07 September 2006

K+efgh vs. K+fgh

Endgames with four Pawns vs. three Pawns all on the same side occur frequently. Because both players castle Kingside more often than they castle using other possible combinations of castling (both Queenside, on opposite sides, or at least one player doesn't castle), the four vs. three Pawn structure is seen most frequently on the Kingside.

The diagram shows an example where the Pawns have advanced the minimum number of squares. The same structure on the Queenside is just a mirror image.

Most endgame manuals have several examples of this endgame showing various combinations of pieces. For example, 'Rook Endings' by Levenfish and Smyslov has five examples of Rook and Pawn endgames played by world class players. The games have Pawn structures that vary significantly from the diagram, but all have the basic structure with Pawns on the e-, f-, g-, and h-files facing Pawns on the f-, g-, and h-files.

Another excellent book, 'Endgame Preparation' by Jon Speelman, has an entire chapter titled 'One Extra Pawns but Pawns all on One Wing', where the four vs. three structure is seen in several examples from GM level games. Following Speelman's lead, let's look at the win-draw chances with typical material combinations.

  • No other pieces: The King and Pawn endgame is almost always a win for the strong side. Paraphrasing Fine ('Basic Chess Endings' no.69), 'the extra Pawn is used as a decoy to divert the attention of the enemy King', while the White King captures the remaining Pawns.

  • A minor piece on each side: Fine believed that N+4P vs N+3P is a win for White (no.130) and that B+4P vs B+3P with same color Bishops is a draw (no.130, opposite color Bishops is certainly a draw). In the cases of Bishop vs. Knight, the Knight has an advantage over the Bishop (discussion of no.240). That means N+4P vs B+3P is often a win for White, while B+4P vs N+3P is usually a draw; Speelman mentioned that White's winning chances can depend on having an h-Pawn of the right color for the Bishop.

  • A Rook on each side: This is a draw (Fine no.393+), although Capablanca managed to win this endgame twice against strong opponents. Speelman considered that 'it is possible to draw with accurate defense but Black must be very careful.'

  • A Rook and a minor piece on each side: Of the different material combinations, this is the least investigated. The basic endgame manuals don't have the space to examine this in detail. My first impression is that the general rule is the same as 'a minor piece on each side', but this is just an impression. I'll watch out for real examples.

  • A Queen on each side: Speelman wrote, 'The extra Pawn gives some winning chances but I believe that with reasonable defense Black should draw'. He gave no examples, but mentioned that Larsen lost the strong side of this ending against Keres.

Knowing the basic chances to win or draw in these endings helps considerably when deciding how to simplify from more complicated endings.

No comments: