Komodo – Stockfish (TCEC Season 6, Stage 3) annotated by GM Davorin Kuljasevic

fb_tcec_cover_02Thoresen Chess Engines Competition (TCEC) Season 6 – Stage 3 is in progress.

Eight engines are competing in a quad round robin format and only the top 4 will move on to Stage 4, while the rest are out of TCEC for the current season.

Stockfish 4 (3135), modification 080414 leads the third Stage of TCEC – Season 6 with 10.5/15, followed by Komodo 1217 (3133) with 10/15.

Houdini 4 (3132) is third with 9.5/15, despite its unexpected loss versus Gull A228 (3021) in the fifteenth round of TCEC Season 6 – Stage 3.

Standings after 15 rounds:
1. Stockfish 080414 3135 10.5
2. Komodo 1217 3133 10.0
3. Houdini 4 3132 9.5
4. Critter 1.6a 3031 7.5
5. Rybka 4.1 3087 7.5
6. Gull A228 3021 7.0
7. Fire 3.1 3096 5.5
8. Shredder 12 2921 2.5

One of the most interesting encounters of the third Stage was the battle between Komodo and Stockfish in the first round of TCEC Season 6 – Stage 3. We bring you the game, annotated in-depth by GM Davorin Kuljasevic.

Komodo (3133) – Stockfish (3135) [B98]
TCEC Season 6 – Stage 3 (1), 10.04.2014
[GM Davorin Kuljasevic]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bg5 e6 7.f4 [A well-known position in the Najdorf. Stockfish team opts for the most common continuation.]

7…Be7 [The famous "Poisoned pawn" variation starts with 7...Qb6; while 7...h6 8.Bh4 Qb6 has been the most recent try by Black, with Najdorf experts such as Vachier-Lagrave, Dominguez, and Wojtaszek giving it a shot.]

8.Qf3 h6 [This move is relatively rare compared to the main line 8...Qc7 9.0–0–0 Nbd7 10.g4 b5 etc.]

9.Bh4 0–0?! [Now, this is a real sideline, and a dubious one at that. Black does not usually castle this early in Bg5 Najdorf, at least not until he has had some counterplay going on the queenside. The presence of the pawn on h6 makes this idea even more suspicious as now White can open up Black's kingside with the usual g4–g5 thrust even faster.]

[Black have tried here 9...Qc7; 9...Nbd7; and even 9...g5 with acceptable results.]

10.0–0–0 Bd7 [This Rauzer-like development is in fact more appropriate here. Black needs to challenge White in the centre immediately as otherwise he might get crushed on the kingside.]

[More in Najdorf-style would be 10...Qc7 which was played in the only two "decent" games I was able to find in my database. One was between two computers in a Freestyle tournament, while another one was between two humans; however, both finished badly for Black, especially the human one. 11.g4 b5 (11...Nbd7 12.g5 hxg5 13.Bxg5 b5 14.Rg1 b4 15.Nd5! A typical, but very powerful blow. 15...exd5 16.Nf5 Nc5 17.Nxg7 dxe4 18.Bxf6!!
18...exf3 19.Ne6+! Covers the c8 bishop before delivering the final strike. 19...Kh7 20.Rd5 with inevitable mate to follow in the game 1–0 (20) Daurelle,H (2263)-Benitah,Y (2421) L'Estartit 2007) 12.a3 Bb7 13.g5 hxg5 14.Bxg5 Nc6 15.Nxc6 Bxc6 16.Rg1 g6 17.Bd3 Black is already in trouble. His kingside is very vulnerable and he has no counterplay on other parts of the board. 17...d5 18.Bxf6 Bxf6 19.exd5 Bb7 20.Bxg6! It's the right time to destroy the pawn shield around Black's king. 20...fxg6 21.Rxg6+ Bg7 22.Rdg1 Rf7 23.Qf2!
[24.Nxd5 exd5 25.f5 Qa7 26.Qg2 Kf8 27.Qxd5 Qb7 28.Qxb7 Rxb7 29.f6 and Black soon resigned in 1–0 (34) Intagrand (2638)-Hoshad (2486) INT 2007. Another Sicilian nightmare for Black.]

11.Bf2!? [I like this cautious move in young Karpov's style by Komodo.]

[11.g4 would be the most straightforward approach, but then 11...Nc6 would force White knight to abandon its central post 12.Nb3 Here I found two correspodence games, White winning both of them pretty convincingly, although Black could arguably defend better. (The hasty exchange 12.Nxc6?! Bxc6 would only help Black to put his light-squared bishop on a terrific diagonal.) 12...Qc7 (12...Rc8 13.Rg1 b5 14.g5 hxg5 15.Bxg5 b4 16.e5 dxe5 17.Bh6 g6 18.Ne4 Nd4 19.Nxd4 exd4 20.Bd3 Bc6 21.Nxf6+ Bxf6 22.Qg4 Be8 23.h4 Bg7 24.Bxg7 Kxg7 25.h5 f5 26.Qe2 Qd6 27.Kb1 a5 28.Bb5 Bxb5 29.Qxb5 Rf6 30.Qxa5 Qxf4 31.Qxb4 Rc7 32.Qb8 Qd6 33.Rxd4 Qc5 34.c3 e5 35.Rdd1 Qb6 36.Qe8 Qe6 37.Qd8 Re7 38.Rxg6+ Rxg6 39.hxg6 f4 40.Kc1 Re8 41.Qc7+ Re7 42.Qc5 Qf6 43.b4 Kxg6 44.b5 f3 45.b6 1–0 (45) Langer,R (2223)-Nichols,S (2240) Lechenicher SchachServer 2011) 13.Rg1 b5 14.g5 hxg5 15.Bxg5 Rfc8 16.Qg2 Ne8 17.Bh6 Bf8 18.f5 b4 19.fxe6 Bxe6 20.Nd5 Bxd5 21.exd5 Ne5 22.Nd4 g6 23.Bxf8 Kxf8 24.Bd3 Qb6 25.Nc6 Nf6 26.Nxe5 Qe3+ 27.Kb1 Qxe5 28.Bxg6 Rc4 29.h3 fxg6 30.Qxg6 Ke7 31.Qg7+ Kd8 32.Rde1 Qf5 33.Qf7 1–0 (33) Joao,N (2443)-Cody,P (2294) ICCF email 2000]

11…Nc6 12.Rg1 [This preparatory move is necessary]

[as 12.g4? runs into 12...Nxd4 13.Bxd4 e5! and suddenly White loses material.]

12…b5 13.e5 [The proper reaction to Black's previous move. For one, c6 knight has lost its foothold after b7–b5 and Nxc6 is threathening.]

[Secondly, 13.g4?! would now be too slow since 13...b4 14.Nce2 d5 allows Black serious counterplay. Black is usually happy if he can push d6–d5 in the Sicilian.]

13…Nxd4 14.Bxd4 dxe5 15.fxe5 Nd5 [Black is ready to except a worse, but solid position.]

[Alternatively, he could go for a Scheveningen-like maneouvre 15...Ne8 when he can defend against the battery Bd3, Qe4 with g6 and Ng7. However, White doesn't risk much there either and probably has better attacking prospects compared to the game.]

16.Nxd5 exd5 17.Bd3 [Greedy 17.Qxd5? would be a mistake in the view of 17...Bg4! 18.Qe4 (18.Qxd8 loses immediately 18...Raxd8 19.Rd3 Bg5+ 20.Kb1 Bf5 21.Rd1 Rxd4 22.Rxd4 Be3) 18...Bxd1 19.Bd3 g6 20.Rxd1 Qd7 and White doesn't have sufficient compensation for the exchange.]

17…Be6 18.Kb1


[We can sum up the opening results as favorable for White. He has achieved a better position without any risk. Black can be partly satisfied as he has avoided immediate disaster, which seems to be more or less the typical scenario in this dubiuos line (9...0–0?!)]

18…Rb8 19.g4 g6 [This prophylaxis is probably necessary in order to avoid a direct assault, for instance]

[in case of 19...Rc8 White wins with the the help of double pawn-sacrifice: 20.g5!


20...Bxg5 (20...hxg5 21.Qh5) 21.h4 Bxh4 22.Be3 and Black is defenceless against all threats. 22...Bg5 (22...Kh8 23.Qh5) 23.Bxg5 hxg5 24.Qh5; 19...Bg5 would be only a temporary solution. White would then continue to mount the pressure with 20.Bf2 followed by Qg3, h4 etc.]

20.Rgf1 [Komodo continues on a positional course.]

[However, I think it was possible to attack as well with 20.g5!? h5 might be the defence Stockfish had in mind. Still I very much prefer white after (Now 20...hxg5 looks suspicious again due to 21.h4! Kg7 (21...g4 22.Rxg4 Bxg4 23.Qxg4 Qc8 doesn't stop White's attack. After 24.Qf4 he will break through with h5 etc.) 22.h5! (22.hxg5?! is really not in the spirit of this position. Black consolidates after 22...Rh8) 22...gxh5 23.Qxh5 Rh8 24.Qf3 and despite being a pawn down, it's still White that is calling all the shots.) 21.Rdf1 Qc7 22.Qe3 Qc6 23.Rf6 and Black has to show great precision in defence.]

20…Rc8 21.h3 [Black's position is passive, but quite solid - it's not simple for White to break through - so we will witness some light maneouvering until the position clears up a bit.]

21…Re8 22.Bf5 [Of course, the bishop is immune.]

22…Rf8 [22...gxf5?? 23.gxf5 would lead to a quick checkmate along the g-file.]

23.a3 [23.Bxe6?! is premature, since Black is safe in the French-like structure after 23...fxe6 24.Qd3 Kg7]

23…Kh7 24.Bd3 Rb8 25.Qg3 b4 [A controversial decision. Of course, Black is looking to get some counterplay, but generally opening up the position favors the side that holds the initiative. Strictly strategically speaking, White should be happy with this pawn exchange as in such positions he is usually the one that tries to push a2–a4 in order to create a pawn weakness on Black's queenside (either b5 or a6). With his last move Black has done this job for him and now he always needs to be careful about the a-pawn, which could prove especially weak in all sorts of endgames.]

[It might have been more prudent for him to sit tight with a neutral move such as 25...Bh4 but then again, how many people (and engines!) would forego an opportunity to finally get some counterplay?]

26.axb4 Rxb4 27.Bf5!


We’ve already seen this move, but in this case it is more effective. White will now play on both sides of the board so he needs to clear the third rank for his heavy pieces and create some weaknesses on the kingside. This move is perfect for both ends.]

27…Qc8 28.Bxe6 fxe6 [The right positional decision.]

[The alternative 28...Qxe6 seems to be playable as well. However, the queen is very passive on e6, as well as the rook on f8. The game can continue something like this 29.h4 a5 30.h5 g5 31.Qd3+ Kg8 32.Rf5 a4 33.Rdf1 with a difficult position for Black. Now any time Black moves his queen from e6, White can sacrifice the e-pawn to open up his bishop with dangerous threats to Black king. It should also be noted that 33...a3 is not dangerous due to 34.b3 and White will pick up the weak a-pawn later on.]

29.Rxf8 Qxf8 30.Qd3 Qa8 31.Rf1 Kg7 [Black succeeded in trading off its passive rook for white's attacking one. However, white initiative still hasn't died as he finds new ways to attack the king.]

32.Qe3 Rb8 33.Rf6! [Looks scary, but Stockfish finds a cold-blooded defence.]

33…Qc6! [Taking the exchange 33...Bxf6 34.exf6+ Kh7 leads to a strong initiative for White after 35.Qxe6 Qb7 36.h4 etc.]

34.Qf2 Rb7 35.Rf7+ Kg8 [and White has to retreat.]

36.Rf3 Rb8 37.b3 Qb5 [Preparing a6–a5,]

[since 37...a5 drops the pawn to 38.Qd2]

38.Bc3!? [Komodo is just as resourceful.]

38…g5 [Now 38...a5 doesn't work because of 39.Qa7]

39.Qe3 Ra8?


An obvious mistake, although it is less obvious that it is the losing one! Black is playing for the attack too stubbornly,]

[when it should have thought about safety. Why not 39...Rf8 ? After the inevitable rook exchange, 40.Rxf8+ (In this case 40.Rf6 is not as dangerous as in the game since Black has 40...Bxf6 41.exf6 Rxf6! 42.Qe5 (42.Bxf6 Qf1+ 43.Ka2 Qxf6 is just a draw.) 42...Rf1+ (Black is OK even after the pedestrian 42...Qf1+ 43.Kb2 Kf7) 43.Kb2 Qd7 44.Qh8+ Kf7 45.Qxh6 d4 and White should better hold a perpetual.) 40...Kxf8 White would have a small plus in the endgame, but it should be nothing serious.]

40.Rf6! [For the second time in the game, Komodo goes for a recurring sacrificial motive. This time around, Black has to accept the sacrifice.]

40…Bxf6 41.exf6 Kf7 [Unfortunately for Black, 41...Qc6 42.h4 Rc8 fails to 43.Qd3! Qe8 44.hxg5 Rxc3 45.Qxc3 hxg5 46.Qe5 Kf7 47.Qxg5 Qh8 48.Qe5! and White is winning using the fact that the pawn endgame after 48...Qxf6 49.Qxf6+ Kxf6 50.c4 is winning.]

42.h4 Qb8 43.Qd3!!


The key move! This position is very reminiscent of Carlsen-Caruana game from the Zurich chess tournament two months ago, which Carlsen won in a very nice style after sacrificing the exchange in a similar fashion. Maybe Komodo was inspired by that game? :)]

[Stockfish was undoubtedly expecting 43.hxg5 hxg5 44.Qxg5 when 44...Qg8 45.Qf4 a5 46.g5 a4 should give him enough counterplay.]

43…Qg8 44.h5!


Another quiet move with great impact. Now the point of last two moves becomes obvious – White has basically stalemated Black queen.]

44…Ra7 [Black's position is already beyond saving.]

[44...Ke8 doesn't help. White demonstrates his winning plan 45.Be5 Qf7 46.Qg6! the queen exchange is hopeless, so White continues to pick up kingside pawns, winning easily as well.; The desperado attempt 44...a5 45.Be5 a4 runs into the counterattack 46.c4! axb3 47.cxd5 and it is Black who is about to get checkmated or lose a significant amount of material.]

45.Be5 Rd7 [Basically resigning, but there was nothing better.]

[If Black sits with 45...Kf8 46.Kc1 Kf7 White pulls out another ace out of his pocket 47.c4! dxc4 48.bxc4 and the c-pawn's march will decide the game.]

46.Qxa6 Qf8 47.Qd3 Ke8 48.Qb5 Qf7 49.Kb2 Kf8 50.Qa6 Ke8 51.Qc6 [A little game of cat-and-mouse before White converts the advantage.]

51…Kf8 52.Bd6+ Kg8 53.Qa8+ Kh7 54.Be5 Rb7 55.Qa5 Kg8 56.Qc3 Rd7 57.Qd3 [White has finally achieved a winning position. There is no defence against Qg6.]

57…d4 58.Qg6+ Kf8 59.Qxh6+ Ke8 60.Qxg5 Rd5 61.Qf4 [A very nice positional game by Komodo. Stockfish defended tenaciously, but it overestimated its chances in the very end and was punished swiftly.]

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