I found this on rec.puzzles and thought it might be an idea to cross post it
to rgcm...

"Andrew Bull" wrote in message
...
This puzzle occurred to me the other day, though I doubt it's new; and I'm
not sure if it's trivial, unsolvable or somewhere in between, but here
goes:

Two players alternately place a chess piece (from the standard set of 32)
onto a chess board. The position must always be legal (or able to be made
legal by adding the missing king(s) to (a) suitable square(s)). If at any
point in this process, either king is in checkmate, the first player wins;
otherwise, the second player wins. Given perfect play, who will win?

When this sort of thing is posted I generally don't participate: I just
stand back in awestruck admiration at the way people figure this sort of
stuff out. But I will add my 2c here. I'm not sure I understand the
rationale behind the winner and loser.As stated:
White/Black mates - White wins
Draw - Black wins
As a chess variant wouldn't it make more sense to have:
White mates - White wins
Black mates - Black wins
draw - draw

I hate it when people hijack your thread and start asking questions of their
own but this seems to make more sense. Initially I'd have to say a draw is a
heavy favourite but, hang on a minute, rules are also needed about check: Do
you have to move out of check? Does the mate have to be possible in the
rules of chess ie you can't have a mate simultaneously by, say, six pieces.
What about captures? I think there's mileage in this problem but aisi it
needs restating.

cheers

dd

"DDEckerslyke" wrote in message
...
I found this on rec.puzzles and thought it might be an idea to cross post
it
to rgcm...

"Andrew Bull" wrote in message
...
This puzzle occurred to me the other day, though I doubt it's new; and
I'm
not sure if it's trivial, unsolvable or somewhere in between, but here
goes:

Two players alternately place a chess piece (from the standard set of
32)
onto a chess board. The position must always be legal (or able to be
made
legal by adding the missing king(s) to (a) suitable square(s)). If at
any
point in this process, either king is in checkmate, the first player
wins;
otherwise, the second player wins. Given perfect play, who will win?

When this sort of thing is posted I generally don't participate: I just
stand back in awestruck admiration at the way people figure this sort of
stuff out. But I will add my 2c here. I'm not sure I understand the
rationale behind the winner and loser.As stated:
White/Black mates - White wins
Draw - Black wins
As a chess variant wouldn't it make more sense to have:
White mates - White wins
Black mates - Black wins
draw - draw

I hate it when people hijack your thread and start asking questions of
their
own but this seems to make more sense. Initially I'd have to say a draw is
a
heavy favourite but, hang on a minute, rules are also needed about check:
Do
you have to move out of check? Does the mate have to be possible in the
rules of chess ie you can't have a mate simultaneously by, say, six
pieces.
What about captures? I think there's mileage in this problem but aisi it
needs restating.

Surely the kings would have to be the first two pieces put on the board;
then you could put down your other pieces so as to arrange a checkmate.
Alan

DDEckerslyke wrote:

heavy favourite but, hang on a minute, rules are also needed about check: Do
you have to move out of check?

No. You just put pieces on the board. That also answers your other
questions, I think.

The question of 'legal situation' is a bit of a poser: I think it
would be better to drop it, as you otherwise introduce the problem of
previous and future play -- e.g. in a legal position you can't have two pawns
of the same colour on the same file unless there has been a capture.
But this type of game doesn't have captures... This part is too tricky
for most people -- seems better to allow pieces to be placed anywhere,
even bishops on same colour, and pawns on first and last rank.

--
Anders Thulin ath*algonet.se http://www.algonet.se/~ath

On Mon, 15 Mar 2004 22:21:25 -0000, "DDEckerslyke"
wrote:

I found this on rec.puzzles and thought it might be an idea to cross post it
to rgcm...

"Andrew Bull" wrote in message
...
This puzzle occurred to me the other day, though I doubt it's new; and I'm
not sure if it's trivial, unsolvable or somewhere in between, but here
goes:

Two players alternately place a chess piece (from the standard set of 32)
onto a chess board. The position must always be legal (or able to be made
legal by adding the missing king(s) to (a) suitable square(s)). If at any
point in this process, either king is in checkmate, the first player wins;
otherwise, the second player wins. Given perfect play, who will win?

When this sort of thing is posted I generally don't participate: I just
stand back in awestruck admiration at the way people figure this sort of
stuff out. But I will add my 2c here. I'm not sure I understand the
rationale behind the winner and loser.As stated:
White/Black mates - White wins
Draw - Black wins
As a chess variant wouldn't it make more sense to have:
White mates - White wins
Black mates - Black wins
draw - draw


Reading this reply, I realize how terribly I misread the original
problem when I thought that it worked about the way the replier was
saying it should work.

So, holy cow! Any player can play any piece, Player 1 is just trying
to get *either* king in checkmate... So many tricky issues here...

I suspect that Player 1 sticks the black king against a wall, then
tries to start attacking it, either with a queen in the square right
next to it or... as much as I'd love to say two knights...

Hmm, I guess we're back to that question. If you end up with, say,
two knights attacking the king, will the referee say "That's not a
legal position?" I think to make the puzzle work, the answer has to
be yes.

So, as I work through this, I'm forming the opinion that the second
player will win. The second player will quickly put a checking piece
right next to any king on the board, then ensure that the checking
piece can be captured.

Once the second player has stuck a white queen right next to the black
king, and positioned a black rook right next to the white queen so
that it can capture the white queen, there's no way to add an
additional checking white piece without creating an illegal position.

So, if Player 1's first move is the black king, then Player 2 counters
by putting the white queen right next to it.

If Player 1 doesn't start by putting down a King, then player 2 starts
by putting the white queen or a white rook in the middle of the board,
intending to place the black king next to it on the next turn.

Player 1 might try to counter that by putting the black king against a
wall, but where it is still attacked by that white queen or rook, but
I still say that the answer is:

Player 2 can always win! :-) (Still harder to mate than to avoid a
mate.)

Now, if we're allowing illegal positions, then that's a horse of a
different color. In that case, I say that some king will end up
against a wall, completely surrounded and attacked by 3 or 4 pieces!
--

Wasn't it Dgates who wrote:

So, as I work through this, I'm forming the opinion that the second
player will win. The second player will quickly put a checking piece
right next to any king on the board, then ensure that the checking
piece can be captured.

Once the second player has stuck a white queen right next to the black
king, and positioned a black rook right next to the white queen so
that it can capture the white queen, there's no way to add an
additional checking white piece without creating an illegal position.

So, if Player 1's first move is the black king, then Player 2 counters
by putting the white queen right next to it.

I can't see how the second player gets time to place the black rook next
to the white queen.

I see the game going like this

Me: Black king in a corner
You: White queen right next to it
Me: White rook defends the white queen: checkmate

The position conforms to the requirement of being "legal (or able to be
made legal by adding the missing king(s) to (a) suitable square(s))".

--
Mike Williams
Gentleman of Leisure

On Thu, 18 Mar 2004 18:32:28 +0000, Mike Williams
wrote:

Wasn't it Dgates who wrote:

So, as I work through this, I'm forming the opinion that the second
player will win. The second player will quickly put a checking piece
right next to any king on the board, then ensure that the checking
piece can be captured.

Once the second player has stuck a white queen right next to the black
king, and positioned a black rook right next to the white queen so
that it can capture the white queen, there's no way to add an
additional checking white piece without creating an illegal position.

So, if Player 1's first move is the black king, then Player 2 counters
by putting the white queen right next to it.

I can't see how the second player gets time to place the black rook next
to the white queen.

I see the game going like this

Me: Black king in a corner
You: White queen right next to it
Me: White rook defends the white queen: checkmate

The position conforms to the requirement of being "legal (or able to be
made legal by adding the missing king(s) to (a) suitable square(s))".


Damn, I really need a walkthrough of a sample game from the original
poster.

I suppose the words "If at any point in this process, either king is
in checkmate..." imply that the second player can't add additional
pieces to thwart the checkmate -- in which case, of course player #2
wouldn't put a white queen next to the poor black king.

I'm still willing to go out on a limb and say that the guy trying to
force the mate is going to lose.

In fact, in your example, player #2 just needs to place a white bishop
next to the cornered black king instead of a white queen. There's no
piece that can both defend the bishop and stop the black king from
fleeing.


If this thread continues, maybe I'll try to work out a more exact
strategy, but for now I'll say that player #2 should be looking to
place kings in the center of the board and/or to place a checking
bishop right next to any unchecked kings placed by player #1.

Player #2 wins!
--

Wasn't it Dgates who wrote:
On Thu, 18 Mar 2004 18:32:28 +0000, Mike Williams
wrote:

Wasn't it Dgates who wrote:

So, as I work through this, I'm forming the opinion that the second
player will win. The second player will quickly put a checking piece
right next to any king on the board, then ensure that the checking
piece can be captured.

Once the second player has stuck a white queen right next to the black
king, and positioned a black rook right next to the white queen so
that it can capture the white queen, there's no way to add an
additional checking white piece without creating an illegal position.

So, if Player 1's first move is the black king, then Player 2 counters
by putting the white queen right next to it.

I can't see how the second player gets time to place the black rook next
to the white queen.

I see the game going like this

Me: Black king in a corner
You: White queen right next to it
Me: White rook defends the white queen: checkmate

The position conforms to the requirement of being "legal (or able to be
made legal by adding the missing king(s) to (a) suitable square(s))".


Damn, I really need a walkthrough of a sample game from the original
poster.

I suppose the words "If at any point in this process, either king is
in checkmate..." imply that the second player can't add additional
pieces to thwart the checkmate -- in which case, of course player #2
wouldn't put a white queen next to the poor black king.

I'm still willing to go out on a limb and say that the guy trying to
force the mate is going to lose.

In fact, in your example, player #2 just needs to place a white bishop
next to the cornered black king instead of a white queen. There's no
piece that can both defend the bishop and stop the black king from
fleeing.

Me: Black king in a corner
You: White bishop right next to it, attacking it
Me: White queen at the side of the black king
You: anything you like
Me: White knight defends white queen: checkmate

The king can't flee because the queen attacks the only available space.

The king can't take the bishop because the queen defends it.

The king can't take the queen because the knight defends it.

I suggest that better play might be

p1:1 Black King A8

p2:2 Black Queen B7 (anticipating WQ B8/A7 by player 1,
(and attacking those squares

p1:2 White Bishop C6 (pinning the BQ and thereby allowing
(WQ B8/A7

p2:2 Black Bishop B8 (anticipating WQ A7

p1:3 White Rook A6 (not checkmate because, in normal chess,
(BB - A7 to block it

p2:3 Black ? A7 (forced

p1:4 White Knight B6: checkmate
(BQ can't take WK because of the pin

The checkmate could be prevented by the "?" piece being a second black
bishop, but then there'd be two black bishops on the same colour, and
I'm considering that not to be a legal position.

P1 could also get a checkmate on move 3 by

p1:3 White King A7: checkmate of white by black

Which isn't a legal position in normal chess because the WK must have
been left in check on the previous move. Such a position might be
considered legal in this game. If we consider such positions as illegal,
then we'd really have to do the same for all positions which could not
occur in normal chess, and that's going to be really tough to check when
a large number of pieces have been played. There'd be strange endgames
where the final white pieces can't be played because there are some
doubled black pawns, which can only have become doubled by having taken
a white piece.


If p2 doesn't anticipate WQ B8/A7 then p1 plays that move, then plays to
defend the queen.

However, I think that p2 has an even better play on the first turn

p1:1 Black King A8

p2:1 White Queen D1 (removes the WQ threat by placing it well
(out of the way


--
Mike Williams
Gentleman of Leisure

Mike wrote:
) Me: Black king in a corner
) You: White bishop right next to it, attacking it
) Me: White queen at the side of the black king

That's an illegal position, and it can never be made legal.


SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT

Mike Williams

suggests the attacking strategy:


Me: Black king in a corner
You: White bishop right next to it, attacking it
Me: White queen at the side of the black king
You: anything you like
Me: White knight defends white queen: checkmate

The king can't flee because the queen attacks the only available space.

The king can't take the bishop because the queen defends it.

The king can't take the queen because the knight defends it.

But there's a simple antidote to the mating strategy of putting the
queen next to the cornered king and then defending it: just attack the
queen as soon as it's put down on the board.

For example:

Black puts Black king on a8, White puts White queen on a7
Black puts Black rook on a6.

Now there's no mate threat because of Rxa7.

This sequence also makes me wonder about the definition of "illegal
position". If a legal position is one that can only be reached by some
sequence of legal moves, then in a game starting with the first 3
moves above, White has not only failed to mate Black, he has shot
himself in the foot and will be unable to set up a checkmate for the
remainder of the game.

This is because there is no possible game position in which there is a
queen on a7 attacking a king on a8 and also some _other_ piece
attacking the king. The only situation where you can have two pieces
giving check at the same time is a discovered check, which can't be
done with a queen.

My impression is that this game is very probably an easy draw ---
neither player will be able to force mate if both are paying a
reasonable amount of attention.

Larry T.


I suggest that better play might be

p1:1 Black King A8

p2:2 Black Queen B7 (anticipating WQ B8/A7 by player 1,
(and attacking those squares

p1:2 White Bishop C6 (pinning the BQ and thereby allowing
(WQ B8/A7

p2:2 Black Bishop B8 (anticipating WQ A7

p1:3 White Rook A6 (not checkmate because, in normal chess,
(BB - A7 to block it

p2:3 Black ? A7 (forced

p1:4 White Knight B6: checkmate
(BQ can't take WK because of the pin

The checkmate could be prevented by the "?" piece being a second black
bishop, but then there'd be two black bishops on the same colour, and
I'm considering that not to be a legal position.

P1 could also get a checkmate on move 3 by

p1:3 White King A7: checkmate of white by black

Which isn't a legal position in normal chess because the WK must have
been left in check on the previous move. Such a position might be
considered legal in this game. If we consider such positions as illegal,
then we'd really have to do the same for all positions which could not
occur in normal chess, and that's going to be really tough to check when
a large number of pieces have been played. There'd be strange endgames
where the final white pieces can't be played because there are some
doubled black pawns, which can only have become doubled by having taken
a white piece.


If p2 doesn't anticipate WQ B8/A7 then p1 plays that move, then plays to
defend the queen.

However, I think that p2 has an even better play on the first turn

p1:1 Black King A8

p2:1 White Queen D1 (removes the WQ threat by placing it well
(out of the way

Wasn't it Larry Tapper who wrote:
Mike Williams

suggests the attacking strategy:


Me: Black king in a corner
You: White bishop right next to it, attacking it
Me: White queen at the side of the black king
You: anything you like
Me: White knight defends white queen: checkmate

The king can't flee because the queen attacks the only available space.

The king can't take the bishop because the queen defends it.

The king can't take the queen because the knight defends it.

But there's a simple antidote to the mating strategy of putting the
queen next to the cornered king and then defending it: just attack the
queen as soon as it's put down on the board.

For example:

Black puts Black king on a8, White puts White queen on a7
Black puts Black rook on a6.

Now there's no mate threat because of Rxa7.

Your players seem to be deliberately playing to lose. Player one wins if
he causes a checkmate, but in that example he acted to prevent one.

--
Mike Williams
Gentleman of Leisure