Q3: After 1.d4 Nf6 2.Bf4 g6 3.e3 Bg7 4.Nf3 0-0 5.Be2 d6 6.0-0 Nfd7 7.h3 e5 8.Bh2 f5 9.c4 Nc6 10.Nc3 g5 11.dxe5 now you only cover Black responding with 11... Ndxe5, but what should White do against 11...dxe5? (Dia)
A: This recapture probably should have been mentioned in "Win with the London System" as it had been played by 2400 player Gonzalez Velez when the book was written (later it has also been employed by GM Nataf). However, at least to me, it appears less natural than 11...Ndxe5 which immediately frees Black's somewhat entangled queenside. Still the move clearly has some virtues as it keeps Black's kingside pawn front mobile. What's more problematic: it leads to extremely tense positions which are difficult to analyze and evaluate. I will give it a try with the assistance of some analysis engines (Mainly Rybka 2.3 and Fritz 11) but must warn the readers that this kind of positions are really GM territory.
I believe White should continue 12.Nd5!
Initially the computers seem to like 12.Qd5+ Kh8 13.Rad1, but after 13...h5 White’s queen is tactically exposed in some lines and it seems that Black has sufficient counter-play on the kingside:
a) 14.Qb5 g4 15.hxg4 hxg4 16.Ne1 a6! (16...Rf6 17.Bxe5!) 17.Qa4 Rf6 and Black’s attack seems dangerous.
b) 14.Rd2 a6 15.Rfd1 Qe7 16.e4?! g4 (16...Nc5 is simple and good) 17.Ne1 f4 18.Qd3 Nd4 19.Nd5 Qf7 (Black obviously is already better) 20.h4? Nc5 21.Qb1 g3 0–1 Zimny-Tirard, Koszalin 1999.16.Ne1 improves but Black clearly is in good shape.
12...a5 (Dia)This was the choice of the strongest player to take on Black’s side but the move is far from obvious and probably this is a critical junction:
a) 12...Nb6 13.Qb3 g4 14.hxg4 fxg4 15.Ne1 Na5 16.Qc3 Nxd5 17.Qxa5 Ne7 18.Rd1 looks good for White.b) 12...Nc5 13.b4 Ne6 14.b5 e4 15.bxc6 exf3 16.Bxf3 Bxa1 17.Nxc7 Qxd1 18.Rxd1 Nxc7 19.Bxc7 bxc6 20.Bxc6 gave White a safe extra pawn in Bosque Ortega-Gonzalez Velez, Barbera 1997.
c) For good or bad 12...f4!? seems to be the consistent course:c1) After 13.Nd2 Nf6 14.Bf3 Bf5 15.Nxf6+ Qxf6 16.Ne4 Qg6 17.Bh5 Qh6 18.Bf3 fxe3 19.fxe3 g4 a draw was agreed in Sprotte-Grabics, Balatonbereny 1997 even if Black was close to winning.
c2) I like 13.exf4 which opens the centre somewhat and makes kingside pawn storm more risky for Black, e.g.:c21) 13...gxf4 14.Qc2 Nc5 15.Rad1 Bf5 16.Qc1 e4 17.Nxf4 Qf6 18.Nd5 Qxb2 19.Qxb2 Bxb2 20.Nh4 is clearly better for White.
c22) 13...exf4 14.Qc2 Nc5 15.Rad1 Bf5 16.Qc1 +=.
13.Nxg5!?A very interesting idea which leads to positions that are hard to evaluate but 13.Qa4 could be an improvement:
a) 13...g4 14.hxg4 fxg4 15.Ne1 Nc5 16.Qb5 Ne4 17.Rd1 Nd6 18.Qb3 Rf7 19.c5 must be good for White.b) 13...Nc5 14.Qa3 Ne6 15.Rad1 Bd7 (15...Qe8? 16.Nxg5!) 16.Nd2 also seems to favour White.
c) 13...h5 14.Rfd1 g4 15.hxg4 hxg4 may be critical, e.g., 16.Ne1 Nc5 17.Qa3 Ne4 and now White has the tactical finesse 18.Nb6 Nd4 19.exd4 cxb6 20.Bxe5! (20.dxe5 Qh4 21.Qe3 Kf7! =+) 20...Bxe5 21.dxe5 Qh4 22.Qe3 Kg7 23.g3 Qh5 24.Ng2 and it seems Black’s kingside initiative has been neutralized.
13...Qxg5 14.Nxc7 Rb8 15.Ne6White collects two pawns and the exchange for his knight. In general that's a fair deal perhaps favouring White very slightly - with chances increasing as the endgame approaches. It's also very unbalanced and the correct evaluations may depend on rather fine positional points (but mainly on White's king's position).
15...Qe7 16.Nxf8 Qxf816...Nxf8 may improve Black’s co-ordination somewhat but the resulting position is still hard to evaluate.
17.Qd5+ Kh8 18.Rfd1 Bf618...Nc5 may be better and looks roughly balanced after e.g., 19.Qd6 Be6 20.Rac1 a4 21.Qxf8+ Rxf8 22.Rd6 Bf6 23.b3 axb3 24.axb3 Ra8 (24...Nxb3 25.Rb1 Nc5 26.Rb5 Be7 27.Rd5 +=) 25.Rb1 Ra2 26.Bf3 e4 27.b4 Nxb4 28.Rxb4 Ra1+ 29.Rd1 exf3 30.Rxa1 Bxa1 31.gxf3 =.
19.Bf3White doesn't achieve anything particular with 19.Qb5 Ra8 .
19...Nc5 20.Qd6 (Dia)
This position from Prie-Nataf, Paris 2006 is quite hard to evaluate. In my experience computers tend to evaluate this material imbalance as more favorable for White than most human masters. Whether this is due to poor evaluation functions or reflects the fact that there are tactical resources available for the rook and pawn side that humans tend to overlook is hard to tell. Rybka 2.3 says +0.85 at 18 ply. That seems too optimistic but it's also clear that White has a rather low losing risk after the exchange of queens. For what it's worth, the game ended in a draw after the further moves 20...Ne6 21.Bxc6 Qxd6 22.Rxd6 bxc6 23.Rxc6 Kg7 24.Rd1 Kf7 25.b3 f4 26.Kf1 Bb7 27.Rcd6 Be7 28.Rd7 Bc6 29.Ra7 a4 30.Rd6 axb3 31.axb3 Be8 32.Rd5 Kf6 33.exf4 exf4 34.Ra6 Rxb3 35.Bxf4 Bg6 36.Bg5+ Kf7 37.Ra7 Nxg5 38.Rxg5 Bd3+ 39.Kg1.