Philidor position

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This article uses algebraic notation to describe chess moves.

Philidor's position usually refers to an important chess endgame which illustrates a drawing technique when the defender has a king and rook versus a king, rook, and pawn. It is also known as the third rank defense, because of the importance of the rook on the third rank cutting off the opposing king. It was analyzed by François-André Danican Philidor in 1777. (Also see rook and pawn versus rook endgame.) Philidor analyzed many positions, some of which have his name associated with them (see the subsequent sections).

Contents 1 Philidor's position, rook and pawn versus rook 2 Queen versus rook 3 Rook and bishop versus rook 4 See also 5 Notes 6 References 7 Further reading 8 External links

[edit] Philidor's position, rook and pawn versus rook

The diagram shows an example of Philidor's position. The important characteristics of the position are (from the point of view of the defender):

• the defending king (White in this diagram) is on the queening square of the pawn (or adjacent to it). The pawn can be on any file.
• the opposing pawn has not yet reached the defender's third rank (its sixth rank).
• the opposing king is beyond the defender's third rank.
• the defender's rook is on the third rank, keeping the opposing king off that rank.

Black would like to get his king to the e3 square and threaten checkmate to force the white king away from the queening square of the pawn, e1. The white rook on the third rank prevents that. If Black checks with the rook from the side, White simply keeps the king in front of the pawn by alternating between squares e1 and e2. If Black offers an exchange of rooks White should take it, since the resulting king and pawn endgame is drawn (see King and pawn versus king endgame).

So Black's only chance of progress is to advance the pawn. The basic idea is for the defender to keep his rook on his third rank until the pawn advances to that rank, then check the opposing king from behind. Here is a possible continuation:

1. ... Rb2

2. Rc3 Ra2

3. Rb3 e3

Black plans to move Kf3, then if he is unopposed, checkmate with the rook or advance the pawn. (A passive defense does not work.)

4. Rb8!

Since now Black's king can not move to e3, it is safe to move the rook away to the far end of the board (the defender's seventh or eighth rank). Note that 4.Rb4+ (??) loses immediately to 4...Kf3 when black will checkmate or force the exchange of rooks followed by Kf2 and promotion of the pawn.

4. ... Kf3

5. Rf8+ Ke4

6. Re8+

The black king can not hide from the checks without giving up the pawn; nor can he approach the rook:

6. ... Kf4

7. Rf8+ Ke5

8. Re8+

The defender's rook must be on his seventh or eighth rank for this defense to work.

To sum up the defense: the defender should keep his king in front of the opposing pawn and keep his rook on the third rank until the pawn advances to that rank, then go to the far end of the board (the seventh or eighth rank) and check the king from behind. If the attacker tries to get his king to his sixth rank by moving his rook to that rank first to block the checks, the defender simply exchanges rooks and has a drawn king and pawn versus king endgame.

Philidor actually studied a position that leads to the type of position above. In this position, if it is Black's turn to move, he moves

1. ... Rb4

and then his rook will reach his third rank, and the position is basically the same as the diagram above, with colors reversed. If White is to move, he wins with accurate play by

1. Ke6 Kf8 (2. Ra8# is threatened, moving the king to the "short side" of the pawn is relatively better than to the other side)

2. Ra8+ Kg7

3. Kd6 Rd4+

4. Ke7 Rb4

5. e6

etc, and wins (Nunn 1999:281-82).

Philidor's defense can also be used if the pawn is less advanced. In that case, the black rook can occupy its fourth rank instead of its third rank and the black king should be on at least its second rank. When the pawn reaches the rank of the black rook, the rook moves to its eighth rank to check the white king from behind (assuming that the opposing rook isn't on that rank) (Howell 1997:42).

[edit] Queen versus rook

Philidor studied many endgame positions. Another one that he studied in 1777 (and is also called Philidor's Position) involves a queen versus a rook (see the diagram).

If Black is to move in this position, he quickly loses his rook by a fork (or gets checkmated). For example,

1. ... Rb1

2. Qd8+ Ka7

3. Qd4+ Ka8

4. Qh8+ Ka7

5. Qh7+

If White is to move in this position, he would like to be in this position except with Black to move. This can be accomplished by triangulation:

1. Qe5+ Ka8

2. Qa1+ Kb8

3. Qa5

and now it is back to the same position but Black has to move (and is in Zugzwang) (Nunn 2002:50-51), (Müller & Pajeken 2008:178). Nunn describes that with the pieces in the center of the board the queen ought to force the rook towards the Philidor position. Nunn describes the various retreat positions for the rook, the "fourth, third, second" rank defenses, then the "Philidor position". The rook can be won in fewer than fifty moves, avoiding the fifty move rule.

[edit] Rook and bishop versus rook

Another famous position studied by and named after Philidor is in the ending of a rook and bishop versus a rook (diagram). White wins because his king has reached the sixth rank and black's king is poorly placed (opposite the white king) (Howell 1997:148-50). If this type of position arises, it is usually because of inferior defense. Nevertheless, it is tricky to win (Nunn 2007:163).

The winning method is as follows:

1. Rf8+! Re8

2. Rf7!

threatening to switch to the other side and checkmate.

2. ... Re2

If 2...Re3 3.Rb7. If now 3...Kc8 4.Ra7 and checkmate on a8, else black loses the rook because the bishop covers b3 (one of the reasons white wants to force the black rook to the third rank). If 3...Rc3 5.Rd7+ and white has achieved the position at move 8 below, only some moves faster. Other second moves for black lose faster : 2...Rh8. 3.Ra7 Rh6+ 4.Be6 with checkmate or loss of rook. 2...Kc8 3.Ra7 Rd8+ 4.Kc6 Kb8 5.Rb7+ Ka8 (5...Kc8 6.Be6+) 6. Rb1 Ka7 (6...Rc8+ 7.Kd7+) 7. Kc7 with checkmate or loss of rook to follow. Correct bishop moves are required for White to win.

3. Rh7 Re1

4. Rb7

The winning line only works if the white rook is on b7 or f7.

4. ...Rc1

Or 4...Kc8 5.Ra7 Rb1 6.Rf7 Kb8 7.Rf8+ Ka7 8.Ra8+. White wins because the chessboard has only eight files.

5. Bb3

This is the key idea. It forces the black rook to the inferior third rank while preventing 5...Rd1+. Black is in zugzwang.

5. ... Rc3

If instead 5...Kc8 then 6.Rb4 Kd8 7.Rf4 Re1 (or 7...Kc8 8.Bd5 Kb8 9.Ra4) 8.Ba4 Kc8 9.Bc6 Rd1+ 10.Bd5 Kb8 11.Ra4. Now White completes the following maneuvers, getting the bishop back to d5 with gain of tempo.

6. Be6 Rd3+

7. Bd5! Rc3

8. Rd7+ Kc8

If 8...Ke8 then 9.Rg7 and checkmate on g8 next move, else loss of rook since the bishop covers f3.

9. Rh7 Kb8

10. Rb7+ Kc8

11. Rb4 Kd8

If 11...Rd3 12.Ra4 and checkmate or loss of rook since the bishop covers b3.

12. Bc4

Stopping the check on d3 and cutting off the rook entirely.

12. ... Kc8

13. Be6+ Kd8

14. Rb8+

and checkmate next move (Howell 1997:148-50), (Nunn 2007:163-64), (Müller & Pajeken 2008:178).

This is an exercise in domination of the king. Interestingly, many of the longest games on record involve this endgame ^[1].

[edit] See also

• Chess endgame
• Rook and pawn versus rook endgame
• Lucena position - a winning position, in contrast to the Philidor position for rook and pawn versus rook
• Cochrane Defense - a drawing position, in contrast to the Philidor position for rook and bishop versus rook
• Computer chess "endgame tablebase" section has queen versus rook played by computer versus human

[edit] Notes

[edit] References

• Howell, James (1997), Essential Chess Endings: The tournament player's guide, Batsford, ISBN 0-7134-8189-7 

• Nunn, John (1999), Secrets of Rook Endings, Gambit Publications, ISBN 1-901983-18-8 

• Nunn, John (2002), Secrets of Pawnless Endings, Gambit Publications, ISBN 1-901983-65-X 

• Nunn, John (2007), Secrets of Practical Chess (second ed.), Gambit Publications, ISBN 978-1-904600-70-1 

[edit] Further reading

• Emms, John (1999), The Survival Guide to Rook Endings, Everyman Chess, ISBN 1-85744-235-0 
• Fine, Reuben & Benko, Pal (1941, 2003), Basic Chess Endings, McKay, ISBN 0-8129-3493-8 
• Korchnoi, Victor (1999, 2002), Practical Rook Endings, Olms, ISBN 3-283-00401-3 
• Minev, Nikolay (2004), A Practical Guide to Rook Endgames, Russell Enerprises, ISBN 1-888690-22-4 
• Müller, Karsten & Lamprecht, Frank (2001), Fundamental Chess Endings, Gambit Publications, ISBN 1-901983-53-6 
• Müller, Karsten & Pajeken, Wolfgang (2008), How to Play Chess Endings, Gambit Publications, ISBN 978-1-904600-86-2 
• Ward, Chris (2004), Starting Out: Rook Endgames, Everyman Chess, ISBN 1-85744-374-8 

[edit] External links

• Interactive Endgame Simulation of the Philidor Position
• Video explaining the Philidor Position