23 April 2017

Annotated Game #172: Light and Dark

This next tournament game is probably the best one of mine that illustrates the idea of weak-square complexes and how one can exploit them, which for Class players is a sometimes mysterious concept.  Here we have a clear light vs. dark situation on the board, with my opponent's pawns placed on dark squares, which have the effect of restricting his dark-square bishop, but more importantly leaving open the light squares to be dominated by my pieces.  This situation was evident by move 17 and demonstrated by the effectiveness of my centralized knight (these weaknesses aren't just for bishops to exploit).

Although even well into the middlegame my opponent either had a small advantage or at least equality, despite his weaknesses, I felt comfortable playing the position and was able to identify good ideas for making progress.  I also correctly identified many of the important positional ideas (including strong and weak squares) and found dynamic moves like the (temporary) pawn sacrifice idea on move 19.  The turning point of the game was the sequence that began on move 23, which involved my finding some unexpected intermediate moves and placed my opponent under significant pressure for the first time; this led him to err with 26...Rf7?!  Although not a losing move in itself, I was subsequently able to maintain the initiative for the rest of the game and win an interesting, dynamic minor piece endgame.  Even considering some weaker play in the opening and early middlegame, I feel this game serves to highlight some of the signposts of progress that I have been making in strengthening my game.

ChessAdmin - Class C

Result: 1-0

[...] 1.c4 c5 2.¤f3 ¤f6 3.¤c3 ¤c6 Symmetrical Four Knights variation. 4.g3 e6 indicating my opponent is going to take a relatively cautious approach to the opening, at least early on. 5.¥g2 ¥e7 6.O-O O-O 7.d3 I thought for a while here on the best approach to take. The main alternative is d4 (and by far most often played), while b3 is also a possibility, with a double fianchetto position. 7...d5 8.cxd5 played to reduce Black's central pawn presence and make pressure from the Bg2 down the long diagonal more meaningful. 8...exd5 9.¥g5 in the English it's sometimes hard to know what to do with the dark-square bishop. I didn't see a future for it on the queenside and on f4 it could be harrassed by ...Nh5, so I picked g5. When playing this move, White has to be prepared to exchange it for the Nf6, so evaluating the effects of that piece trade is important. 9...d4 10.¥xf6 I had foreseen Black's last and considered that the resulting position was good for me, with the centralized knight vs. a locked-in Bf6. 10...¥xf6 11.¤e4 ¥e7³ objectively speaking, Black is a little better here. He has the two bishops and a small space advantage. That said, the position is relatively easy for me to play, with some clear ideas for making progress. 12.¦c1 done in the expectation of provoking Black's next move, which opens up the long diagonal for the Bg2. 12...b6 13.¤ed2 while the knight looked good in e4, it had no squares other than d2 open and could therefore be threatened by ...f5 (which Black plays shortly). Redeploying it gives it an equally good square and improves my piece coordination, is what I thought. 13...¦b8 my opponent appears concerned about the rook on the open long diagonal, so moves it. 14.a4 with the idea of preserving the c4 square for the knight, by restricting the ...b5 advance.
14.¤c4!? can in fact be played immediately to good effect. For example 14...b5?!15.¤fe5 taking advantage of the hanging Nc6 and the R+Q fork on the square. 15...¤xe5 16.¤xe5 ¥b7 17.¤c6 ¥xc6 18.¥xc6
14.a3!? would take away b4 from the Nc6, which is helpful in several variations.
14...f5 I felt that this move now was too loosening for Black's kingside. The knight is prevented from returning to e4, and the pawn then continues to f4 to try to weaken White's kingside pawn shield, but that does not appear to be sufficient reason for Black to weaken the a2-f8 diagonal and the light squares in general. (14...¥g4!?) 15.¤c4 f4 16.¤fe5 now my other knight gets into the action and releases the Bg2's power. 16...¤xe5?!
16...¤b4 is a significantly better choice, giving the knight an excellent outpost on b4.
17.¤xe5 the Ne5 now eyes the weak c6 square. I had thought that if Black exchanged the light-squared bishop for the knight (for example after trying ...Bb7, which I was thinking of following by playing the Nc6 fork) then that would leave me with a significantly positive imbalance between the remaining minor pieces (my light-square vs. Black's dark-square bishop). 17...£d6 the best option for Black, removing the queen from the fork and centralizing it.
17...¥b7? would in fact have been a significant blunder, but for other reasons: 18.£b3+!18...¢h8 19.¤f7+ ¦xf7 20.£xf7+⁠−
18.¤c6 now an exchange is not forced, but the Nc6 still causes Black difficulties. 18...¦b7 19.b4 I felt that this was necessary to energize my position and use my pieces most effectively, particularly the Rc1 (which is not otherwise playing). Komodo agrees. 19...¦c7 Black passes up the (temporary) pawn sacrifice.
19...cxb4?!20.¦c4 I had spotted this idea, targeting Black's weak pawns on the 4th rank. 20...fxg3 21.hxg3 ¥f6 22.¤xb4² and White has a slight advantage due to better piece activity.
20.bxc5 bxc5 now the position is still equal, but I have nice pressure against the c-pawn and comfortable play on the queenside. 21.¤a5 fxg3 it's often difficult to decide which pawn recapture to make in this situation. I decided that the open f-file would benefit me more than Black, who does not have his rooks connected on the back rank, and that the resulting pawn formation would be a bit more solid, not offering Black any prospects of an attack down the h-file. The drawback of the text move, as I immediately realized, was that I lose control of the e3 square, so I had to watch that carefully. (The engine gives an assessment of equality to both pawn recaptures, incidentally). 22.fxg3 ¥g5 here my opponent evidently did not consider the intermediate moves I could play in response to the threat against the Rc1, which end up giving me the initiative. I felt this justified my decision to open the f-file. 23.£b3+ ¥e6 24.¦xf8+ forcing the recapture with the king, as the Be6 otherwise would be left undefended (deflection tactic against the Qd6). 24...¢xf8 25.£b8+ placing the queen on the back rank and pinning the Rc7. 25...£d8 my opponent thought for some time here and found the best reply. (25...¥c8?26.¦f1+ ¥f6 27.¥b7±) 26.¦f1+ ¦f7?! this allows me to win the a-pawn. (26...¢g8) 27.¦xf7+ ¥xf7 28.£xa7 Black has some compensation in the form of the two bishops heading into the endgame, so I only have a small advantage. When calculating the pawn capture, I also needed to be very careful about evaluating Black's next move, which is very trappy. 28...¥e3+ I had thought a good deal about this position prior to initiating the previous sequence, so was prepared. 29.¢h1 better than f1, although it gives the king no squares. Either way is fine for White, however, according to the engine. 29...£e7 30.£xe7+ at the time I was happy to enter the endgame with the advantage of a passed a-pawn, although I figured that combating the two bishops could make it a hard slog. At least with the queens off, I did not have to worry about mating threats. The engine evaluates keeping the queens on as significantly better for White, since the queen can more effectively shepherd the a-pawn forward. However, queen endgames are also very complex, so I think I made a decent practical decision in trading material. 30...¢xe7 31.¤c6+ ¢d6 32.a5 I had calculated this out prior to the knight move, as Black does not have sufficient time to capture the knight before the pawn queens. The idea is to block the Bf7 from getting over to defend, while the Be3 is also out of the action on the queenside. Now Black has to find an "only move" at this point to defend. 32...¥e8? a reasonable try, but not sufficient.
32...c4 is the only move that preserves equality for Black and is not necessarily easy to find (for humans). 33.dxc4
33.a6 c3 34.¤b4 ¢c5 35.a7 ¢xb4 36.a8=£ c2 as White cannot keep the pawn from queening. For example 37.£b8+ (37.£f8+ ¢c3 38.£xf7 c1=£+) 37...¢c3 38.£c7+ ¢d2
33...¥xc4 34.¥f3
33.a6 ¢c7 34.a7 by this point I knew that I would have to give up the a-pawn for Black's d-pawn, but was not sure when would be best. After some thought, I figured that it would be better to have Black's king a little further away. The engine disagrees.
34.¤xd4 makes the knight a much more threatening piece and introduces some tactical ideas. 34...¢b6 35.¤f5 ¥d4 I had seen this far and didn't consider it any better than the game continuation, but after 36.¤xd4 cxd4 37.¥b7+⁠− White has the easy winning strategy of activating his king and clearing away Black's d-pawn.
34...¢b7 35.¤xd4+ transforming the advantage of the passed a-pawn, by taking advantage of the discovered check. An example of a tactical trade, in this case the a-pawn for the d-pawn. 35...¢xa7 36.¤f5 ¥d4 I felt at the time that this was a losing move, giving away the benefits of the two bishops and clarifying my advantage. The engine is less harsh in its evaluation, not seeing the evaluation as any worse, although from a practical standpoint it made my mental task easier. 37.¤xd4 cxd4 38.¥e4 I thought for a while about this or Bd5, they are both good centralization moves. Since it provokes Black's next (unforced) error, I'm glad I went with it. 38...g6?+⁠− Now Black has made his kingside pawns vulnerable to penetration by my king and/or bishop. This was the actual losing move. (38...h6±) 39.¢g2 ¢b6 40.¢f3 the plan is very obvious for White here, to threaten the d4-pawn and tie Black's king to its defense, then go after the kingside pawns. 40...¢c5 41.¢f4 h6 42.h4 guarding g5 against a supported Black pawn advance 42...¥f7 43.¢e5 g5 44.hxg5 hxg5 45.g4 played as a prophylactic move, to keep Black's bishop from h5. 45...¥b3 with the idea of moving to d1. 46.¥f3 the safest route to victory. Now that Black can only move the king or bishop, eventually he will be put in zugzwang; my bishop protects both e2 and g4 and the king has full freedom. 46...¥d1 47.¢e4 I did this rather than move directly to e5 to have Black essentially lose a tempo with the bishop, although it's not truly necessary. 47...¥b3 48.¢f5 ¢b4 49.¢xg5 ¢c3 50.¢f4
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