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A selfmate is a chess problem in which White, moving first, must force Black to deliver checkmate within a specified number of moves against his will. Selfmates were once known as sui-mates. ==Example== The problem shown is a relatively simple example. It is a selfmate in two by Wolfgang Pauly〔(Pauly selfmate )〕〔(W. Pauly )〕 from ''The Theory of Pawn Promotion'', 1912: White moves first, and compels Black to deliver checkmate on or before Black's second move. If White can leave Black with no option but to play Bxg2#, the problem is solved. * White might try moving the bishop, but this is no good, as it will allow Black to play a non-capturing bishop move himself, delaying the mate beyond move two; * moving the knight allows the king to move; * 1.e6 allows 1...exf6 and 2...f5; * 1.f7 or 1.fxe7 allows 1...Kxg7; * 1.g8=Q or 1.g8=R are no good after 1...Bxg2+ 2.Q/Rxg2; * 1.g8=N checkmates Black, which is entirely wrong; * 1.g8=B is also no good, since after 1...exf6 2.exf6 Bxg2+ the bishop can interpose with 3.Bd5. The only move by which White can force Black to deliver checkmate on or before move two is 1.c8=N. There are two variations: * 1...exf6 2.exf6 Bxg2# is quite simple; * 1...e6 leads to the subtler 2.g8=B Bxg2# (this only works because the bishop's path to d5 was blocked when Black played e6). Note that only a promotion to a knight works on move one: any other piece would be able to interpose after 1...Bxg2+. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Selfmate」の詳細全文を読む スポンサード リンク
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