SML Chess Academy
Extended square, Karstedt manoeuver n Frontal attack
There are some concepts in Rook endings where it can be decided if it can control the opponent from Pawn promotion. There are three different concepts that clearly indicates how the position can be evaluated to see if that result in a win for the player having the Rook or it is going to end in draw. Those three concepts are the Extended square, the Karstedt manoeuver and the Frontal attack. Each of them are detailed below.​
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Extended square
The Rook controlling the Pawn's Queening square and if the King can go to control that Queening's square UNINTERRUPTED in the shortest route, then it is possible to stop the Pawn from Queening which can be determined by the Extended square.
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In the diagram shown, the Black King needs '1' move and the Pawn needs '3' squares to get promoted that makes a total of '4' moves. The yellow shade of a 4 x 4 square from the Pawn's Queening square. The Extended square (shaded green - left and top of the yellow squares) is just one square extended diagonally to have one extra File and Rank towards the White's King. If the White's King can enter into the square and can also reach the Pawn's Queening square 'uninterrupted' then the White will be able to control the game and win, else it results in a draw.
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Note that the UNINTERRUPED reachability to the Queening square by the White's King is important and also it has to be the shortest route and a longer route won't serve the purpose.
Karstedt manoeuver
The position on the diagram is a Lucena position with the Black's Pawn on 7th Rank getting ready to get promoted but the promotion square being occupied by its own King. The result is decided here based on who has to make the move.
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Should that be the Black's move, it can use the bridge manoeuver and is a win and the question is if it is White's move what would be the result? It would be draw. How ??
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The rule says that if there is at least a '3' File distance between the Black King and the defender's (White) Rook with the defender's (White) King on reaching the shorter side of the board with respect to the Black's Pawn. The manoeuver is called as the Karstedt and can be used to draw the game with the above rule in place. The Black King can be continuously checked by the White Rook and it can't attack the Rook thus resulting in a draw.
Frontal attack
In the diagram shown, like the Karsdedt manoeuver rule, there is a distance between the Black's Rook and White's Pawn, but it is along the Rank (a '3' Rank distance) and it can be helpful in drawing the game irrespective of who moves first.
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The defender (Black) can actually draw when the opponent's (White) Pawn hasn't crossed the 4th Rank. Of course, a careful play by Black can save the game even if it is White's move.
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Note:
The Rook's Pawn might not hold true with any of the rules mentioned above as they are special cases always. For instance, a bridge manoeuver in a Lucena position is not possible with a Rook's Pawn.
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A Rook is always better behind its Passed Pawn - to secure a win or at least a draw.