En passant Chess Puzzles

Background reading

En passant

In chess, describes the capture by a pawn of an enemy pawn on the same rank and an adjacent file that has just made an initial two-square advance. This is a special case in the rules of chess. The capturing pawn moves to the square that the enemy pawn passed over, as if the enemy pawn had advanced only one square. The rule ensures that a pawn cannot use its two-square move to safely skip past an enemy pawn. Capturing en passant is permitted only on the turn immediately after the two-square advance; it cannot be done on a later turn. The capturing move is sometimes notated by appending the abbreviation e.p.

Rules

The conditions for a pawn to capture an enemy pawn en passant are as follows: * the enemy pawn advanced two squares on the previous turn; * the capturing pawn attacks the square that the enemy pawn passed over. If these conditions are met, the capturing pawn can move diagonally forward to the square that the enemy pawn passed, capturing the enemy pawn as if it had moved only one square. If the right to capture en passant is not exercised immediately, it is lost. Making the capture is optional, unless there is no other legal move. Only pawns may capture or be captured en passant. The en passant capture is the only capturing move in chess where the capturing piece moves to a square not occupied by the captured piece. Because many casual players are unfamiliar with or misunderstand the en passant rule, administrators on internet chess sites frequently receive erroneous complaints of bugs, cheating or hacking.

Notation

In algebraic notation, an en passant capture is notated using the capturing pawn's destination square. In both algebraic and descriptive notation, the move may optionally be denoted by appending "e.p." or similar. For example, in algebraic notation, bxa3 or bxa3 e.p. may be used to represent a black pawn on b4 capturing a white pawn on a4 en passant.

Examples

Some chess openings feature the en passant capture. In the following line from Petrov's Defence, White captures the pawn on d5 en passant on move 6: :1. e4 e5 :2. Nf3 Nf6 :3. d4 exd4 :4. e5 Ne4 :5. Qxd4 d5 (see diagram) :6. exd6 e.p. In the diagram, the move 1...g5+ may seem to checkmate White, but it is in fact a blunder: White can (and in fact must) counter this check with the en passant capture 2.fxg6 e.p.#, which cross-checks and checkmates Black. (Black can draw in the diagrammed position by playing 1...Qxf2+.) In a game between Gunnar Gundersen and Albert H. Faul, Black played 12...f7-f5. White could have captured the black f-pawn en passant with his e-pawn, but he instead played: :13. h5+ Kh6 14. Nxe6+ The bishop on c1 effects a discovered check. 14...Kh7 results in 15.Qxg7#. :14... g5 15. hxg6 e.p.# The en passant capture places Black in double check and checkmate (in fact, White's bishop is not necessary for the mate). An en passant capture is the only way a double check can be delivered without one of the checking pieces moving, as in this case. The largest known number of en passant captures in one game is three. This record is shared by three games; in none of them were all three captures by the same player. The earliest known example is a 1980 game between Alexandru Segal and Karl-Heinz Podzielny.

History

In early versions of chess, the pawn could not advance two squares on its first move. The two-square advance was introduced later, between the 13th and 16th centuries, to speed up games. The en passant capture may have been introduced at that time, or it may have come later; references to en passant captures appear in the books by the 16th-century Spanish chess master Ruy López de Segura. The en passant capture was one of the last major additions to European chess.

Draw by repetition and stalemate

In the context of threefold and fivefold repetition, two positions are considered different if the opportunity to perform a given en passant capture exists in one position but not the other. When a player is not in check, and capturing en passant is the only legal move, the player may not claim a draw by stalemate. In his book on chess organization and rules, International Arbiter Kenneth Harkness wrote that people frequently asked if this is the case. Chess players debated this point in the 19th century, with some arguing that the right to capture en passant is a "privilege" that one cannot be compelled to exercise. In his 1860 book Chess Praxis, Howard Staunton wrote that the en passant capture is mandatory in such a position; the rules of chess were amended to make this clear.