Black to move (Stefanova – Shirov 2005)
r3rq1k/8/p2p3p/P1pPnp1P/1p3Q2/5PNR/1PP2K2/R7 b – - 0 29
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Evaluation
The first thing I did was to evaluate this position, and I gave it the following evaluation: Material =, King Safety +/=, Activity =/+, Pawn Structure =. So the game in my opinon is even. (When I gave it to Fritz 10 he sees it as -+ (- 1.61 with Black winning) and Rybka sees it as -1.19).
Threats and Opportunities
I then looked for threats and opportunities in this position, and I found that White was threatening to win Black’s f5 pawn with Qxf5.
Candidate Move Selection
After performing the threat analysis I looked for candidate moves, and this is the order in which I found my 4 candidates: 1…Re7, 1…Kh7, 1…b3, 1…Ng4+. The first two candidates are defensive, trying to deal with the potential threat of Qxf5, and the last two are aggressive candidates.
Analysis
I then began analyzing the most aggressive candidate based on CCT (checks, captures and threats), in this case …Ng4 would be the most aggressive since it starts with check, below is my analysis:
Candidate 1 …Ng4+
29…Ng4+ 30.fxg4 30…fxg4 31.Qxf8+ Rxf8+ 32.Kg2 gxh3+ 33.Kxh3 This line is good for black since he wins the exchange, so taking with 2.cxb3 is not good for White so I analyzed another line in which White does not take to see if …Ng4+ stands up. [30.Kg2 Not taking keeps White in the game. 30...Ne5 coming back to the same position is not good for Black, since White's King is now safer on g2. At this point I figured that if White didn't take I would wind up in this position, and I stoped analyzing this line, and I jumped to the ...b3 line which was the 2nd most aggressive candidate I had selected. The problem is that 30...Ne3+ should have been considered as a mainline, and I did not see this knight check, with the rook defending it. (30...Ne3+ I did not analyze this subvariation, but it was much better than 30...Ne5 which I did analyze and caused me to jump to another line. 31.Kh1 Nxc2 32.Rc1 Nd4 Black wins a pawn, and defends g5.) ; Rybka 2.3.1 32-bit : 30.Kg1 Ne3 31.Re1 Nxd5 32.Rxe8 Nxf4 33.Rxf8+ Rxf8 34.Rh2 d5 35.Kf2 Kg7 -0.91/12 ]
Candidate # 2 …b3
[29...b3 This is the second line I analyzed. 30.Qxf5 So, I analyzed another line other than 30. cxb3, the problem is that this line is not the best line for White. (30.cxb3 Nd3+ Taking my b3 pawn is bad because of this fork.) 30...Qxf5 31.Nxf5 bxc2 32.Rc1 (32.Ne3 Nd3+ At this point I decided to chose this line.) 32...Nd3+ ; Rybka 2.3.1 32-bit : 29...b3 30.Qd2 bxc2 31.Qxc2 Ng4+ 32.Kg1 Ne3 33.Qd2 f4 34.Ne4 Re5 -1.27/11 ]
Lessons Learned
My evaluation was off by a pawn, Rybka and Fritz think that Black is at least ahead one pawn, while I thought the position was even, so I need to work on my evaluation skills. I was happy with my candidate move selection, and the order in which I began analyzing (the most aggressive moves first). Out of the 4 candidates I only had to analyze 2 and both were the best moves. In the analysis department, I am missing the best response when I calculate variations or I am not analyzing all possible oppnent candidate moves. I need to use the same candidate move criteria fwhen looking for or my opponent responses, but I have a feeling it also has to do with board visualization. Even though I picked an appropriate candidate, the logic for selecting it was flawed and incomplete. The analysis for …b3 did not take into account White’s best responses and much was left to chance by selecting it. I need to be more thorough when analyzing and I also have to attempt to evaluate the position at the end of the my analysis (which I did not do). The line played in the game was …Ng4+!, while Fritz 10 and Rybka prefer …b3.
