Antonio Torrecillas wrote:
Some days ago I proposed this game to study:

[Event "Match des Legendes"]
[Site "Porto Vecchio FRA"]
[White "Spassky, B."]
[Black "Karpov, Ana"]
[Result "1-0"]

1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Nd7 5. Nf3 Ngf6 6. Nxf6+ Nxf6 7.h3
Bf5 8. Bd3 Bxd3 9. Qxd3 e6 10. O-O Be7 11. c4 O-O 12. b3 c5 13. Bb2 cxd4
14. Rfd1 Qa5 15. Bxd4 Rfd8 16. Qe2 Qf5 17. Rd3 Qe4 18. Qxe4 Nxe4 19.Rad1
Kf8 20. Kf1 f6 21. Be3 Rxd3 22. Rxd3 Ke8 23. Nd2 Nxd2+ 24. Rxd2 a6
25.Ke2 Rd8 26. Rxd8+ Kxd8 27. c5 Kd7 28. Kd3 Bd8 29. b4 Bc7 30. Kc4 h5
31. a4 Be5 32. b5 axb5+ 33. axb5 Kc7 34. g4 hxg4 35. hxg4 Kd7 36. f4 Bb2
37. f5 e5 38. Kd5 Ba3 39. g5 fxg5 40.Bxg5 Bb2 41. Bh4 Bc3 42. Bg3 1-0

I wrote about the engine suggestion 28....Kc6!! and I showed some
tactical details about it in previous messages.

The second all engine suggestion was 35...g5. I think that proposition
to be a mistake. Maybe engines can not see too far in that ending.
I would like to add some analysis about it. Let's see!

FEN:
8/1pk5/4pp2/1PP1b1p1/2K3P1/4B3/5P2/8 w - g6 0 36

ASCII
wKc4,Be3,Pb5,c5,f2,g4
bKc7,Be5,Pb7,e6,f6,g5

White can obtain a pawn ending with 36.Bd4 Bxd4 37.Kxd4 Kd7
In that ending white has a passed pawn in the queen wing which can be
used as distraction to win the game in the kings wing. The problem is
that white king has no accesss to king wing.

White has two possible ideas:
- To open king wing with f4. The problem is that there are too many
simplifications. I think that possibility do not work.
- To force black to move his king wing pawns trying to play Ka5-b6
(which would be an easy win following c6, Kxc6-d6). That can be played
with and without playing f3. I think both options win.

a) 38.Kc4 Kd8 39.Kb4 Kc7 (39...Kd7 40.Ka5 Kc7 41.f3 wins) 40.Ka5 and
white wins in all lines:
- 40...f5 41.Kb4! followed by Kc4-e5 +-
- 40...b6 41.Ka6! +-
- 40...Kb8 41.Kb6 followed by c6 +-

b) 38.f3 Kc7 39.Kc4 Kd7 40.Kb4 Kc8 41.b6! f5 42.Kc4! f4 43.Kb5! +- but
this line can be unnecesaryly complicated.

I'm wrong?

Antonio T.

For the convenience of readers, I have created a ChessUp diagram using
your FEN. The position after your (alternate) move of 35) ... g5 :

http://tinyurl.com/ptdkq