Collapsing barricades

31 October 2020

9:00 AM

31 October 2020

9:00 AM

Geometry shmometry. The pirouette of a knight may be pleasing to the eye, but sometimes what I really crave is a demolition. I don’t mean a smash-and-grab king hunt. I want to see a crumbling edifice, a colossal concrete barrier wilting beneath a torrent of water, as in The Dam Busters. On the chessboard, diagonal chains of pawns are our barriers: daunting, manmade and ostensibly impermeable.

Aron Nimzowitsch theorised in My System that pawn chains should be attacked at their base. Sound strategy, but when the base lies beyond reach, a more drastic bombardment can be called for, such as that which occurred in a recent game between two computers.

Leela Chess Zero has been hunkering down since the opening, and Stockfish has lain siege.
We join the game at move 150(!) – see left of diagram.

Stockfish–Leela Chess Zero
TCEC Season 19, Game 60, October 2020

150 Qh5!! An astonishing blow. Stockfish offers a whole queen to breach Black’s kingside fortification. 150…gxh5 151 Rg7+ Ke8 152 Rxh7 Kd8 153 Rgg7 Both rooks gush into Black’s position. The immediate threat is 154 Rxe7 Qxe7 155 Nxc6+ Na8 154 Rh8+ Kc7 155 Rhg8! Black is impotent against the advance h6-h7-h8=Q. Ra4 156 h7 Rxa5 157 h8=Q Nb6 There is nothing better. 158 Re8 Nc8 159 Rxc8+ Qxc8 160 Rxe7+ Kb8 161 Qxc8+ Kxc8 162 Rxa7 White emerges a bishop ahead. Kd8 163 Rxa6 Rxa6 164 Bxa6 h4 Black resigns

This was reminiscent of another famous breakthrough – see right of diagram.

Stefan Brzozka–David Bronstein
USSR, 1963

The locked pawn structure seems to promise a draw, even after White loses rook for knight. But Bronstein breached the defence:

46…Ra6! Ingenious. White must acquiesce to the following sequence: 47 Rd1 Nxd5+ 48 Rxd5 Now, Bb1-c2 would secure the fortress, but Rxb3+!! 49 Kxb3 49 axb3 a2 50 Bxa2 Rxa2 51 Rd2 Ra1! White’s weak pawns on g3, e3 and b3 promise a thankless defence. Rb6+ 50 Kc2 Rb2+ 51 Kc1 Re2 Once again, White’s structure crumbles bit by bit. 52 Rd1 Rxe3 53 Rg1 Rc3+ 54 Kd2 Rxc4 55 Bc2 d5 With three connected passed pawns for the bishop, White’s position is almost hopeless in practice. 56 Rb1 d4 57 Bd1 57 Kd1 was a better try, hoping for Rc3 58 Rb3! Rc3 58 Rb3 e3+ 59 Ke2 Rc1 60 Rxa3 c4 61 Ra7+ Kd6 62 Ba4 Rh1 63 Rd7+ Kc5 64 Rc7+ Kb4 65 a3+ Kc3 66 Bb5 Rh2+ 67 Kf1 d3 68 Rxc4+ Kb2 69 Kg1 e2 70 Kxh2 e1=Q White resigns

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