25 July 2009

What's the Logic?

Combining the games I collected for my post on CCM PGN Game Scores together with the CCM games I received from Chess Tiger, which chess960 players have been the most active at Chess Classic Mainz (CCM)? The top five active players are listed in the following table along with the number of games I have on file (there might be some games missing):-

66 Aronian
56 Svidler
53 Bacrot
45 Almasi
34 Naiditsch

GM Levon Aronian's latest CCM appearance was in 2007, where he won the overall title (see Chess960 World Championships for details). Here's the start position of his game against GM Rustam Kasimdzhanov from round two of the preliminary section in that event.

Start Position 383

And here's the PGN, as provided by CCM.

[Event "FiNet Chess960 Rapid World Championship"]
[Site "Chess Classic Mainz"]
[Date "2007/8/14"]
[Round "2"]
[White "Aronian"]
[Black "Kasimdzhanov"]
[Result "1-0"]
[Variant "chess 960"]
[SetUp "1"]
[FEN "nrkrnqbb/pppppppp/8/8/8/8/PPPPPPPP/NRKRNQBB w DBdb - 0 1"]

1.f4 Nb6 2.f5 f6 3.Nb3 e5 4.fxe6 dxe6 5.g3 Nd6 6.Nd3 Qe7 7.Ndc5 Bf7 8. Na5 O-O 9.Ncxb7 Be8 10.Nc5 f5 11.Qf3 Nbc4 12.Nc6 Bxc6 13.Qxc6 g6 14.c3 Ne5 15.Qa4 c6 16.Nd3 Rb7 17.Bc5 Rc8 18.Nxe5 Bxe5 19.d4 Bg7 20.O-O Qd7 21. Bxd6 Qxd6 22.e4 fxe4 23.Bxe4 e5 24.Qc4+ Kh8 25.d5 c5 26.b4 Rbc7 27.b5 Rd8 28.a4 Qb6 29.Kg2 Rd6 30.a5 Qxa5 31.Ra1 1-0

White's first move 1.f4 is easy to understand. It opens lines for a couple of pieces, prepares Nf3, and attacks the Pawn on a7. Black's response 1...Nb6 is also straightforward. It blocks the attack on a7 by developing the Knight to its natural square. Then there's a mystery -- what to make of 2.f5?

In Differences Between Chess and Chess960, I wrote that regarding the Initial moves, in chess 'Moves are chosen according to repertoire, respecting chess logic as necessary', while in chess960, 'Moves are chosen according to chess logic'. What's the logic behind 2.f5?

Here's my answer: If White plays something straightforward like 2.Nb3, Black will answer 2...f5, maintaining the symmetry along with the balance (or equilibrium) in the position. With 2.f5, White prevents Black from getting this easy equality. The advanced Pawn on f5 is not in any danger, because: (1) It is protected against any immediate attack by the Queen on c1, and (2) Black must eventually play ...g6 (or ...g5) to develop the Bishop on h8, when the f-Pawn can be swapped off by f5xg6. • Does this make sense to you or do you have a better line of reasoning?

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