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Aaron
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Joined: July 23rd, 2001, 3:46 pm

Switch the rooks

January 21st, 2006, 1:40 am

In a legal chess game, with both players cooperating, put a white rook on the square originally occupied by a black rook, and a black rook on a square orginally occupied by a white rook, in five moves for each player.There are three different solutions.
 
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needaclue
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Joined: September 22nd, 2005, 8:00 pm

Switch the rooks

January 21st, 2006, 3:31 am

What is the initial condition? Starting from move 0 with all chess pieces laid out? If the board is blank except for the rooks and (say) both kings, this is trivial.
 
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kws
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Switch the rooks

January 21st, 2006, 9:36 am

h4---a5b4---g5h4xg5---g5xb4h1xh7---a8xa2h7xh8---a2xa1
 
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bhutes
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Switch the rooks

January 21st, 2006, 10:33 am

Second solution:h4---a5Rh3---Ra6Ra3---Rh6Rxa5---Rxh4Ra1---Rh8(hope my notation is correct, or atleast understandable --- R=rook)
 
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GM
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Switch the rooks

January 23rd, 2006, 2:44 pm

1. c4 f52. c5 f43. c6 f34. cxb7 fxg25. bxa8(R) gxh1(R)Can do the same with a and h pawns instead of c and f pawns. Does this count as a solution?!
 
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Aaron
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Switch the rooks

January 23rd, 2006, 6:21 pm

kws, one typo:h4---a5b4---g5h4xg5---a5xb4h1xh7---a8xa2h7xh8---a2xa1 bhutes, correct.GM correct.I guess there are more than three solutions. I think of the kws' and bhutes' as one solution, use rook on opposite sides of the board, no pawn promtion; GM's as a second, use rooks on opposite sides of the board with pawn promotion. The third solution, by my count, uses rooks on the same side of the board; that is the white and black rook at the end are both on king side or both on queen side.
Last edited by Aaron on January 22nd, 2006, 11:00 pm, edited 1 time in total.
 
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bhutes
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Switch the rooks

January 25th, 2006, 1:14 pm

h4---g5h4xg5---a5Rxh7---Ra6Rxh8---Rh6AnyMove(non intrusive)---Rh1
 
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Aaron
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Switch the rooks

January 26th, 2006, 5:33 pm

Wow. People keep coming up with more ways. I like this one because it wastes a move, it's the only solution I know that does that.
 
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GM
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Switch the rooks

January 30th, 2006, 2:28 pm

There is another one similar to bhutes' last solution that also uses underpromotion1. h4 a52. h5 g53. hxg6 (en-passent) Ra64. g7 Rh65. gxh8(R) Rxh1
 
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Aaron
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Switch the rooks

January 31st, 2006, 5:29 pm

I love the en passant. Clearly I underestimated the number of ways to accomplish this feat.