Test your chess: daily chess puzzle # 236

White to play and win

B Rabinowitz v A Schobi 1955

Solution

I struggled with this puzzle, eventually settling on the small retreat 1 Qf4! planning 2 Ng5, hitting h7: and I felt it gave white a strong advantage. Turning on Stockfish it gave the move as its first choice initially, with +1 advantage, hardly startling, before switching to 1 Qd2!, which I will come to below.

There is one, nice, unforced line after 1 Qf4. If 1…Qc7 2 Ng5 f5 then 3 ef!! Qf4 4 Bh7+ Kh8 5 fg mate. In the game, black played 3…e5 and resigned after 4 Bh7+ Kh8 5 fg+ Kg7 6 Be5+.

However, 1…Bd7 is better (after 1 Qf4); 2 Ng5 Bb5 3 Bb5 Qb6 4 c4 and white is better, but it really is a computer position: 4…a6 5 Bd4 Qc7 6 Ba4 Qc4 is unclear to me, with black having three pawns for the piece. Yes, I know that white's activity is good, but to me 'unclear'.

Stockfish prefers 1 Qd2!, and I think the idea is that in the line with Qb6, after white plays c4 the Qd2 defends the Bb2; an impossible detail for me to see in the original position. And if 1…Ng4 then 2 h6 and if 2…g6 3 Qf4 the Ng4 is lost, 3…Ne5 4 Be5; or better 2 Rg1 since 2…Nh6 3 Qh6 because of the pin.

In writing this posting, I also loaded the game into Deep Fritz 13: it initially preferred 1 Qf4; then after a minute switched to 1 O-O, both of which it thinks are +1.5 or so, before after several minutes eventually choosing 1 Qd2, assessing it as winning.

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