Articles
Death By Accelerated Dragon

Death By Accelerated Dragon

Silman
| 33 | Amazing Games

N.N. (1770) - Vanilla Cokehead (1820), England 2012 [time controls: 30 moves in an hour and 15 minute blitz finish] 

1.e4 c5 2.Nc3

2.Nf3 g6 is known as the Hyper-Accelerated Dragon. Instead of playing 2...d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 g6, which is the Dragon, or 2...Nc6 3.d4 cxd4 4.Nxd4 g6, which is the Accelerated Dragon, Black holds off on ...Nc6 and prepares to financhetto his dark-squared Bishop as quickly as possible. But why avoid 2...Nc6? One reason is that some players simply don’t like to face 1.e4 c5 2.Nf3 Nc6 3.Bb5, which is called the Rossolimo Variation. Another reason is that 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6 5.c4 can be annoying (though some players aren’t worried about 5.c4 at all). An immediate 2...g6, though still allowing White c2-c4 options, also gives Black more aggressive ways of dealing with them. Of course, though 2...g6 ends any worries about the Rossolimo, and also offers Black ways to add a bit of zest to the Maroczy setups, it gives White some other options that wouldn’t normally be possible. 

Here’s a very tiny taste of the voluminous amounts of theory that’s out there after 2…g6: 

1.e4 c5 2.Nf3 g6 3.d4 Bg7 4.d5 d6 5.Nc3 Nf6 takes us into a Schmidt Benoni.

1.e4 c5 2.Nf3 g6 3.d4 Bg7 (3…cxd4 4.Nxd4 Bg7 avoids the Rossolimo but still allow s the Maroczy Bind) 4.Nc3 cxd4 takes us back into a pure Accelerated Dragon where Black has avoided the Rossolimo and Maroczy.

1.e4 c5 2.Nf3 g6 3.d4 Bg7 4.dxc5 is a sharp line. Alejandro Roman Moreno (2391) – G. Kacheishvili (2606) [B27], US Chess League Final Blitz 2009 continued, 4…Qa5+ 5.c3 Qxc5 6.Na3 d6 7.Nb5 a6 8.Be3 Qc6 9.Nfd4 Qd7 10.Na3 Qc7 11.Nc4 Nd7 12.a4 b6 13.Be2 Bb7 14.f3 Ngf6 15.0-0 0-0 16.Qd2 e5 17.Nc2 d5 18.exd5 Nxd5 (Black has a great game) 19.Bh6?? Bxh6 20.Qxh6 Nf4 and Black won quickly since any attempt to defend e2 results in …Nxe2 followed by …Qxc4.

1.e4 c5 2.Nf3 g6 3.c3 Bg7 (3…d5!? is also popular) 4.d4 cxd4 5.cxd4 d5 and now both 6.e5 and 6.exd5 have been shown to be fine for Black: 6.e5 (6.exd5 Nf6 7.Bb5+ Nbd7 8.d6 0-0!? [An interesting pawn sacrifice. More usual, and fully adequate, is 8…exd6 9.Qe2+ Qe7 10.Bf4 Qxe2+ 11.Bxe2 Ke7 12.Nc3 Nb6 13.0-0 h6 14.Nd2 Be6 15.Bf3 Nfd5 16.Nxd5+ Nxd5 17.Bg3 Rac8 18.Rfe1 Kd7 19.Ne4 Rc6 20.Nc3 Rxc3 21.bxc3 Nxc3 22.Bxb7 Bxd4 23.Ba6 Rb8 24.a4 Rb2 25.Ra3 d5 26.Bd3 Rd2 27.Bb5+ Nxb5 28.axb5 Bb6 29.Rea1 Rb2 30.Rxa7+ Bxa7 31.Rxa7+ Ke8, 1/2-1/2, V. Bhat (2398) – J. Donaldson (2399) [B27], San Francisco 2000] 9.dxe7 Qxe7+ 10.Qe2 Re8 11.Nc3 Qd6 12.Be3 a6 13.Bc4 b5 14.Bb3 Bb7 15.0-0 b4 16.Nb1 a5 17.Nbd2 a4 18.Bc4 Nb6 19.Bb5 Re7 20.Rfc1 Ng4 21.Qd3 a3 22.Rab1 axb2 23.Rxb2 Ra3 24.Rb3 Rxa2 25.Bg5 Bf6 26.Bxf6 Qxf6 27.h3 Nxf2 28.Qb1 Nxh3+ 29.gxh3 Rxd2, 0-1, Y. Nikitin (2355) – S. Solovjov (2497) [B27], St. Petersburg 2005) 6…Bg4 7.Bb5+ (7.Nc3 Nc6 8.Be3 e6 9.h3 Bxf3 10.Qxf3 f6 11.Bb5 fxe5 12.dxe5 Nge7 13.0-0-0 a6 14.Bxc6+ Nxc6 15.Qg4 Qe7 16.f4 Qf7 17.Ne2 h5 18.Qf3 0-0-0 19.Kb1 Kb8 20.Nd4 Nxd4 21.Bxd4 Rc8 22.Rc1 g5 23.fxg5 Qg6+ 24.Ka1 Qxg5 25.Be3 Qg6 26.Qf4 Rxc1+ 27.Rxc1 Bh6 28.Qd4 Bxe3 29.Qxe3 Rc8 30.Rxc8+ Kxc8 31.Qc5+ Kb8 32.Qf8+ Ka7, 1/2-1/2, A. Shirov (2732) – E. Perelshteyn (2534), Canadian Open 2009) 7…Nd7 8.Nbd2 a6 9.Bd3 e6 10.h3 Bxf3 11.Nxf3 Ne7 12.0-0 Qb6 13.Rb1 Nc6 14.Be2 0-0 15.b4 f6 16.exf6 Nxf6 17.Be3 Ne4 18.Qb3 Nxd4 19.Nxd4 Bxd4 20.Bxd4 Qxd4 21.Rbd1 Qb6 22.Bf3 Ng5 23.Bg4 Rf4 24.g3 Rxb4 25.Qc3 Rf8 26.Kg2 h5 27.Be2 Rxf2+ 28.Kh1 Ne4 29.Qc8+ Kh7 30.Qb8 Rb2 31.Rc1 Rxf1+ 32.Rxf1 Nf2+ 33.Rxf2 Qxf2 34.Qc7+ Kg8 35.Qc8+ Kg7, 0-1, K. Markidis (2342) – B. Macieja (2639) [B27], 38th Greek Team Ch. 2010.

1.e4 c5 2.Nf3 g6 3.c4 Bg7 4.d4 and now 4…cxd4 enters normal Maroczy Bind lines, while 4…d6, 4…Qa5+, and 4…Qb6 lead to sharper variations. Here’s a sample: 4…Qb6 5.dxc5 Qxc5 6.Be2 Nc6 7.0-0 d6 8.h3 Be6 9.Na3 Rc8 10.Rb1 a6 11.Be3 Qa5 12.Nd4 Nxd4 13.Bxd4 Nf6 14.Qe1 Qxe1 15.Rfxe1 0-0 16.Bf1 g5 17.b3 Nd7 18.Bxg7 Kxg7 19.Rb2 h5 20.Nc2 Ne5 21.Nd4 Bd7 22.Rd2 h4 23.f4 gxf4 24.Rf2 Ng6 25.Nf5+ Kf6 26.Be2 Kg5 27.Bg4 Rcd8 28.Rd2 Be6 29.Red1 Rc8 30.Nd4 Bxg4 31.hxg4 Kxg4 32.Nf3 f6 33.Rd5 Ne5 34.Kf2 Rh8 35.a4 b6 36.a5 bxa5 37.Rxa5 Rb8 38.Nd4 h3 39.gxh3+ Rxh3 40.Rg1+ Rg3 41.Raa1 Rh8 42.Rxg3+ fxg3+ 43.Kg1 Rh2, 0-1, S. Yeke (2321) – A. Mirzoev (2555) [A40], Turkish Team Ch. 2010.

Finally, there are still a lot of sharp unknowns after 1.e4 c5 2.Nf3 g6 3.d4 cxd4 4.Qxd4 Nf6 5.e5 (5.Bb5 a6 6.e5 axb5 7.exf6 Nc6 8.Qd3 b4 9.fxe7 Qxe7+ 10.Be3 Bg7 11.c3 0-0 12.0-0 d5!? (12…d6) 13.Bd4 [13.Qxd5 Be6 with tremendous compensation] 13…Bf5 14.Qd1 Nxd4 15.Nxd4 Be4 16.Nd2 Rfc8 17.Nxe4 dxe4 and Black had a clear advantage and went on to win, J. Gombac (2324) – D. Gjuran (2351) [B27], Slovenian Ch. 2010; 5.Nc3 Nc6 6.Qa4 d6 7.e5 dxe5 8.Nxe5 Bd7 9.Nxd7 Qxd7 10.Bb5 Bg7 11.0-0 0-0 12.Bxc6 Qxc6 13.Qxc6 bxc6 14.Be3 Nd5 15.Nxd5 cxd5 16.c3 a5 and Black had an excellent position in G. Jones (2556) – D. Gurevich (2488) [B27], Dos Hermanas 2010) 5…Nc6 6.Qa4 Nd5 7.Qe4 Nb6 (7…Ndb4 is extremely complicated, but White’s been doing rather well lately. 7…Nc7 is also common, but once again, White has scored well. Perelshteyn has championed 7…Nb6 for a few years, and after some ups and downs it looks like he might be onto something!) 8.Bf4 d5 9.exd6 Bf5 10.Qe2 Nd5 11.Be5 f6 12.Bg3 Ndb4 13.Na3 Qa5 14.Qd2 Bh6 15.Qxh6 Nxc2+ 16.Kd1 Nxa1 17.Qc1 Qa4+ 18.Kd2 e5 19.Bb5 Qb4+ 20.Qc3 0-0-0 21.Qxb4 Nxb4 22.Rxa1 Rxd6+ 23.Ke1 Rhd8 24.Be2 Rc6 25.Rd1 Rxd1+ 26.Kxd1 Nxa2 27.Ne1 Rd6+, 0-1, K. Kiewra (2311) – E. Perelshteyn (2534) [B27], Chicago 2010.

2...g6 3.Nf3

V.C. said: “A year before I played the same opponent, 3.Bc4 Bg7 4.Qf3 e6 5.Nh3 Nc6 6.Nb5 d6 7.Qf4 Be5 8.Qe3 a6 9.Nc3 Nf6 and I went on to win in 16 moves! I’ve considered ditching my Sicilian to play 1…g6 right away, rather than 1...c5 followed by 2...g6.  However I remembered our last game and realized I had nothing to fear from his opening against the Sicilian.” 

3...Bg7 4.Bc4

4.d4 cxd4 takes us back to the Accelerated Dragon.

4…Nc6 

The most logical move. Black clamps down on the d4-square and makes an eventual d2-d4 push problematic.

5.d3

5.0-0 is more flexible. I’ll explain why in the note to black’s 5th move.

5…Nf6 

Perfectly playable, but Black can aspire for more. For example 5…e6! followed by 6…Nge7 is an excellent way to handle the position since this deprives white’s pieces of the use of d5 and sets up an eventual …d7-d5 push for Black. The reason 5.0-0 is more flexible is that after 5…e6 White often gives 6.d4 a try when 6…cxd4 7.Nb5 (taking advantage of the hole on d6) has given reasonable results. However, now 5.d3 e6 6.d4 leaves White a full tempo down on those lines.

6.0-0

White gets a dull position after this. Instead, 6.e5 leads to a sharper battle: 6…Ng4 7.Bxf7+ Kxg7 8.Ng5+ Kg8 9.Qxg4 Nxe5 10.Qg3 d6 11.h4 when things start to heat up! For those that prefer …Nf6 to …e6 and …Nge7, 5…d6 followed by 6…Nf6 would avoid these complications.

6…0-0 7.h3 d6 8.Re1

White’s play has been toothless, but this position has still appeared 38 times in my database! However, all but one of the games is between low rated players.

 

 

 

 

 

 

 

 

 

 

 

 

 

 





8…Na5 

V.C. said: “White has played a few passive moves so I decided to irritate his bishop.

8…a6 9.a4 e6 10.Bg5 h6 11.Bh4 Qc7 12.Bg3 Nd7 13.Qd2 Kh7 14.Rab1 Rb8 15.Ne2 b5 16.axb5 axb5 17.Bb3 e5 18.Nc3 Ne7 19.Nd5 Nxd5 20.Bxd5 Nb6 21.Bb3 c4 22.Ba2 Ra8 23.Ra1 Be6 24.dxc4 bxc4 (Black’s clearly better) 25.Red1? c3 and Black won a piece and the game, J. Pelikian (2405) – Y. Yakovich (2560) [B50], Paris 2005.

9.b3??

V.C. said: “This blunders a pawn at least.

Someone with a little tactical experience would instantly notice the horrific possibilities along the open a1-h8 diagonal! 9.Bb3 is best, with a more or less equal game.

9…Nxc4?

Inaccurate. Stronger is 9…Nxe4! 10.Rxe4 Bxc3 11.Bg5 d5! 12.Bxe7 Qd7 13.Bxf8 (Better is 13.Bxd5 Qxd5 14.Bxf8 Kxf8 when Black has a winning game, but White can still put up a fight) 13…dxe4 and white’s dead.

10.bxc4

Also possible was 10.dxc4 Nxe4 11.Rxe4 Bxc3 12.Rb1 when white’s “just” a pawn down. Black’s much better, of course, but White has a solid structure and can swap dark-squared Bishops (leaving the dark-squares around black’s King a bit loose), stick his Rooks on the d- and e-files, and create a bit of pressure.

10…Nxe4 11.dxe4??

Ruining his pawn structure, blocking off the e-file, and losing the Exchange. That’s a lot of bad from one move! Correct was 11.Rxe4 Bxc3 12.Rb1 with a pawn less, but the battle is still ahead.

11…Bxc3 12.Bh6


 

 

 

 

 

 

 

 

 

 

 

 

 





12…Bg7??

V.C. said: “Perhaps 12...Re8 followed by taking one of the rooks would have been braver, but I was happy with a pawn advantage and white’s messed up pawn structure.

Tsk! Chess is a game of greed, and if someone gives you some free material, you have to take it on principle. Of course, if you think that it’s not “free” and that he’s getting something serious for it, then decline. But is that the case here? Let’s look: 12…Bxe1 13.Bxf8 Bc3 14.Bh6 Bxa1 15.Qxa1 f6 and White, who is down an Exchange and a pawn and has no compensation whatsoever for it, can quietly resign. The same can be said for 12…Re8 13.Qd3 Bxa1. Finally, if you are really seeing dark-square doom along the a1-h8 diagonal (perhaps you didn’t notice …f7-f6, closing it down), then 12…Bxe1 13.Bxf8 Bxf2+ 14.Kxf2 Qxf8 leaves Black with two extra pawns.

13.Bxg7 Kxg7 14.e5

I think this helps Black. Instead, White should be patient and just build in the center and on the kingside by Qd3 followed by Rad1.

14…Be6

V.C. said: “I’d rather improve my minor piece than his.

Since black’s a pawn up and also enjoys the superior pawn formation, it’s a good idea to exchange Queens if possible (black’s only worry are the dark-squares around his King – if the Queens go, the worries will also go). Thus: 14…dxe5 15.Rxe5 (Avoiding the trade by 15.Qe2 just makes matters worse after 15…f6) 15…Qxd1+ 16.Rxd1 Be6 17.Rxc5 Rfc8 18.Rb5 b6 when c4 will fall.

15.Qd3 h6?

V.C. said: “A waiting move that also restricts his knight.

You can’t wait around since White threatens to put pressure on you with Rad1. Also, 15…h6 weakens your kingside (this is actually a subtle hint for the puzzle that follows). Instead, 15…d5 takes matters into your own hands: 16.Ng5 (16.Rad1 dxc4) 16…Bf5 17.Qxd5 e6! (threatening the Queen and …Qxg5) 18.Qxd8 Rfxd8 when threats like 19…Bxc2, 19…Rd2, and 19…Rd4 ensure that Black will once again have a material advantage.

16.Qc3??

A silly one-move threat that allows Black to safely push his d-pawn. Instead, 16.Rad1 calmly increases the central pressure. Then 16…Re8 17.Qc3 Kh7 18.Re4 intends 19.Rh4 and, at the very least, will scare you to death (actually, white’s suddenly getting some serious play).

Instead of 16.Rad1 Re8, what happens after 16…dxe5 17.Qc3 Qc7?

 

 

 

 

 

 

 

 

 

 

 

 

 

 






16…d5

V.C. said: “I think the best way to stop the threat of the discovered check.

17.cxd5 Qxd5 18.a3

White needs to seek some activity or he’s toast. 18.Rad1 was best, when 18…Qxa2? 19.Qxc5 would considerably improve white’s chances. Instead, 18…Qc6 is right when black’s clearly better, but at least black’s Queen isn’t running rampant as in the game.

18…Qc4 19.Qb2 b6 20.Rad1 Rad8 21.c3 Qb3

V.C. said: “A lazy move.  I saw Qc1, but I didn’t really have a follow up.

Not having a follow up isn’t wise, but the move itself isn’t that bad. 

22.Qc1 Rd5 23.Nd2?

Poor. Instead 23.Rxd5 Qxd5 24.Rd1 had to be tried. Note that 23.Rxd5 Bxd5 24.Nh2 sort of threatens 25.Ng4, hitting h6 (it’s not that huge a threat, but at least White’s trying to fight back). After 24.Nh2 Be6 25.Rd1 white’s stopped Black from taking over the d-file. Of course, Black would still have a winning game, but it would take some technique to rake in the point.

23…Qa4

V.C. said: “I don’t think white should have given me the d-file and 23...Qa2 would perhaps have been more active.

There’s nothing wrong with either move.

24.Re4 Qa6?

You retain a huge plus after this, but much stronger was 24…Qd7!, laying claim to the d-file and creating a horrific pin against the poor Knight. After 25.Re2 Rad8 White has zero counterplay and will grovel until you put him out of his misery.

25.Rde1 Rfd8 26.Nf3 Rd3 27.Rh4 h5 28.c4?? 

V.C. said: “I don’t like c4, it stops …Bb3 but allows blacks queen into the action.

An awful move. It not only hangs a3, but it also places the c-pawn on a square where it will forever be eyed by black’s Bishop. After 27…h5, quiet moves won’t help White because he’s down material, has an inferior pawn structure, and is facing death by d-file. Since his only chance is going after the enemy King, 28.Qg5 (threatening both 29.Rxh5 and 29.Qxe7) suggests itself: 28…f6 29.Qg3 (still threatening 30.Rxh5) 29...Rd1 (getting rid of one of white’s attacking pieces, which would have leapt into action after exf6+) 30.Rhe4! (30.Rxh5 Rxe1+ 31.Nxe1 Rd1 32.exf6+ exf6 33.Qc7+ Bd7 leads to a quick loss for White) 30…Qc8 (Probably best. 30…Bf7 is also logical, though White gets a bit of play after 31.Kh2 Rxe1 32.Rxe1 Rd3 33.exf6+ exf6 34.Re7. Bad is 30…f5?? due to 31.Nh4! Bf7 32.Nxf5+ and the only one who is better here is White!) 31.Kh2 Rxe1 32.Nxe1 Bf7 and though Black has defended solidly and retains his large advantage, White can chip away on the kingside and/or down the e-file and hope to get lucky.

28…Qxa3 29.Qg5 f6 30.exf6+ exf6 31.Qg3 Rd1 32.Qc7+

V.C. said: “32.Rxh5 Rxe1+ 33.Nxe1 Qxg3 34.fxg3 gxh5 would have been a nice finish. I hadn’t considered Qc7+ so I took a minute considering king moves before the obvious hit me.

32…R8d7 33.Qc6


 

 

 

 

 

 

 

 

 

 

 

 

 






33…R1d6

V.C. said: “The queen can’t be allowed to stay on c6.

Why can’t the Queen be allowed to stay on c6? Your 33…R1d6 is a good move, but so was 33…Bf7 or 33…Bf5, allowing white’s Queen to “enjoy” c6 for a little while longer. You have to be very careful when using the word “can’t” during a game, since that pretty much becomes a self fulfilling prophecy in that any move you look at will be designed to chase the Queen off of c6 (if something far better existed, you wouldn’t notice it because of the uttered “can’t”).

34.Qe4 Bf5??

Throwing the win away. Instead, 34…Bf7 kept things tight and safe. This just goes to show that winning a won game is a nightmare for amateurs and pros alike!

 

 

 

 

 

 

 

 

 

 

 

 

 

 






35.Qe8 Rd1

V.C. said: “Stopping Re7+, which would have been painful.

No better is 35…Rf7 36.Re7, =.

36.Kh2??

Unaware that he was gifted with a miracle, White goes along with the program and continues to walk the road of defeat. Instead, 36.Rxd1 Rxd1+ 37.Kh2 Rd7 only leads to a draw. How can White save himself?

 

 

 

 

 

 

 

 

 

 

 

 

 

 






36…Rxe1 37.Qxe1 Qd3

V.C. said: “37.Nxe1 gives his 3 remaining pieces an amusing look, but I feel the threat of g4 more than makes up for it after say, 37...Rf7 then 38.g4 is awkward because 38...hxg4 leads to 39.Qh8 mate.  37…Qd3 also highlights a square that Nxe1 would have taken away.

37.Nxe1 was probably a better try, but white’s position is still hopeless after 37…Qc1! when 38.g4 is met by 38…Qf4+ 39.Kg1 Qe4! 40.Qxe4 Bxe4 41.gxh5 Rd4 and it’s all over. Your 37.Nxe1 Rf7 isn’t necessary, but it still wins after 38.g4 Bd7.

38.Qa1 Qd6+ 39.g3

V.C. said: “Weakening his kingside, but I doubt he wanted to see 39.Kh1 Qd1+.

39…Qd3

Even better is 39…Qd1, forcing the exchange of Queens since 40.Qa3 runs into tons of killer stuff. Of all black’s “killer stuff,” what’s best?

 

 

 

 

 

 

 

 

 

 

 

 

 

 




40.Rf4 Qe2

Even stronger is 40…Qb1! 41.Qa3? (41.Qxb1 is forced, but the endgame is hopeless) 41…Qf1 (threatening both 42…Qxh3+ and 42…Qxf2+) 42.Ng1 (42.Qe3 Qxh3+ 43.Kg1 g5! forces the win of white’s Rook for black’s Bishop) 42…Rd1 43.Qxa7+ Kh6 and White will soon be mated.

It’s important to put your opponent out of his misery when you have the chance since, if you allow him to keep breathing, you might find that he rises up and bashes you over the head.

41.Ng5??

Far better was 41.Nh4! when black’s Bishop can’t move due to Qxf6+. After 41…Qe6 42.Nxf5+ gxf5 black’s still winning, but black’s open King and his pawn weaknesses on f5 and h5 will force him to play accurately.

41…Qe5

V.C. said: “A cute pin, but it allows me force off the queens.

An excellent move that ends white’s counterplay. In general, trading Queens is a great thing to do if your King’s a bit open (and it’s even better if all endgames are easily winning for you!).

42.Qxe5 fxe5 43.Rf3 Rd3! 44.Rxd3 Bxd3

V.C. said: “The rest is easy.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

45.Nf3 Kf6 46.Nd2 a5 47.Kg2 a4 48.Kf3 a3 49.Ke3 a2 50.Nb3 Bxc4 51.Na1 b5 52.Kd2 b4 53.Kc1 b3 54.Kb2 e4 55.Kc3 Bd5 56.Kb2 Kf5, 0-1.

~ Lessons From This Game ~

* Mindlessly getting your stuff out in the opening (as White did in this game) will usually give your opponent a very nice position. Like it or not, you need to create a basic opening repertoire or the initial phase of the game will offer you nothing but misery as either color.

* Winning a pawn early in the game is great, but that doesn’t mean the game is over. You need to add to your material gain with more material gains, or ever-increasing positional gains. Never stop building up your position!

* In general, trading Queens is a great thing to do if your King’s a bit open (and it’s even better if all endgames are easily winning for you!).

* You have to be very careful when using the word “can’t” during a game, since any move you look at will be influenced by it.

* Pros and amateurs alike often have serious trouble winning won games.

* It’s important to put your opponent out of his misery when you have the chance since, if you allow him to keep breathing, you might find that he rises up and bashes you over the head.

[Would you like to have IM Silman comment on a game of yours? If so, send the game in PGN format, along with any questions and comments, to askjeremy@chess.com]

More from IM Silman
The Downs And Ups Of GM Elmars Zemgalis (Silman's Last Article)

The Downs And Ups Of GM Elmars Zemgalis (Silman's Last Article)

How To Build Winning Chess Positions

How To Build Winning Chess Positions