off-topic: I just removed Windows Vista and installed Fedora (Linux) on my laptop...my chess programs and data are unavailable to me for some time...then, don't be angry for no quick reply at your next posts (need time to install more stuff).

After reading last chesspub update, I recorded some lines and ideas, about Boleslavsky variation and Nakamura Qb6. The topic is about the alternative move 18...Ba3!? 

Reference game is Nakamura's game vs Anand in Tata Steel tournament January 2013. There are short youtube videos with Nakamura and Anand, explaining their point of view after the game (draw). I recall first moves to reach critical position (no bothering about move order in game):

1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.e5 Nfd7 5.f4 c5 6.Nf3 Nc6 (6...Qb6!? (Korchnoi) 7.Be3 Qxb2? 8.Nb5 Na6 9.a3 Be7 10.Rb1 Qb2 11.Qc1 +/-) 7.Be3 cxd4 (7...Qb6 8.Na4! Boleslavsky main plan) 8.Nxd4 (8.Bxd4 Nxd4 9.Nxd4 Qb6) Qb6!?  (Nakamura and others)

A) 9.a3 g5 (9...a6 10.Qd2!) 10.fxg5 (10.Be2 Bc5= ; 10.g3 Bc5 =+ ) Ndxe5 11.Be2 Bc5 12.Na4 Qa5+ 13.c3 Bd6 14.b4 +=

   or 9...Bc5 10.Na4 Qa5+ 11.b4 Qxa4 12.Bb5 Bxd4 13.Bxa4 Bxe3=

   or 9...Nxd4 10.Bxd4 Bc5 11.Na4 Qa5+ 12.c3 (12.Nc3=) Bxd4 13.Qxd4 b6! 14.Qb4 Qxb4 15.axb4 Ke7 

B) 9.Qd2 Qxb2 10.Rb1 Qa3 

  B1) 11.Ndb5 Qa5 12.Nxd5 Qxd2+ (12..exd5 13.Qxa5 Nxa5 14.Nc7+ Kd8 15.Nxa8 b6 16.13.Kxd2 exd5  14.Nc7+ Kd8 15.Nxa8 b6 16.Nxb6 axb6 17.Rxb6 +=) 13.Kxd2 exd5 14.Nc7+ Kd8 15.Nxa8 d4 or 15..b6 =+

  B2) 11.Bb5 Nxd4 12.Bxd4 a6 (12...Bb4 13.Rb3 Qa5 14.a3 Bxc3 (14...Bxa3? 15.Nxd5 ; 14...Be7 15.f5!? exf5 16.Nxd5 De Firmian and Nijboer-Porat,Cappelle 2006 (chessgames),Nijboer-Kuijk,Wijk aan Zee 1996 (Tiemann)  Vit-Ree,1985 (Pavlov, EE 1997))) 15.Bxc3 Qd8 16.Ba5! b6 17.Bb4)

13.Bxd7 Bxd7 14.Rb3 (14.Rxb7 Bb4) Qe7 (14...Qa5 15.Bb6) 15.Rxb7 

15....Qd8   (15...Qh4+ is the move in Anand-Nakamura)

16.Bb6 Qc8

(16..Qh4+?!  17.g3 Qh3 18.Rxd7! Kxd7 19.Nxd5 Rb8 20.Nf6+ Kc6 21.Qd7+ Kxb6 22.Nd5+ Kc5 23.Kf2 +-)

17.Rc7 Qd8 18.Qd4



and now the "vacating square for bishop" move

  18...Ba3!? (18...Rc8 19.Rc6 (19...Ra7 Qe7!?) Rxc6 20.Bxd8 Bc5 (20..Rc4 21.Qa7 Rxc3 (21..Kxd8 22.Ne2 Bc5 23.Qa8+ Bc8 24.Kd2 Re8 25.Rb1 Re7 26.c3 +/-) 21.Qa4! Kxd8 (21..Rc8 22.Qa5) 22.Ke2 Ke7 23.Rb1 (23.f5=)  23...Rhc8 (23...Rd8?! 24.f5 Ke8 25.Qg4 exf5 26.Qxg7 Bf8 27.Qg3 Be6 28.Kd1 Rdc8 29.Ne2 Rdc8 30.Nf4  with the idea Nxe6 removing king cover or 27...Rc5 28.Qf3 Be6 29.Kd1 Rdc8 30.Ne2 Rxc2 31.Nd4 +/-)  24.Rb7 R8c7 25.Rxc7 Rxc7 26.Qa5 Rc6 27.Kd3 Bf2 28.Ne2 Ke8 29.Kd2 with initiative for White)

  Now

A) 19.oo Rc8 20.Rb7 Qxb6 (10..Qe7!?) 21.Bxb6 Rxb6 22.Bc5 Ne2 23.Nxd4 Ke7 24.Rxa6 Ra8 25.Rxa8 Rxa8 26.Kf2 Rxa2=

B) 19.Rb7 Qh4+ 20.g3 Qe7 21.oo Rc8 22.f5 Qb4 =+

C) 19.f5 Rc8 20.Rc6 Qe7 21.Rxc8+ Bxc8 22.oo Qb4 23.Rb1 Qxd4 24.Bxd4 Be7=

D) 19.Nb1 Be7! 20.c4 (20.Ra7 Qc8= because (20..Qb8 21.Rxd7)) Rc8 21.Rb7 Bb4+ (21..Rxc4 22.Qxc4)  22.Kf2 (22.Ke2 Qh4) Qxb6 23.Rxb6 Bc5 24.Qxc5 Rxc5 25.Rb8+ Bc8 26.Nd2 oo 27.Rc1 Bd7 28.Rxf8 Kxf8 29.Ke3 Bc6 30.Kd4 Ra5 31.Rc2=

E) 19.Ra7 Qc8 =