Friday, 8 April 2016

Find the best move

Andrew Donnelly, who plays for Sudbury in Suffolk League Division 2 and for Bury St Edmunds in the Bury Area League, reached the position below on Wednesday in a match against Cambridge City's Ben Tarlow (155).   Andrew (Black, to play) was two pieces ahead but his king is misplaced, his bishop is pinned and the rook on h8 is useless, at least for the time being.   There is also potential for a White mate on d8 or e8.

Study the position for a few minutes and decide what move you, as Black, would make.   Andrew chose a move which won very quickly, but not because it was the best move; Ben followed up by a move that lost immediately.

Andrew played ... Bg4, attacking the White queen.   According to the computer, this is about the 10th best move!   Ben then played Qd8+??, and after ... Rxd8, Rxd8+   Ke7, White resigned as the rook on d8 is en prise after White takes the Black queen.

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The computer gives ... Qf6 as the best move.   Did you find it?

Andrew's own comments on this position are as follows:

"I've looked at this long and hard as I did whilst playing.   The position is complex with multiple threats from both sides.   From my perspective all I could see was queen takes on c6 threatening the rook on a8 and also threatening the knight on c3 which is already being attacked by the rook on d3.   It also attacks the e8 square potentially leading to a mate.   My rook on h8 is out of the game and looks like easy pickings if there is a check on the back rank.   Couple this with the threat of the rook coming to e3, threatening both the queen and e8 and the bishop on e2 and still attacking the knight on d3, I am in meltdown mode.   I looked at bringing the knight back to d5 to stop the rook coming to e3 but that surely loses to queen takes c6, rook d8, queen c5 check, king g8, and then pawn c4!   All I could think of at the time was bishop to g4 and exchange to a rook and knight with pawns v a rook and pawns.   A relatively simple win.

Now with a computer on board and no human pressure, queen to f6 tells us that I keep the two piece advantage and have a +7.1 advantage.   I never even looked at this but human pressure works both ways.   With my attempt to simplify down to a +2.8 advantage, I threaten the back rank mate if the queen takes the bishop.   An obvious bluff but my opponent being human sees the vulnerable rook on h8 and checks on d8, thinking that after Queen checks on d8, rook takes back, rook takes check, king moves to e7, and rook takes queen check on e5, he can pick up the h8 rook but of course I can take the rook on e8, game over.

Again I would emphasise that I looked at this long and hard and my opponent was not some patzer; he is a good player who despite being a couple of pieces down had a real chance of winning the game, (see my other preferred move of knight d5??).   I suppose my point is that had I made the best computer move, the game could have continued for many more moves; playing a more human move finished it two moves later!"


11 comments:

  1. I came up with Bg4 too. Must be natural for us to simplify, where maybe a computer is looking for the top points scoring move.
    T.L

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  2. looking at this whilst catching up with the sports news on TV I thought, I can do this, men can multi task as well!
    My first thought was Qd6 with idea of swapping off Q's and if Qf5 then Bxd3 hitting Q again. I then saw to my horror there was a gaping hole in this line, Rxd6 ruins it! Perhaps a rethink on multi tasking was required....
    Rb8 was next, getting R away from Qxc6 threats and eyeing up a back rank mate. Unfortunately it doesn't carry any threat nor help to improve the prospects of it's colleague trapped on h8. Also white doesn't have to do anything, g3 or h3 giving his K air puts the ball back in black's court, hmm still not satisfied.
    Thankfully the golf has appeared on screen and I can now concentrate exclusively on the problem in hand!
    g6 is my next thought and I like this, it prevents any nasty back rank tricks from white, allowing the R's to be connected with Kg7 so that Qxc6 is not a problem. yes that would be my candidate move. How does that compare to Qf6 in the list of moves?
    I didn't look at Bg4 as you indicated it wasn't good. To be honest I doubt I would have given it much consideration during the game as it doesn't do anything to relieve bank rank tricks. g6 solves this and allows black to move on to converting his material supremacy.

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  5. Let's try again, after g6, Qxc6,Kg7,Rxc3 with the bishop looking precarious

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  6. I calculated and would have played g6 too. I saw that after g6 Qxc6 Kg7 Rxc3 Qd4

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  7. There is also Rae8 which sets a trap, Re3 being answered by Qb2 Rxe8 Bb5!!

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    Replies
    1. Yes it does. Ian means ...Rae8 instead of ...Qd4 in Silas's line, not in the original position.

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    2. I still can't understand this. The queen can't go to b2 because the knight is still on c3.

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  8. Bob,
    Anonymous is correct, my last comment continues Silas's analysis and point out that after g6 Qxc6 Kg7 Rxc3 black has the option of Rae8 as well as Silas's suggestion of Qd4.
    After Rae8 if white tries to win material with Re3 (moving from c3!) and thus allowing Qb2 Rxe8 and Bb5 springs the trap and black wins.
    All clear now?!

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