Cordingley puzzle 85

White to play and win

(a nice one, to explore)

Solution

I enjoyed this one. The first move is obvious, 1 Ng5; but the second moves after black's two alternative defences are not. First, I quickly found (1…Nf8) 2 Nh7!; a motif I had seen before. Not immediately mating, but white gets an overwhelming advantage, and moves such as …Qc1 don't lead to unfortunate back rank mates, with Rge3 being both a defending and improving move. In the game, black played 1…Nf8.

Black's other defence, 1…h6, was a harder nut to crack. I kept looking at 2 Nf7 but I felt black could hold the end position after 2…Kf7 3 e6+ Kg8 4 ed Rd7. So, not for the first time, reverse the moves, playing 2 e6!; in fact, 'reverse the moves' was a rationalisation after I found it: instead, I used a maxim of CJS Purdy, the precise words of which I forget, but along the lines of 'ignore for a moment a threat;what would you rather do if the threat were ignored'. Here, the doubled rooks on the e file give white just enough to prosecute the attack but only to a draw (or so I thought) if (after 2 e6) black plays 2…hg: 3 ef+ Kf7 (Kf8 4 Qh8+ and 5 Re7+) 4 Re7+ Kg6 5 Rg7+! Kg7 6 Qg5+ perpetual. The threat of back rank mate prevents white from succeeding.

In fact, Houdini shows me that after 4…Kg6 5 Qd4!! is decisive- and is the only decisive move. Stockfish, on my iPad, couldn't find it (at least in the time I gave it to think). The position after 5 Qd4! is rich, and I plan to explore it further.

Cordingley gives 1…Nf8 as his main line, the move played, with his only mention of 1..h6 being ('Keres gives 2 e6 as the winning line against 1…h6', with no variations). In fact, Keres doesn't quite say this. I have a copy of his 'The Early Games of Paul Keres', translated by Harry Golombek, in which this game is included. He gives 1…Nf8 a ? saying that after 1…h6! 'Black could have still put up an obstinate resistance.' Keres finds 5 Qd4!! and the best line against it 5…Qc3!! 6 Bc2+!!; he shows a typical line which wins after 6 Bc2!! Keres prefers 4… Kg8, which I thought lost to 5 Qg5: his analysis, which I haven't checked yet, ends with 'White has some winning chances owing to his opponent's weakened king-side. From a glance at some of his lines, I suspect he is correct: black can hold on, and suffer.

I may well examine further this game, and blog about it separately, including improving the analysis posted below.

Posted with Blogsy