From 38. Rd1 e5 39. g6 (line B1) exf4 40. g7 Ne7 41. h6 Kc4/c5 42. Rxd4(+) Kxd4 43. g8=Q! Nxg8 44. h7 Ne7 45. h8=Q+ Kc4, how would you win as White?
The FAQ gave "+/-" after just one more move,
B11) 46. Kg2, but 46...Nc6! appears sufficient to draw!:
B111) 47. Kf3? Nd4+ 48. Ke4 d5+! 49. Kxf4 b2, as again even without a d-pawn this is drawn.
B112) 47. Kf2/f1?! Ne5! (47...Nd4 48. Qc8+ Kd3 49. Qxb7 Kc3 50. Qc7+ Kd3 51. Qxd6! does win, as Black falls apart after 51...b2 52. Qb4!) 48. Qc8+ Kd4/b4 49. Qxb7(+) Kc3!, and suddenly Black is forming an unassailable chrysalis with ...Nc4. I do not see a way for White to win, and neither does MacChess...
B113) 47. Qc8? b2 48. Qxb7 Nb4 49. Qe4+ Kb3/c3 is once again drawn without Black's other pawns.
B114) 47. Qa1 Ne5!, and now:
B1141) 48. Qa4+?! Kc3 49. Qa5+ Kc2 50. Qc7+ Kd2 51. Qxd6+ (51. Qxb7 Kc3! is a worse version of B12) Nd3 is a laborious win without Black's other pawns, but probably not a win with them&emdash;for instance, on 52. Qd5 b2, 53. Qxb7 only draws as 53. Qb3 is needed without Black's pawns.
B1142) 48. Qc1+ Kd3! 49.
Instead, White must disrupt Black's coordination immediately, with a little old-time materialism:
B12) 46. Qg7! and now:
B121) 46...Nc6 47. Qxb7 with:
B1211) 47...Ne5 48. Qc7+! (not 48. Qe4+? Kc3 49. Qxf4 b2, when as the analogous position without Black's d-pawn lists 50. Qxe5+ as the only winning move, this is probably drawn), and the capture on d6 will be fatal.
B1212) 47...Nd4 48. Qc7+! (too materialistic is MacChess' 48. Qf7+? Kd3 49. Qxf4? (49. Qc7+, last call...) b2, which fails even without Black's d-pawn) and now:
B12121) 48...Kd3 49. Qxd6 Kc4! (49...b2 50. Qb4+/-). Now 50. Qxf4? b2 is a bonafide draw, even if White's King were on f2. But 50. Qc7+! Kd3 51. Qb6! catches Black in an inescapable bind: 51...b2 52. Qb4! wins the pawn, while 51...Kc3 52. Qc5+ Kd3 53. Qb4 sinks deeper into quicksand, so 51...Kc4 52. Kg2. Now 52...f3+ 53. Kf2 Kd3 54. Qb4 is a fatal Zugzwang, 52...Nb5 53. Qe6+ Kb4 54. Qe5! keeps all under watch, and 52...Nc2 53. Qc5+ Kd3 54. Qf5+ Kc3 55. Qe5+! keeps watch over b2, so Black appears lost. Also, 51...f3 52. Kg1 Ne2+ 53. Kf2 Kc2 54. Kxf3 EGTB+/- #21 is an important win for White, though there is also 52. Qb4 here.
B12122) 48...Kd5 49. Qc3! leaves Black cut off.
B1213) 47...Nb4 48. Qc7+! wins quickly (as does 47...Na5 48. Qb6!).
B122) 46...Nd5! 47. Qxb7 and now:
B1221) 47...Ne3 48. Qc7+ Kd3 49. Qxd6+ Kc3, and now we reach one of the most horrific EGTB surprises for White:
Position after 48...Kc3 in subline. Accuracy is demanded, even a Queen up!
50. Qxf4 Nc4! is drawn! This is so even if White's King were on g2! However, 50. Qe5+! Kc2 51. Qxf4! is a win in 25, even though Black can reply 51...b2, go figure! On 50...Kd3, White must again avoid 51. Qxb4? Nc4=, and play the nice blockading 52. Qb2! Kc4 53. Qd2! Now 53...Nc2 54. Qxf4+ is EGTB+/- #26, and 53...Nd5 54. Kg2 (zugzwang) Nc3 55. Qxf4+ is #21, while here 54...Nb4 55. Qxf4+ is #21 as well. Also vital here is that 50...Kb4 51. Qxf4! is mate in 24.
B1222) 47...Nc3! and now White is in for bigger shocks: if 48. Qc6+? Kd3, the position without Black's f and d-pawns is such that 49. Qxd6+ would only draw! Indeed, White's only winning move in that position is given as 49. Qg2, and that seems unlikely to work when the pawns on d6 and f4 exist. White has to put materialistic computers away and try 48. Kg2, and now:
Position after 48. Kg2 in subline. Two Pawns on the 6th are not better than one.
B12221) 48...d5 49. Kf3 and now:
B122211) 49...d4 50. Kxf4 d3 sets up 51. Ke3? b2!=. White also comes up empty on 51. Qa6+ Kb4! 52. Qxd3 b2! EGTB=. The only try here seems to be 51. Qa6+ Kb4 52. Qb6+, when 52...Kc4 53. Ke5! Ne2 54. Qc6+ Kb4 55. Kd5! b2 56. Qc4+ Ka3 57. Qxd3+ Kb4 58. Qc4+ is a pretty win in 23.
B122212) 49...Nd1 50. Qc6+ Kb4 51. Qxd5 Ne3 52. Kxf4 is EGTB+/- #21.
B122213) 49...Ne4 is MacChess' choice, and sets the trap 50. Kxf4? Nc5 51. Qb8 b2!=. However, 50. Qa6+! and now:
B1222131) 50...Kc3 51. Qc6+ forces 51...Kd4, when 52. Kxf4 is fine because 52...b2 53. Qc2 ties Black up. Black can thrash with 52...Nc5, but 53. Qf6+ Kc4 54. Ke3 wins, or 53...Kd3 54. Qe5!
B1222132) 50...Kb4. Black is hoping to get ...Nd2+ and ...Nc4 in. The limited usefulness of MacChess here is shown by its going in for 51. Qa1 Nd6 52. Qd4+?! Nc4 53. Qxd5? "+438", which is drawn without Black's f-pawn by 53...b2; also unclear here is 52. Kxf4!? Nc4 as White's King is cut off. However, White appears to thread through to a win with 51. Kxf4! b2 52. Qc6+ Kb4! 53. Qc2! (not 53. Qxd5? Nc3! EGTB=) Ka3 54. Ke3 Nd6 (54...Nf6 55. Qc3+ Ka2 56. Qa5+ Kb3 57. Qb5+ Kc3 58. Qd3+ Kb4 59. Kd2+/- ) 55. Kd2! Nc4 (55...Nb5 56. Qc5+ +/-) 56. Kc3 Ka2 57. Kb4 Ka1 58. Qa4+ Kb1 59. Kc3 Ne3 60. Qd4+/-. Also losing here is 51...Nd2 52. Ke3! Nc4+ 53. Kd4 b2 54. Qa2+/-.
B12222) 48...Na2!? 49. Qc6+ Kd3 50. Qxd6+ is a conundrum: the analogous position without Black's f-pawn is a win, but does the f-pawn help here? MacChess gives 50...Kc2 51. Qg6+ Kc1 52. Qc6+, and this does appear to win as Black's Knight is dim.
B12223) 48...Nb5!? is Black's last chance. White is now able to remove the f-pawn with check and without giving Black any extra chances: 49. Qc6+ Kb4 50. Qe4+ Kc3 (50...Ka3 Qc4!+/- is Black's main unfortunate problem) 51. Qf3+ Kc4 52. Qf1+! (avoiding 52. Qxf4+?! Nd4 53. Qxd6? b2! EGTB=) Kb4 53. Qxb4+ Kc3. Now, besides bringing in his King, White can win by establishing the bind of B12121): 54. Qa4(!) Nd4 55. Qa5+! and:
B122231) 55...Kd3 56. Qb4! d5 57. Kf2 (zugzwang) Ke4 58. Ke1+/-.
B122232) 55...Kb2 56. Qd2+ Nc2 57. Qxd6 EGTB+/- #23. (Note that with WQ on d5 rather than d6 this would be drawn.)
B122233) 55...Kc4 56. Qc7+ Kd3 (56...Kd5 57. Qc3 is hopeless) 57. Qxd6+/- (#23, in fact).
B122234) 55...Kc2 56. Qc7+, and wherever Black's King goes, 57. Qxd6 is +/-.
Thus this entire variation does seem&emdash;surprisingly narrowly!&emdash;to be a win for White. The one general theme worth retaining from this (besides having an EGTB server in your head:-) is exemplified by B12121) and the last group of lines: A Knight is often better on the file next to a pawn it is escorting than two files away.