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Benutzer:Der-Wir-Ing/Rook and pawn versus rook endgame 1

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The chess endgame of a rook and pawn versus rook is of fundamental importance, and has been widely studied. Endings with rooks and pawns are the most common type to occur in games, occurring in about 10% of all games Vorlage:Ref harvard. Rook and pawn endings with more pawns have the potential of being reduced to this type of endgame. Indeed, an entire 352-page book has been written about this ending: Secrets of Rook Endings by John Nunn. Some complicated wins require more than sixty moves, so the fifty move rule may come into play in competition. The play revolves around whether or not the pawn can be promoted. If the pawn queens, that side will have an overwhelming material advantage. If the pawn is about to promote, the defending side may give up his rook for the pawn, resulting in an easily-won endgame for the superior side. In a few cases, the superior side gives up his rook in order to promote the pawn, resulting in a won queen versus rook position. Precise play is usually required in these positions.

A general rule of thumb (with exceptions) is: if the king on the side without the pawn can reach the queening square of the pawn, the game is a draw; otherwise it is a win for the opponent (except with a rook pawn, i.e. a- or h-file) Vorlage:Ref harvard. The side with the pawn can strive for the Lucena position, which is a win. The other can aim for the Philidor position, which is a draw. There are other types of positions to consider too.

Terminology

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In the following discussion and positions, assume that the side with the pawn is white. Algebraic chess notation will be used.

Ranks are considered to be counted from that player's side of the board. Thus, "the rook's third rank" would be the third rank counting from that player's side of the board. The ranks for the white pieces correspond to the rank in algebraic notation whereas the ranks for the black pieces is reversed.

In these positions with one pawn, the pawn's file divides the board into a "short side" and a "long side", in which the long side consists of more files than the short side.

Pawns are referred to by the file on which they reside: a rook pawn is on the a- or h-file, a knight pawn is on the b- or g-file, a bishop pawn is on the c- or f-file. A central pawn is a queen pawn or a king pawn, on the d- or e-file.

Winning methods

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In order to force a win with the extra pawn, normally the black king must be cut off from the pawn by the white rook along a rank or file, and that isn't always sufficient.

The black king is cut off along a rank

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Vorlage:Chess diagram If the black king is cut off from the pawn along a rank (as in the diagram), White wins easily Vorlage:Ref harvard.

1. Kd6 Rd8+
2. Ke6 Re8+
3. Kd7 Rg8

Checks from the front or side don't help Black.

4. d6 Rg7+
5. Kc8 Rg8+
6. Kc7 Rg7+
7. d7

and the pawn will soon queen.

The black king is cut off from the pawn's file

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When the black king is cut off from the pawn's file the outcome depends on where the black king is in relation to the pawn. Black's king is often cut off from the pawn along a file. some general rules (with exceptions) are:

  • If the pawn is a rook pawn, the position is usually a draw.
  • If the pawn is on the fifth rank (or sixth or seventh rank) with its king near, and the black king is cut off from the pawn's file, White wins.
  • If the pawn is on the third or fourth rank with its king near, White wins only if the black king is cut off three files from the pawns file in the case of a knight's pawn, or two files for a bishop or center pawn.
  • If the pawn is on the second rank and the black king is on the fourth or fifth rank, White wins only if the opposing king is cut off five files from the pawn Vorlage:Ref harvard.

The rule of five

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Vorlage:Chess diagram

Soltis states the rule of five for positions in which the pawn is protected and the opposing king is cut off by files: Add the number of rank of the pawn to the number of files the defender's king is cut off. If the sum is more than five, it is a win. Vorlage:Ref harvard. For example, in the diagram, white wins by:

1. Kc4 Rc8+
2. Kb5 Rd8
3. Kc5 Rc8+
4. Kb6 Rd8
5. Rd1! Kf6
6. Kc7 Ra8
7. d5

and White will win.

The Lucena position

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Vorlage:Chess diagram

Main article: Lucena position

The Lucena position is one of the most famous and important positions in chess endgame theory. It is a win for the side with the pawn. The essential characteristics are that White's king is on the queening square in front of his pawn, the pawn is on the b through g files, and the black king is cut off on a file.

White wins in the position in the diagram by 1. Rd1+ (see algebraic chess notation), forcing the black king one file farther away, then bringing rook to the fourth rank, then bringing out the king, which will be checked by black's rook. White maneuvers his king to the fifth rank (without giving up the pawn) and then when the black rook checks, White interposes his rook and has a winning position. See Lucena position for more details Vorlage:Ref harvard.

Alternate method for bishop pawns and central pawns

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Vorlage:Chess diagram

The Lucena position is a win for White if the pawn is not a rook pawn. There is another way of winning if the pawn if a bishop pawn or central pawn.

In the diagram, 1. Rc2+ would start the process of winning with the process above. However, White also wins by

1. Rh2 Rf3
2. Rh8 Rf1
3. Rf8 Re1
4. Kf7

Vorlage:Ref harvard. Now either

4. ... Kd7
5. e8=Q+ wins, or the white king can approach the black rook on the two files next to the pawn's file until it can no longer check:
4. ... Rf1+
5. Kg6 Rg1+
6. Kf5 Rf1+
7. Kg4 Rg1+
8. Kf3 Rf1+
9. Ke2

and the black rook can no longer attack and the pawn queens (promotes).

Defensive methods

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Often White will not be able to utilize one of the winning methods. Black has several defensive methods available, depending mainly on the position of the pawn and his king.

The frontal defense

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Vorlage:Chess diagram

The Frontal Defense is one of the main ways that Black can keep white from getting to the Lucena positon. Black's rook is well-placed on its first rank and can check the white king or offer itself for exchange when the resulting king and pawn versus king endgame is a draw. The father back the pawn is, the more likely the defense is to be successful. The file of the pawn matters too. Black draws in the diagram:

  1. Kh4 Rh8+!
  2. Kg5 Rg8+
  3. Kh5 Rh8+
  4. Kg6 Rg8+
  5. Kh5 Rh8+

and White can not make any progress Vorlage:Ref harvard.

Note: Black to move has an alternative drawing method that requires knowledge of king and pawn versus king:

  1. ...Rf8 to bring the king over to the pawn. If
  2. Rxf8 Kxf8
  3. Kf4 Kg8! (avoids losing the opposition. Kh4 is met the same way)
  4. Kf5 Kf7 or Kg5 Kg7

The back-rank defense

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Vorlage:Chess diagram

The back-rank defense works if the pawn is a rook pawn or knight pawn. In the diagram, Black draws. If 1. g7 then 1... Rb6+ draws and if 1. Rg7+ then 1... Kh8 draws. White's best attempt is:

1. Kg5 Rc8 (waiting passively, also known as the passive defense)
2. Kh6 Rb8
3. Rg7+ (the only trick for White)
3. ... Kh8!

If 3... Kf8? then 4. Kh7 Rb1 5. Rf7+ Ke8 6. Rf4 and White gets to the Lucena position.

4. Rh7+ Kg8
5. Ra7 Rc8

and White makes no progress. The defense fails for other pawns because White has another file available to go around the pawn Vorlage:Ref harvard.

The black king is on the queening square, the Philidor position

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Main article: Philidor position

Vorlage:Chess diagram

Philidor's position (see the diagram) illustrates an important drawing technique in this endgame. Black keeps his rook on his third rank to keep the white king from reaching that rank. If White advances the pawn to its sixth rank (Black's third rank), then the king is deprived of shelter, so Black moves his rook to the eight (or seventh) rank, and keeps checking the white king from behind. It is very important that the defender keep his rook on his third rank, and move to the far side of the board only after the attacking pawn has moved to its sixth rank. (An exchange of rooks will result in a drawn position, see king and pawn versus king.) See Philidor position for more details Vorlage:Ref harvard.

There are three errors that Black must avoid:

  1. Immobilizing the rook
  2. Allowing the king to be driven away from the queening square
  3. Playing the king to the wrong side

Philidor's defense can also be used with the black rook on the fourth rank, if White's king and pawn have not reached that rank. If this defense is used, the black king should be on the second rank. The principle is the same: Black keeps his rook on the fourth rank, keeping the white king from advancing to that rank. If the pawn advances to that rank, Black moves the rook to the eighth rank and checks the king from behind.

The black king is in front of pawn, but can't reach the Philidor position

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Vorlage:Chess diagram

Vorlage:Chess diagram

Sometimes the defender's king is in front of the pawn, but the rook can't get to its third rank to reach the Philidor position. Thus he has two choices: try to attack from behind, or retreat the the back rank with his rook to guard the mating threats. The diagrams show such back-rank positions.

For a bishop pawn (see the diagram) or central pawn, if the defending rook is tied down to the back rank, he loses:

  • 1 ...Rg2+
  • 2 Kf1 (or Kh1) Rh2!
  • 3 Kg1 f2+
  • 4 Kf1 Rh1+ winning the rook

But the defender can hold the draw with an accurately-conducted "active defense" from behind the pawn while it is still on the fifth rank, with the king moving to the short side (see next section).

But with a knight's pawn (see the diagram), the attacker has no file equivalent to 2... Rh2, so he can't make progress. Here, the defender should avoid the active defense (attacking the pawn from behind while it is on the fifth with the rook) fails, because his king will be forced to the long side (stepping the other way would lose immediately because of the corner, allowing immediate mate).

The defender can draw against the rook pawn either way, because most king and pawn versus king positions are drawn with the rook's pawn (see King and pawn versus king#Rook pawn), Vorlage:Ref harvard, Vorlage:Ref harvard, Vorlage:Ref harvard.

The "short side" defense

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Not all positions similar to the Lucena position above are wins for the superior side — it depends on the position of Black's rook and king (relative to White's pawn), and which side is to move. In positions such as the position in this diagram, the defending rook must be at least four files away from the pawn on the "long side" for the defense to work (the "checking distance"); otherwise the white king can support its pawn and approach the black rook to drive it away. The black king needs to be on the "short side" so it will not block checks by its own rook. Vorlage:Chess diagram As an example, Black to move draws in this diagram. The reason is that Black can check the white king from the side with his rook, and the rook is just far enough away from the white king that if it tries to approach the rook to stop the checks, the rook can get behind the pawn and win it, resulting in a drawn position. For example:

1. ... Ra8+
2. Kd7 Ra7+
3. Kd6 Ra6+
4. Kd5 Ra5+
5. Kc6 Ra6+ (if 5 ... Ra8 6. Ra1! (either black takes the rook and the white pawn queens, or it forces the enemy rook off the vital a-file that has "checking distance", the rook moves on the back rank, followed by 7. Kd7, and the pawn promotes)
6. Kb7 Re6

with a draw after winning the pawn, which can no longer be defended by its king. Note that if White's king and pawn are moved to the left, White wins as in the Lucena position above. The defending rook must be at least four files over from the pawn for this defense to work (which is why the defending king should go to the short side, to not block checks by his rook).

For example, with the black rook on the b-file,

1. ... Rb8+
2. Kd7 Rb7+
3. Kd8 Rb8+
4. Kc7 Re8
5. Kd7

wins. The rook was too close to the pawn, so White's king could both approach the rook to prevent checks and return to protect the pawn.

The position of the black king is important too. If Black's king is on g8 instead of g7 in this diagram, White has the move Rf8+ available, which will enable him to win: after

6. ... Re6

as above,

7. Rf8+

followed by

8. e8=Q

with a winning position.

The short side defense, less advanced pawn

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Vorlage:Chess diagram

1. Kg6 (threatens 2. Ra8+ Ke7 3. f6+ driving the black king far from the pawn (see Lucena Position next section for White's winning method)). 1... Rb6+ is too late because of 2. f6, forcing Black to retreat to the back rank, which is a loss as shown in the previous section. The point of Philidor's third rank defence is to prevent White from moving the king to the sixth rank before the pawn.

Vorlage:Chess diagram

Black's defence is:

1... Rf1 (Tarrasch rule, rook behind pawn)
2. Kf6 (second diagram) (2. Rf8+ Ke7 and now the black rook stops 3. f6+) Kg8! (going to the short side is vital, as will become clear)
3. Ra8+ Kh7
4. Rf8

Other moves make no progress because of black's obeying the Tarrasch rule. E.g. 4. Ke6 Kg7 and 5. f6+ is impossible. The main move protects the pawn and threatens 5. Ke7 followed by f6) Ra1! (now Black threatens to check from the side to keep White from making any progress. He needs space to do this, which is why the king must move out of the way to the short side. Black's rook must be at least three files away from the pawn, otherwise White's king can protect his pawn while attacking Black's rook and gain time necessary to advance the pawn.

5. Re8 (one try, to use the rook to block the checks from the side)
5... Rf1!

Black moves behind the pawn again, so 6. Ke6 is answered by 6... Kg7, as per note to move 4.

The long side blunder

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If the black king went to the long side, Black would not have the resource of checking from the side. For example, from the second diagram above, where '2... Kg8! draws as shown above:

2... Ke8?
3. Ra8+ Kd7
4. Rf8! Rh1
5. Kg7 Ke7 (there is no room to check on the side. If 5...Rg1+ then 6.Kf7 followed by f6.
6. f6+ (the point of 4. Rf8) Kd7 (6...Ke6 7. Re8+ Kd7 8. Re2 and converts to Lucena position, next section)
7. Kf7 followed by Ra8 then Ra2-d2+ (or any other safe check on the d-file).

After this, and the same if Black prevents the check by placing his own rook on the d-file, White plays Kg7 Rg(any)+; Kf8 then f7, reaching the Lucena position.

If the pawn is a central pawn, going to the long side with the defending king will give the rook just enough checking distance if it is on the rook file on the opposite side of the pawn Vorlage:Ref harvard. Defending this way is a far more arduous task, so moving the defending king to the short side is always recomended Vorlage:Ref harvard. With the defending rook three files over from the pawn, the attacker usually wins, but there are exceptions, depending on the location of the attacking rook Vorlage:Ref harvard.

The last-rank defense

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Vorlage:Chess diagram

In the diagram, Black draws:

1... Re8!
2. Kd6 Rb8!

if 2... Rg8 then 3. Ra1!. If 2... Kf6 then 3. Ra1! Rb8 4. Rf1+ Kg7 5. Kc6 Ra8 6. Ra1, a winning position

3. Kd7 Re8

and White can not make any progress Vorlage:Ref harvard.

Rook pawn

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Vorlage:Chess diagram If the pawn is a rook pawn, the chances of a draw are much greater. Even the equivalent of the Lucena position is no guarantee of success (it depends on the location of the white rook and who is to move).

In this diagram, the only way for White to make progress is to get his rook to b8, but this allows the black king to get to the c-file and draw.

1. Rh2 Kd7
2. Rh8 Kc7!
3. Rb8 Rc1
4. Rb2 Rc3!

This is the simplest way for Black. Now there is no way to force the black king away from the c-file.

5. Rb7+ Kc8
6. Rg7 Rc1

and Black draws.

Vorlage:Chess diagram If the black king is cut off by one more file, White wins, as in this diagram:

1. Rc3! Ke7
2. Rc8 Kd6
3. Rb8 Ra1
4. Kb7 Rb1+
5. Kc8 Rc1+
6. Kd8 Rh1
7. Rb6+ Kc5
8. Rc6+! Kd5
9. Ra6

and White wins Vorlage:Ref harvard.

The Vancura position

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Vorlage:Chess diagram The Vancura Position (see diagram) is a drawing position with a rook and rook's pawn versus a rook, when the pawn is not beyond its sixth rank, and the stronger side's rook is in front of the pawn Vorlage:Ref harvard. Black's rook attacks the pawn from the side from some distance away, while keeping the white king from finding cover from checks. Black keeps attacking the pawn Vorlage:Ref harvard. Black's king must be on the opposite side of his rook as the pawn to not block the attacks. Also, Black's king must be nearby the opposing corner if the pawn advances to its seventh rank so the white rook can't check the black king and then support the advance of the pawn, or sacrifice its pawn to skewer Black's king and rook on the seventh rank.

1. Kb5 (Protecting the pawn in order to free the rook to move. If 1. a7 Ra6! 2. Kb5 Ra1 3. Kb6 Rb1+ 4. Kc7 Rc1+ 5. Kd7 Ra1, and White can't win. Note that if Black's king was on g6 there would follow 2.Rg8+ with 3.a8=Q, and if it was on f7 White wins with 3.Rh8! Rxa7 4.Rh7+.)
1. ... Rf5+!
2. Kc6 Rf6+ (an important square for the rook)
3. Kd5 Rb6 (Keeping the attack on the pawn.)
4. Ke5 (If 4. a7 then 4. ...Ra6 draws.)
4. ... Rc6
5. Ra7+ Kg6
6. Kd5 Rf6
7. Kc5 Kh6
8. Kb5 Rf5+
9. Kb6 Rf6+
10. Kb7 Rf7+
11. Kb8 Rf6, etc.

or

3. ... Rf5+
4. Ke6 Rf6+ (an important square for the rook)
5. Ke5 Rb6
6. Kd5 Rf6
7. Ra7+ Kg6
8. Ra8 Kg7 and White can't win. The white king can't advance because of the checks and the pawn can't advance because the black rook gets behind the pawn Vorlage:Ref harvard.

References

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See also

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Category:Chess endgames

uk:Тура та пішак проти тури

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