The Lucena position is one of the most famous and important positions in chess endgame theory.
It is named after the Spaniard Luis Ramirez Lucena, although is something of a misnomer, because the position does not in fact appear in his book on chess, Repetición de Amores e Arte de Axedrez (1497). It does appear, however, in Alessandro Salvio's Il Puttino (1634), a romance on the career of the chess player Leonard da Cutri, and it is in that form that it is given here.
The position is shown to the right (it should be noted that the position can be moved as a whole so that the pawn is on any of the files b-g). White's aim is to either promote his pawn or else compel Black to give up his rook for it. Either result will leave White with an overwhelming material advantage and a straightforward win. White has managed to advance his pawn to the seventh rank, but it prevented from queening because his own king is in the way. White would like to move his king and then promote his pawn, but is prevented from moving to the a-file by the black rook, and prevented from moving to the c-file by the black king.
An obvious approach by White such as 1.Rd1+ Ke7 2.Kc7 gets nowhere (these moves are given in algebraic notation). Black can simply harass the white king with checks, and white makes no progress: 2...Rc2+ 3.Kb6 Rb2+ 4.Ka7 Ra2+ 5.Kb8 brings White back where he started.
White can win, however, with 1.Rd1+ Ke7 2.Rd4. Now, if black plays a "nothing" move, like 2...Ra1, hoping to harass the White king with checks again as in the above variation, white continues 3.Kc7 Rc2+ 4.Kb6 Rb2+ 5.Kc6 (or Ka6) Rc2+ 6.Kb5 Rb2+ 7.Rb4. Black cannot prevent the pawn from queening. White shielding his king and pawn with the rook in this way is known as "building a bridge".
Alternative approaches are no better for Black. 2...Rb2, for example, stopping White from carrying out his plan, fails to 3.Ra4 followed by 4.Ka8 or 4.Ka7 and queening the pawn. For example, 1.Rd1+ Ke7 2.Rd4 Rb2 3.Ra4 Kd7 4.Ka7 Kc7 5.Rc4+ chases the black king away and allows the pawn to promote.
Because the endgame rook and pawn versus rook occurs quite often in chess, this position is very important. As it is a known win, endgames sometimes revolve around one player trying to reach the Lucena position and the other trying to prevent it.
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