.chess.com/article/view/no-castling-chess-
kramnik...](https://www.chess.com/article/view/no-castling-chess-kramnik-
alphazero)

Currently they have to train from scratch, but adapting to new tasks is an
active area of research for RL broadly.

~~~
dmurray
No-castling chess didn't need to be trained from scratch. Starting with a
trained or partly-trained AlphaZero would certainly have worked, since no-
castling chess is a strict subset of chess. The only reason not to is if you
are DeepMind and training resources are really cheap.

For more esoteric variants like this, it makes sense to start from scratch,
though eventually you could imagine an AI that is good at adapting to all
perfect-information two-player games, or even others.

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aj7
Just switch the knights with the bishops, and you're in a different universe.

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pontifier
I dreamt about playing chess last night because of this... very very strange.

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lihaciudaniel
Either two pieces can be on same square this would definitely mess with
tactics. But strategically speaking is just like normal chess but with more
squares

~~~
crystaln
Not at all. As the page says, you can’t block pawns, which entirely changes
the game. You also don’t need to move pawns to develop pieces.

~~~
sova
Super leaky chess? Looking forward to an implementation so I can try and wrap
my mind around how it works. What's to prevent both players from pushing all
pawns through the leaky sieve and promoting everything to Queens right off?

~~~
downshun
Captures

