The Ulster Masters took place last weekend, in Lisburn C.C.’s new premises, attracting 40 players across two sections. The top section was won by Peter Carroll, for the second year in a row. A full report has been added here.
An unusual ending cropped up in the round two game between David Hill (Strand) and Stephen Scannell (Lisburn). Hill, though heavily outrated, had earlier been three pawns up, but missed several opportunities to close the game out. Finally the game simplified to the diagrammed position. Knight plus two pawns versus knight is normally easily winning. This position is winning, but it turns out to be very tricky indeed, with themes of mutual zugzwang. It’s not easy to understand what’s going on, even with the aid of the Nalimov tablebases; I would find it impossible without them.
54. ?
White now played the natural 54. Kg2?, but it turns out that this should throw away the win. According to the tablebases, 54. Kg1! and 54. Nc5 are the only moves that win.
Scannell erred in turn with 54… Ke5? (only 54… Kf5 and 54… Ng5 draw). After the further 55. Kf2 Ng5 56. Nc5 Kf5 57. Kg2, a mutual zugzwang position was reached.
There followed 57… Kg4 58. e4, again a mutual zugzwang, 58… Nf3, and now White made the final error with 59. Nd7?, letting the win slip: 59. Nd3! is the only move that wins (though this is still far from obvious). Best play then goes 59… Nd2 60. Nf2+! (only move) Kg5 60. Kh2 Nc4 61. Kh3 Ne3 62. Nd3 Kh5 63. Ne5 Kg5 64. Kh2 Kf6 65. Nf3, and White has consolidated.