I've been looking at this 12. a4 line a lot the last couple of days. It certainly looks hard to equalize, if it all possible.

What I find strange, is that this move has only been played a lot from around 2010 by stronger players.
While the logic of advancing a passed pawn to a4, putting a knight on b5 and then start squeezing is not that hard to find as a plan against the Benko?

Aveskulov wrote on chess.com that he will look into 12. a4, but that was already 4 weeks ago. 
http://www.chess.com/blog/LuckyTiger/feedbacks-on-my-book

Still searching I guess 

And I just ordered "Attack with Black".... 

And given as "in my opinion strongest" by Pinski.

And to answer the following question:

gwnn wrote on 08/24/12 at 09:37:56:


There is at least one advantage of having the knight on f3 rather than e2: on f3, the knight supports a future e5. On e2, on the other hand, it not only does not support e5, but it also blocks the e-file so that Re1 does not support e5 either. Basically, by playing Nge2, White is basically giving up any e5 plans for the close future. For the same reason, Black can omit Nbd7 more easily against Nge2 than against Nf3.

I should point out an analogy of the position with 12.a4 to the e3-system. Typical plans and concepts can be borrowed from there.

[pgn][Event "Politiken zt"]
[Site "Munkebo"]
[Date "1998.09.11"]
[Round "1.2"]
[White "Hansen, Curt"]
[Black "Djurhuus, Rune"]
[Result "0-1"]
[ECO "A57"]
[WhiteElo "2610"]
[BlackElo "2495"]
[PlyCount "110"]
[EventDate "1998.09.10"]
[EventCountry "DEN"]
[Source "ChessBase"]
[SourceDate "1998.11.30"]

1. d4 Nf6 2. c4 c5 3. d5 b5 4. Nf3 g6 5. cxb5 a6 6. e3 Bg7 7. Nc3 d6 8. a4 O-O
9. e4 Ne8 10. Ra3 axb5 11. Bxb5 Nc7 12. Be2 Nd7 13. O-O Ba6 14. h4 h6 15. Re1
Qc8 16. Bf4 Rb8 17. Qc1 Kh7 18. Bd1 Rb4 19. e5 dxe5 20. Nxe5 Nxe5 21. Bxe5 Bxe5
22. Rxe5 Rxh4 23. Rxe7 Qd8 24. Re4 Re8 25. Bf3 Bb7 26. Rxe8 Qxe8 27. Rb3 Qe5
28. g3 Rb4 29. Qd1 Rd4 30. Qe2 Qxe2 31. Nxe2 Rd1+ 32. Kg2 Bxd5 33. Bxd5 Nxd5
34. a5 Nb4 35. Kf3 h5 36. Nc3 Ra1 37. Ra3 Rxa3 38. bxa3 Na6 39. Ke4 g5 40. Kf5
Kh6 41. Ne2 Nb8 42. f3 Na6 43. Ke4 h4 44. gxh4 gxh4 45. Ng1 Kg5 46. Ke5 f6+ 47.
Ke4 Kg6 48. Kd5 Kf7 49. Kc4 Ke6 50. Kb5 Kd5 51. Kxa6 Kc6 52. a4 c4 53. Ne2 h3
54. Nd4+ Kc5 55. Ne6+ Kd6 0-1[/pgn]

I haven't analysed the Nge2 idea, but it seems plausible based on White's plan. Also, it doesn't give Black a chance to exchange a pair of knights on f3 to gain access to e5 with tempo. On the other hand, it gives White less influence in the centre. Maybe Black should aim for ...e6 to put pressure on White's centre?

Oh, I was mostly defending Bologan I very much doubt if this line refutes the Benko - in general openings this established just don't get refuted. 

The real question is likely how easy/fun a line it is for black to play in practice. It's certainly not trivial if someone as strong as Bologan can get in this much of mess so easily.

Computer evaluations liable to be pretty useless for this of course. A bunch more GM games might give an idea.

15 .. Kf8 in Carlsen - Bologan vaguely intriguing actually, especially in relation to where this can go wrong for black.



Isn't this rather unpleasant for black? I guess that it isn't totally clear how white is going to improve his position but it's certainly a lot better organised than usual. Obviously, even if this is serious, black can very likely avoid it but there are dangers out there.

And actually 18 Bxe7+ might well explain avoiding Kf8 in a practical game - allowing those sorts of self evidently rather dangerous complications isn't terribly practical.