Bishops of Opposite Colors
The endgame in which both sides posses only pawns and bishops of opposite colors is notorious difficult to win, as the weaker side is likely to create a blockade on the squares controlled by its own bishop. One pawn advantage is usually not enough to force the win. The chances for that exist either when the stronger side has either passed pawns on both wings or connected passed pawns. In the latter case the winning method is to advance pawns in such a manner that they are placed on the squares controlled by enemy bishop, since it makes blockade impossible.
A good idea for the evaluation function is to scale down the material value when the pure bishop of opposite colors ending is encountered. If some more pieces beside the bishops are present on the board, winning the endgame is easier, but requires complex strategy, based rather on zugzwang and attacking possibilities than on simply advancing passed pawns.
- Deep Thought.. What's this rules of Bishops? by Aravind Anumala, rgc, April 11, 1995
- Hossa - Crafty : bishop endgame by Steffen A. Jakob, CCC, October 27, 1999 » Hossa, Crafty
- Opposite Color Bishop Ending by Howard Exner, CCC, November 29, 1999
- Test position (opposite colour bishop)..very hard for chess engines by Masros Tukiran, CCC, September 08, 2005
- Opposite-colored bishops endgame from Wikipedia
- Opposite-colored bishops | Fortress (chess) from Wikipedia
- Bishops of opposite colors, Bishop & Two Connected passed pawns by Jeremy Silman