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The Lucena Position - Part 2 When the pawn is on the a-file (or h-file) by David Surratt
In Part 1 of our look at
the famous Lucena Position, we reviewed the winning method set out by the
Spaniard so long ago. In this part, we will look at why White cannot
win if the pawn is on the a or h-files (OK, we will even look at the
exception to this exception!). Pawns on the a- or h-files When the pawn is on the a or h-file, the opposing king must
be cut off by more than three files or else the game is drawn. If the
enemy king is four or more files away, then the pawn can win. First,
let's look at the drawn position:
1.Rh1 The rook is heading for b8, in order to take control of the b-file, and hopefully provide some space for the White king to emerge from the corner. 1. ..... Kd7 Black needs to get his king as close as possible to the pawn. 2.Rh8
Kc7
4. ..... Kc8 Black has tos to keep the White king trapped in the corner. If 4...Kc6?? 5.Kb8 and the pawn will queen. 5.Rb1 Rc2
...and the White king remains trapped behind his own pawn, unable to escape. The only way White can win with an a-pawn (or an h-pawn) is when the Black king is cut off by at least four files, as in this position:
[ click here for a javascript board to follow this example on]1.Rh1 As in the prior example, White aims to plant the rook at b8 so that the king can escape from the corner. 1. .....
Ke7
The idea of this move is to deny White the c5 square in some variations. More natural, but losing even faster, is 2...Kd7 3.Rb8 Ra2 4.Kb7 Rb2+ White's next two moves duplicate the winning technique we saw in part one of this article. 5.Ka6 Ra2+ 6.Kb6 Rb2+ 7.Kc5 White will zigzag down the board towards the rook until Black runs out of checks. 3.Rb8
Ra2
Since c5 is out of the question (see note after Black's 2nd move) White makes use of what is available - the c8 square. Black can't plug all of the holes! Note that while White has slowly improved his position, Black can do nothing more than shuffle his pieces. 5. .....
Rc2+ Black ran out of checks but now he threatens checkmate. 7.Rb6+ Kc5
8.Rc6+ A mistake would be 8.Ra6 Rh8+ 9.Kd7 Rh7+ 10.Ke8 ( 10.Ke6?? Rh6+) 10...Rh8+ 11.Kf7 Ra8 and White makes no progress.] 8. ..... Kb5 Of course Black cannot capture the rook, as White then queens with check. Another try is 8...Kd5 9.Ra6 Rh8+ 10.Kc7 Rh7+ 11.Kb6 Rh6+ 12.Kb5 and Black has run out of checks. White wins. 9.Rc8
Rh8+
White wins, as Black must either allow the pawn to queen, or surrender his rook for it. In Part 1 of this article we looked at the basic winning technique in the Lucena Position. In Part 3 we will examine the important question of achieving the Lucena position in the first place.
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