The game is drawn because with the remaining material no sequence of legal moves can lead to a checkmate.

Syzygy tablebases

About

Syzygy tablebases allow perfect play with up to 7 pieces, both with and without the fifty-move drawing rule, i.e., they allow winning all won positions and bringing all drawn positions over the fifty-move line.

The tables provide WDL 50 and DTZ 50 ′′ information. Forcing captures or pawn moves while keeping a win in hand ensures that progress is being made.

DTZ optimal play is not always the shortest way to mate ( DTM ) and can even look unintuitive: For example sometimes pieces can be sacrificed to reset the fifty-move counter as soon as possible. However unlike DTM it achieves the best possible result even with the fifty-move rule.

6-piece tables were released by Ronald de Man in April 2013, including probing code and the generator.

From May to August 2018 Bojun Guo generated 7-piece tables. The 7-piece tablebase contains 423,836,835,667,331 unique legal positions in about 18 Terabytes.

Selected positions