Promotion (chess)

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This article uses algebraic notation to describe chess moves.

Promotion is a chess term describing the transformation of a pawn that reaches its eighth rank into the player's choice of a queen, knight, rook, or bishop of the same color. The new piece replaces the pawn on the same square. Because of promotion, it is possible to have more than one queen or more than two rooks, bishops, or knights. Since the promoted piece starts on the square of the pawn, it is possible to have more than one bishop on the same color of square. Promotion is not limited to pieces that have already been captured.

Promotions to king are allowed in some chess variants, such as suicide chess. As noted below, at one time promotion was not mandatory, and the player could choose to have a pawn reaching the eighth rank remain a pawn. In some fairy chess variants, promotions to pieces of the opposite color are also possible.

Chessboard with extra black and white queen for promotion at 35th Chess Olympiad

Promotion to a queen is often referred to as queening. Since the queen is the most powerful piece, the vast majority of promotions in practical play are to a queen. A promotion to a piece other than the queen is called underpromotion. It occurs more often in chess problems than in practical play. In practical play, underpromotions are rare, but not extraordinarily so (see table below); as the most powerful piece, the queen is usually the most desirable, but promotion to a different piece can be advantageous in certain situtions. A promotion to knight is occasionally useful, particularly if it occurs with check. A promotion to a rook is, on rare occasions, necessary in order to avoid stalemate. Promotion to a bishop almost never occurs in practical play (about one game in 33,000). (See here for examples of underpromotions to rook and bishop made in order to avoid stalemate.)

In the 2006 ChessBase database of 3,200,000 games (many grandmaster- and master-level), about 1.5 percent of the games contain a promotion. In these games (counting games in which multiple promotions by the same player to the same piece occur only once), the fraction of times each piece was promoted to is approximately:

This suggests that about 3 percent of all promotions are underpromotions. The frequency of truly significant underpromotions is, however, less than this. Note that the promotion is not limited to pieces that have been captured. Some chess sets (see Chess piece) come with an extra queen of each color to use for promoted pawns. If no queen is available, an upside-down rook is often used to designate a queen.

[edit] Strategy

The ability to promote is often the critical factor in endgames and thus is an important consideration in opening and middlegame strategy. Almost all promotions occur in the endgame, but promotion in the middlegame does happen.

Promotion occasionally occurs even in the opening, often after one side makes a blunder, as in the Lasker trap, which features an underpromotion to a knight on move seven. Schlechter-Perlis, 1911 could have featured a promotion to queen on move 11: 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.e3 Bf5 5.Qb3 Qb6 6.cxd5 Qxb3 7.axb3 Bxb1? 8.dxc6! Be4?? (Perlis avoided the trap with 8...Nc6!, losing more slowly) 9.Rxa7! Rxa7 10.c7 threatening both 11.cxb8(Q) and 11.c8(Q). The British grandmaster Joe Gallagher pulled off a similar idea a half-move earlier in Terentiev-Gallagher, Liechtenstein Open 1990: 1.d4 Nf6 2.Bg5 Ne4 3.Bf4 c5 4.c3 Qb6 5.Qb3 cxd4 6.Qxb6 axb6 7.Bxb8? dxc3 8.Be5?? Rxa2! and now White could have resigned, since if 9.Rxa2, c2 promotes. Another example occurs after 1.e4 c6 2.d4 d5 3.Nc3 dex4 4.Nxe4 Nf6 5.Ng3 h5 6.Bg5? h4 7.Bxf6?? hxg3 8.Be5 Rxh2! 9.Rxh2 Qa5+! 10.c3 Qxe5+! 11.dxe5 gxh2, with the dual threat of 12...hxg1(Q) and 12...h1(Q).

P. Short-Daly, Irish championship 2006

Position after White's 10th move.

There are also a few opening lines where each side gets a desperado pawn that goes on a capturing spree, resulting in each side queening a pawn in the opening. An example is seen in the position at right, where play continued 10...bxc3 11.exf6 cxb2 12.fxg7 bxa1(Q) 13.gxh8(Q).

Both players promoted by White's seventh move in Casper-Heckert: 1.e4 Nf6 2.Nc3 d5 3.e5 d4 4.exf6 dxc3 5.d4 cxb2 6.fxg7 bxa1(Q) 7.gxh8(Q).^[1]

[edit] History of the rule

The original idea was that a foot soldier that advanced all the way through the enemy lines was promoted to the lowest officer. In medieval ages, the weakest piece was the queen, or farzin, due to its limited move at the time. When the queen acquired its new movement, the game was radically altered. When the fers became the queen, there were objections that a king should not have more than one queen.

At different times, the pawn could only promote to the piece of the file on which it promoted, or on which it started. In Italy in the 18th and early 19th century, the pawn could only be promoted to a piece that had already been captured. This rule was used unevenly, and it was generally abandoned in the early 19th century. Philidor did not like the possibility of having two queens, and in all editions of his book (1749 to 1790) he stated that a promotion could only be to a piece previously captured. This was also the case in a book by Lambe in 1765. Authur Saul published a book in 1814 which gave the unrestricted promotion rule, as did an 1828 book by Jacob Sarratt. By Sarratt's time, the unrestricted promotion was popular, and it was universal by the mid-19th century (Davidson 1981:59-61).

[edit] Old promotion rule

Although the current rules of chess require a pawn that reaches the eighth rank to be promoted to a different piece, that was not always the case. Wilhelm Steinitz, the first World Champion, in his 1889 work The Modern Chess Instructor endorsed the then-existent "Code of Laws of the British Chess Association."^[2] Law XIII thereof provided, "When a pawn has reached the eighth square, the player has the option of selecting a piece, whether such piece has previously been lost or not, whose names and powers it shall then assume, or of deciding that it shall remain a pawn.^[3] Steinitz explained the purpose of this rule by referring to the position diagrammed at left, which he cited from Johann Löwenthal's Book of the London Chess Congress, of 1862:

White to move.

White to play and mate in one.

If White plays 1.bxa8(Q)?? (or any other promotion), Black wins with 1...gxh3, when White cannot stop Black from checkmating him next move with 2...h2#. Instead, White draws by 1.bxa8(P)!!, when 1...gxh3 or 1...Kxh3 stalemates White, and other moves allow 2.Bxg2, with a drawn endgame.^[4] Steinitz wrote, "We approve of the decision of the London Chess Congress, of 1862, although the 'dummy' pawn rule was denounced by some authorities."^[5] The same rule, and the same explanation, are given by George H.D. Gossip in The Chess-Player's Manual.^[6]

[edit] Underpromotion

Promotion to a knight, bishop, or rook is an "underpromotion".

[edit] Promotion to a knight

Promotion to a knight wins

Since the knight moves in a way which the queen cannot, knight underpromotions can be very useful, and are the most common type of underpromotion.

In the top diagram on the right, given by World Champion Emanuel Lasker, White has a huge material disadvantage. Promotion to a queen (by 1.exd8(Q)?) would still leave Black ahead in material. Instead, promotion to a knight with 1.exd8(N)+! wins by virtue of a fork: 1....K any 2.Nxf7 followed by 3.Nxh8 leaves White a piece up with a winning endgame.^[8]

Promotion to a knight draws

Promotion to knight may also be done for defensive reasons; to the right is such a case. Black threatens 1...Rb8 mate. The only move that does not lose for White is 1.e8=N+! The resulting Rook vs. Knight endgame is a theoretical draw.

Zurakhov-Koblentz, Tbilisi 1956

Position after Black's 56th move.

(Position after Black's 78th move)

Tim Krabbé points out that Zurakhov-Koblentz (pictured in the diagrams at left and right) furnishes a very rare example of a game with two "serious" underpromotions to knight. In the position at left, Black threatens 57...Nxg7, and if White avoided this by promoting to queen, rook, or bishop, Black would reach a drawn position with 57...Ne7+! and 58...Nxg8. The only winning move is 57.g8=N! Krabbé notes that this is a rare example of a non-checking knight-promotion.

Twenty-one moves later, the players reached the position at right. Once again, a promotion to anything other than a knight would be a blunder allowing a knight fork, e.g. 79.c8=Q?? Nd6+ and 80...Nxc8, with a drawn ending. White instead played 79.c8=N+! (Here, there are other winning moves, such as 79.Kc5.) Kb8 80.Kb6 and Black resigned, since White cannot be stopped from promoting a third pawn—this time to a queen.

[edit] Promotion to rook or bishop

Because the powers of the rook and the bishop are combined in the queen, there is rarely reason to underpromote to them, but it can occasionally be advantageous, usually to avoid stalemate:

Promotion to a rook wins

P. Short-Daly, Irish championship 2006

Position after White's 70th move.

In the position at left (with White to move), Black threatens to capture White's pawn, and a promotion to queen would be stalemate. Only 1.g8(R)! wins.

At right is a position from a recent game at the Irish championship [1]. Here too, a promotion to queen would allow stalemate: 70...b1(Q)?? 71.Qh3+! Kxh3 stalemate. Instead, the game concluded 70...b1(R)! 0-1

White to play and win.

Herman Mattison
Rigaer Tageblatt, 1914

White to move and draw. Position after fifth move.

In the position at left, promotion to bishop is the only winning move: 1. c8(B)! B\any 2. Nd7 B\any 3. Bb7# 1-0

Less often, underpromotion to bishop or rook may be necessary not to avoid stalemate, but to induce it and thus save a draw in an otherwise hopeless position. To the right is an example from the end of a study by Herman Mattison.

Both king moves lose quickly (they can be met by ...Rgg7, for example), so the pawn must be promoted. 6.b8=Q and 6.b8=R both lose to a capture on c8, and 6.b8=N, while leaving a stalemate after 6...Rgxc8??, loses quickly after 6...Rcxc8. This only leaves 6.b8=B!: since the c7 rook is now pinned, Black must either lose it with a theoretical draw or play 6...Rgxc8 which, with a bishop on b8 rather than a queen or rook, is stalemate.

Underpromotion to knight or rook in practical play is rare, and to bishop is even rarer, but in composed chess problems such as this last example, it occurs more often. Perhaps the most famous example is the Saavedra position. Some cases can be quite spectacular: a study by Jan Rusinek, for example, sees White promoting to knight, bishop and rook in order to induce stalemate. An Allumwandlung is a problem where promotions to all four possible pieces occur. An extreme example is the Babson task, where underpromotions by black are countered by matching underpromotions by white (so if black promotes to a rook, so does white, and so on), white's underpromotions being the only way to mate black in the stipulated number of moves.

[edit] Insignificant underpromotions

Shirov-Kramnik, Amber Blindfold 2005

Position after White's 25th move.

A majority of underpromotions in practical play are, as Tim Krabbé puts it, "silly jokes"—underpromotions made where there is no real need to do so (see External links below). A recent high-level example was the game Shirov-Kramnik, Amber Blindfold, 2005. In the position shown to the left, Black played 25...e1B+. This underpromotion is completely inconsequential as both it and 25...e1Q+ force 26.Qxe1.

[edit] See also

• Lasker Trap - an opening trap that features an underpromotion on the seventh move.
• Chess endgame Endgames usually hinge on promotion
• King and pawn versus king endgame promoting the pawn in a king and pawn versus king ending, if possible.
• Rook and pawn versus rook endgame promoting the pawn in a rook and pawn versus rook ending, if possible.
• Queen versus pawn endgame
• Opposite colored bishops endgame
• Allumwandlung
• Babson task
• Saavedra position
• Rules of chess
• Pawn (chess)
• Chess piece

[edit] Notes

[edit] References

• Davidson, Henry (1981), A Short History of Chess (1949), McKay, ISBN 0-679-14550-8 

• Golombek, Harry (1977), Golombek's Encyclopedia of Chess, Crown Publishing, ISBN 0-517-53146-1 

• Hooper, David & Whyld, Kenneth (1992), The Oxford Companion to Chess (second ed.), Oxford University Press, ISBN 0-19-866164-9 

[edit] External links

• Examples of underpromotion in practical play from Tim Krabbé