Sunday, 2 June 2019

049. Queen vs. Rook and Pawn

White: Ares777 - all-play-all tournament,, 2018

An opening sacrifice (8...0-0!?) – first seen in G.Sanakoev-J.Boey, 10th World Correspondence Championship 1978 – gave me good play for a pawn in the early middlegame, which developed successively into a strong initiative, a material advantage, and (after 47...h4!) a winning endgame with queen vs. rook and pawn.

The Shredder endgame database gives this as mate in 50. I spent a long time trying to understand why this is so, searching MegaBase for similar positions, and getting my endgame books down from the shelf.

GM Karsten Müller & IM Frank Lamprecht (Fundamental Chess Endings, Gambit 2001) write: “If the pawn is on its original square or if it is a knight's pawn the position is drawn, as long as the attacking king is cut off and can't get behind the pawn.”

GM Efstratios Grivas (Practical Endgame Play, Everyman 2008) writes more expansively:
“(...) provided that the defending king and rook are close to the pawn and that the opponent's king cannot attack from behind. The basic rules are:
1. With a central (c, d, e and f) pawn, it's a draw if the pawn is on the second, sixth or seventh ranks, but otherwise the queen wins.
2. With a b- or g-pawn, it's always a draw.
3. With a rook pawn, it's a draw if the pawn is on the third or seventh rank, but otherwise the queen wins.”

And yet Shredder says I'm winning. Well, the authors are not wrong in what they say about the g-pawn, since they give the necessary proviso: if the attacking king cannot get behind the pawn. But it certainly doesn't look as if it can from the diagram.

The crucial stages are as follows:
  • First of all, 48...Qf2+! 49 Kh3 Qg1 threatens mate, so the rook has to drive the black king out and across the f-file (50 Rg4+ Kf5 51 Rf4+ Ke5).
  • Then (after 52 Kh4 Qh2+ 53 Kg4) the passing move 53...Qh1! creates a sort of zugzwang, in that White has to weaken his fortress slightly. In particular, if he moves the rook on the f-file (which offers the longest defence), either immediately or after 54 Kg5 Qh3 (seeing that 55 g4? Qe3 wins at once), the black king will advance up the board.
  • Then the queen returns down the board to hassle the white king from in front. Eventually, the rook has to give up control of the f-file, allowing the black king across and behind the pawn.
  • Black can then win the pawn, and then win with queen vs. rook.

The first three points above are exemplified in a superb endgame by the Czech master Emil Richter. From the position after 53...Qh1!, play continued 54 Rf2 Ke4 55 Re2+ Kd3 56 Rf2 Ke3 57 Rf4 Qb7 58 Kg5 Qg7+ 59 Kh4 Qh6+ 60 Kg4 Ke2 61 Rf5 Qg6+ 62 Kf4 Kf2 63 g4 Qd6+ 64 Kg5+ Kg3 65 Kh5 Qd7 66 Kg5? (making it easy) 66...Qg7+ and "White" resigned. I've put White in inverted commas there, because the moves were actually 76 Qh8! through to 89 Qg2+ and 1-0 Em.Richter-G.Stoltz, Karlovy Vary 1948, since the colours were reversed.

My game followed V.Burmakin-V.Lazarev, Werfen 1993, with 55...Qc1+! being a critical improvement. Black has to prevent the g-pawn from advancing freely. In the final position (where I claimed the game on time), White can in fact play 57 g4, but then the annoying pin on the rook means he has to waste moves with his king, allowing Black to get round behind; e.g. 57...Qd2 58 Kf5 Ke3 59 Kg5 Qd8+ 60 Rf6 Ke4 61 Kg6 Qg8+ 62 Kh5 Qh7+ 63 Kg5 Qg7+ 64 Rg6 Qe5+ 65 Kh6 Qe7 66 g5 Kf5 67 Rg7 Qf8 68 Kh7 Qa8 69 Rg6 Qh1+ 70 Kg7 Qh2 etc.

Incidentally, the Lomonosov tablebases show that the win can be considerably shortened by refusing the a-pawn on move 39. Apparently, 39...Qxa4 (its sixth choice) is mate in 59, whereas 39...Qe3! and 39...Qf7! are both mate in 37. I rejected those for two reasons:
1. White could have forced the game position by playing 39 Rf2 first.
2. Why on earth would Black refuse the pawn? I'd never refuse the pawn over the board.

Except that now I might. The a-pawn is not going anywhere. Yes, White can defend it with the rook, forcing the queen to blockade it for the moment. But when the black h-pawn comes up the board, White will then have to take it with the g-pawn, giving him two rook's pawns – until one of them drops off, after which he'll only have a rook's pawn, and on an unfavourable square, making the win that much more straightforward.

Damn, I love endgames.

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