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The chess endgame with a king and a pawn versus a king is one of the most important and fundamental endgames, other than the basic checkmates . It is important to master this endgame, since most other endgames have the potential of reducing to this type of endgame via exchanges of pieces. It is important to be able to tell quickly whether a given position is a win or a draw, and to know the technique for playing it. The crux of this endgame is whether or not the pawn can be promoted (or queened), so checkmate can be forced. In the first paragraph of one of his books on endgames, Peter Griffiths emphasized the importance of this endgame: There is simply no substitute to a clear understanding of when and how these positions are won or drawn, not only so that one can play them accurately, but in order to recognize in advance what the correct result should be. If you can do that, you can exchange off quite confidently from a more complex position . In the positions in which the pawn wins, at most nineteen moves are required to promote the pawn (with optimal play) and at most nine more moves to checkmate, assuming that the pawn was promoted to a queen . Except for the section on defending and some actual games, it will be assumed that White has a king and pawn and Black has a lone king. In general, Black should place his king in the path of the pawn to try to prevent its promotion. ==Rule of the square== The first thing to realize is that the pawn may be able to queen unassisted by his king, simply by advancing to the queening square before the opposing king can capture or block the pawn. The ''rule of the square'' is useful in determining whether the pawn can queen unassisted, or whether the king can stop the pawn. In this position, the pawn is on the fifth square from the queening square (counting the queening square itself). A square of five by five squares with the queening square in one corner and the pawn in an adjacent corner can be imagined. (Often, the easiest method of constructing the square is to draw a diagonal mentally from the pawn to the last rank; this is the diagonal of the square). If the black king can move into this square, he can stop the pawn, otherwise the pawn wins the race. In this position, if it is Black's move, he can move to ''b4'' and enter the square, therefore he can stop the pawn. If it is White's move, the pawn advances, the square shrinks to four by four, and the king cannot move into the square, so the pawn queens . See Wikibooks - Chess/The Endgame for further discussion on the rule of the square. Even if the defending king can move inside the square of the pawn, the attacking king may be able to block it, as in the diagram from Fishbein. : 1... Ke4 (moving into the square) : 2. Kb4! Kd5 : 3. Kb5! Kd6 : 4. Kb6! Kd7 : 5. Kb7! Kd6 : 6. a5 Kc5 : 7. a6 Kb5 : 8. a7 and the pawn promotes . Note that in some cases, the king can catch a pawn when he is outside the square by creating threats that must be parried, and gain a tempo. In the Réti endgame study (by Richard Réti, 1921), the white king is outside the square of the black pawn, two tempi short of catching the pawn. However, White can draw by "going after two birds at once". : 1. Kg7! h4 : 2. Kf6! Kb6 If 2...h3 then 3.Ke7 or 3.Ke6 and the pawns promote together. : 3. Ke5! Kxc6 If 3...h3 then 4.Kd6 h2 5.c7, draw. : 4. Kf4, resulting in a draw . 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「king and pawn versus king endgame」の詳細全文を読む スポンサード リンク
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