Chess Skills: Decisive Advantage?

13 February 2017

Decisive Advantage?

When do you resign? Losing an exchange should not be sufficient cause for resignation. But, what if you are down an exchange and your opponent is rated 300 Elo higher? What if you are down an exchange and your position is passive?

Going through the games in Branko Tadic and Goran Arsovic, Encyclopedia of Chess Miniatures (2015), I came across a game where it seemed that Black might have resigned a little early. It did seem as though White's play from the position at the end of the game was relatively straightforward and that Black was consigned to passive defense. Even so, most players would play on in such a position.

I searched for the game online and found that 2700chess.com has it. That site offered me the option of playing against the computer from the final position. Of course, I could easily set up the game on my computer and play Stockfish 7, but it was coffee time. While drinking my coffee, I like to sit in the living room with my dogs and use my iPad. The strongest chess engine setting that seemed available to me on the website was 2200--good enough that it will exploit tactical blunders or force a draw if the opportunity arises.

Komarov,Dimitri (2541) -- Bogdanov,Emil (2249) [E12]
FRA-chT N1 Drancy (3), 06.02.2005

1.d4 Nf6 2.Nf3 e6 3.c4 b6 4.a3 Bb7 5.Nc3 Be7 6.d5 0–0 7.g3 d6 8.Bg2 Re8 9.0–0 Bf8 10.b4 c6 11.Nd4 cxd5 12.cxd5 Nxd5 13.Nxd5 Bxd5 14.Nxe6 fxe6 15.Bxd5 Nd7 16.Bxa8 Qxa8 17.Bb2 Be7 18.Rc1 1-0

Black to move

After playing against the computer, my coffee was finished. I went to my computer, entered the moves into a database, and ran quick analysis with Stockfish 7 at full strength to observe what I or the weakened engine on 2700chess.com might have missed.

Stripes,J -- Stockfish (2200 strength)
2700chess.com

18...b5 19.Qb3 Bf6 20.Rc7

Stockfish seems to prefer that I play Rc7 before Qb3. 19.Qd3 was also an option. All of these moves offer white an advantage of 2.5+, a little more than the material difference.

20...Ne5 21.Bxe5

I did not want this knight plugging the c-file.

21...Bxe5 22.Qe3 Qd5 23.Qxa7 Bb2

White to move

One improvement Stockfish 7 noted up to this point was that I might have played Rfc1 on any of several moves. Now, Black prevents bringing the second rook to the open file.

24.Qb7

Is it beneficial to exchange queens when ahead a rook for a bishop, and with more active rooks? I thought so here.

24...Qe5 25.Re7

At first, Stockfish prefers 25.e3, but as it examines the position longer, it likes my move almost as much as its first choice.

25...Rxe7 26.Qxe7

Threatening checkmate in one.

26...h6

26...h5 might be a little better.

27.Rb1

This move drops the computer's assessment of White's advantage from near 5.0 to 3.5. Even so, it seems that I have improved White's advantage from the end of Komarov -- Bogdanov.

Stockfish likes 27.Qe8+ Kh7 28.a4.

I did not look at this variation during the game. The central Black pawns had been my focus when considering why Bogdanov resigned.

27...Qxe2 28.Qxd6 Kh7

White to move

29.Rxb2!?

The point of my move 27. Giving back the exchange to enter a queen ending with only a one pawn advantage would normally seem the way to convert a win into a draw.

29...Qxb2 30.Qd3+ Kh8 31.h4?!

I had originally planned 31.Qxb5 Qb1+ 32.Kg2 Qe4+ but was not prepared to play 33.f3 Qc2+ 34.Kh3. This unplayed line is Stockfish 7's preference.

31...Qe5

White to move

My advantage has diminished to 1.27, but my confidence is now rooted in the observation that Black's queen can defend both e6 and b5 from relatively few squares.

32.Kg2 Kg8 33.Qf3 g6

Stockfish 7 sees this move as half a pawn worse than 33...g5. Was 33...g6 Black's critical error? It seems to me that I now have a third pawn for my queen to attack. How can Black defend everything?

34.Qb7 Qe2 35.Qb8+ Kg7 36.Qc7+ Kh8

White to move

37.Qd8+

37.Qf7 seems faster.

37...Kg7 38.Qe7+ Kg8 39.Qf6

Black to move

39...h5

39...Qe4+ at first seems to refute my plan to convert a queen ending 40.Kh2

a) 40...Qf5 41.Qxf5 exf5 42.Kg2 should be a simple win for White
b) 40...Qc2 41.Qxe6+ Kg7 42.Kg2 increases White's advantage to two pawns and weaknesses remain in the Black position.

40.Qxg6+ Kh8 41.Qf6+ Kh7 42.Qf3 Qe5 43.Qe3 Qd6

43...Qd5+ 44.f3 Qa2+ 45.Kh3 Qa1 complicates my task.

44.Qe4+

Black to move