Endgame (chess)

The endgame in chess (or end game or ending) is the part of the game when there are few pieces left on the board. Alternatively, endgames begin when the middlegame is over, and kings are relatively safe.

Features of endgame play

There are three main strategic differences between earlier parts of the game and endgame: the

• Pawns: during the endgame, pawns become more special. In the endgame, one thing players try to do is to promote a pawn by advancing it to the eighth rank.
• Kings: may become strong pieces in the endgame. The king may be brought towards the center of the board. There it can support its own pawns, attack the opponent's pawns, and oppose the opponent's king.
• Draws: in the endgame, a game may be drawn because there are too few pieces on the board to allow a player to win. This is one of the main reasons for games to be drawn.

All endgame positions can be put into two camps. On the one hand are positions which may be won by force. On the other hand are positions which are drawn, or which should be drawn. The ones that are drawn for certain may be legally drawn (mate could not happen) or drawn by chess experience (no sane defence could lose). All endgames in master chess revolve around the borderline between winning and drawing. Generally, once a 'textbook' drawn position is reached the players will agree a draw; otherwise they play on.

Endgames can be studied according to the type of pieces that remain on board. For example, king and pawn endgames have only kings and pawns on one or both sides and the task of the stronger side is to promote one of the pawns. Other endings are studied according to the pieces on board other than kings, e.g. rook and pawn versus rook endgame.

Basic checkmates

Basic checkmates are positions in which one side has only a king and the other side has one or two pieces, enough to checkmate the opponent's king. They are usually learned at the beginner stage. Examples are mate with K+Q v K; K+R v K; K+2B v K; K+B&N v K (this one is quite difficult).

Technical endgames

R,K,P vs R&K

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

This is a certain win for White with best play

Positions for which the result is certain, given best play, are technical positions. The best example is the analysis by computer chess engine of all possible positions with six pieces or fewer. This is called proof by exhaustion or exhaustive proof. It is logically the same as proving a mathematical theorem by proving the complete set of individual cases covered by the theorem.

Endgame tablebases

After the chess engine has analysed the positions, the results are put into an endgame tablebase for easy retrieval by users. Working with a database to discover previously unknown facts is called 'data mining'.

A number of interesting and surprising facts have indeed emerged. For example, For all three- to five-piece endgames and pawnless six-piece endgames, a complete list of mutual zugzwangs has been tabulated and published.

Another case is the longest sequence of moves to reach a definite result, called 'Depth to conversion'. In May 2006, Bourzutschky and Konoval discovered a KQN vs KRBN position with an astonishing DTC of 517 moves.