运动中的诗
Poetry in Motion
题目详情
**说明：**对于本月的谜题，请将您的答案提交为 以及你如何得出这个结论的简短解释。谜题是 下面介绍。快乐解决！
有时很难知道您的答案是否正确 尽管完美的游戏玩法将允许礼貌地证明。 当真正证明这是允许的时候，你可能会批评。 但请注意，问题的答案是唯一的。 最快的获胜方式——这就是谜团。 证明它确实获胜需要历史。 因此，请假设当前职位之前的比赛已获得批准。 最后一件事：你最好知道黑色刚刚移动。
Instructions: For this month’s puzzle, please submit your answer as well as a brief explanation of how you arrived at it. The puzzle is presented below. Happy solving!
sometimes it's tough to know you've answered rightly
though perfect game play will permit proof politely.
when really proving it's permissible, you may critique.
However do note the question's answer is unique.
The fastest way to win -- that's the mystery.
Proving that it's really winning demands the history.
So please presume play preceding present position's approved.
Last thing: best you know black just moved.
解析
Original Explanation
The text of the poem in this month’s puzzle suggests that the puzzle has something to do with chess. The first step to solving it is noticing that each of the 8 lines of the poem contains 8 words. The poem itself represents a chessboard, where each word that begins with K, Q, R, B, N, or P represents a king, queen, rook, bishop, knight, or pawn.
Five of the lines are capitalized and three are not; as in FEN notation, the capitalized lines contain white pieces and the un-capitalized lines contain black pieces. The poem asks for the fastest way to win, but notes that the history will be needed to prove that it’s actually the fastest way to win. White could win in 2 moves, but only if black cannot castle. Can we determine from the current state of the board whether black is still able to castle? We will show that black cannot castle by analyzing the chess game itself.
There is no possibility for en passant so we know everything relevant about the board except whether black can castle. We know white’s queen must be a promoted h pawn, since the original queen must have been taken by a knight without moving. Given this, and black’s pawn structure, we know that white must have promoted this pawn on b8, c8, d8, e8, or f8. If white promoted on d8, e8, or f8, then the black kingmust either move or already have moved. If white had promoted on b8, it would have needed to capture all 6 of black’s missing pieces in order to travel that far to the left; however, it cannot possibly have captured black’s bishop in cell c8 which always stays on a different color. If white had promoted on c8, it must have done so from square c7, having captured black’s bishop on square c8 previously via other means. It also must have done so after all of black’s pawn moves, since black’s bishop on f8 has to have come out, and since black’s a pawn must already have promoted. Only a rook could be in square d8 to prevent the black king from having to move after the promotion on c8, but if that were the case, then on the move after the promotion black could only have moved the king or the king’s side rook.
Thus, we can conclude that black has already lost its option to castle, and white can mate in 2 with Rxd7 followed by Qb8#.
Several solvers interpreted the ” — ” in line 5 of the poem to indicate that castling wasn’t available, as a dash in FEN notation will indicate that castling is unavailable. This was unintentional on our part!
Grading this month’s puzzle was a challenge but we generally gave credit to submitters who acknowledged that black could not castle, and found this 2 move checkmate as a result.
Congratulations to everyone who solved this month’s puzzle!