A) 77... a2 78.f8=Q a1=Q 79.Qf4+ Kh3 80.Qh4 mate.

B) 77... h1=Q 78.Bxh1 (78.f8=Q Qxd5+) a2 79.f8=Q a1=Q 80.Qf4+ Kh3 81.Qh4 mate.

Perhaps 72... Kg4 can save the game:

A) 73.Be6 Kxf4 74.Kxh5 Ke5 75.Bc4 Kd4 76.Be6 f4 77.Kg4 Ke4 78.h5 f3 79.h6 f2 80.h7 (80.Bc4 a2 81.Bxa2 f1=Q winning) f1=Q 81.h8=Q Qg1+ 82.Kh4 Qh2+ 83.Bh3 Qf2+:

A.1) 84.Kg4 Qf4+ 85.Kh5 Qe5+ 86.Qxe5+ Kxe5 winning.

A.2) 84.Kg5 Qg3+ 85.Bg4 Qe5+ 86.Qxe5+ Kxe5 winning.

A.3) 84.Kh5 Qf3+ and Black draws at least.

B) 73.Bc4 Kxh4 74.Kxf5 Kg3

B.1) 75.Kg5 h4 76.f5 h3 77.f6 h2 78.f7 h1=Q 79.f8=Q Qc1+ and draw.

B.2) 75.Kg6 h4 76.f5 h3 77.f6 h2 78.f7 h1=Q 79.f8=Q Qc6+ and draw.

C) 73.Kf6(h6) Kxf4(h4) 74.Kg6 Kg4 looks bad for White.

Second, from the puzzle position, Black needs a maximum of seven moves to queen after capturing the h pawn (one king move and six pawn moves). White needs only six moves after capturing the f-pawn (one king move, four pawn moves and a bishop move). For example, 72. ... Kxh4 73. Kxf5 Kg3 74. Kg5 h4 75. f5 h3 76. f6 h2 77. f7 h1=Q 78. Bxh1 a2 79. f8=Q a1=Q and White has all the chances for winning. That analysis eliminated 72. ... Kxh4.

That left 72. ... Kg4. Any other move loses material and the game to Kxh5. At first, I feared that White could move his king in response to Kg4. But Kh6 or Kf6 just lost material (e.g. 72. ... Kg4 73. Kh6?? Kxh4 (73. Kf6?? Kxf4)). That meant White's bishop had to move after 72. ... Kg4.

72. ... Kg4 73. Bc4 (best since it attacks f1). Black still needs seven moves after capturing either pawn. But with White's bishop attacking f1, playing Kxf4 allows White to queen in six. But if Black plays Kxh4, White will also need seven moves to queen (one king, four pawn and two bishop moves including Bd5).

The point is that white's bishop is perfectly positioned to kill black's pawn promotion efforts at a2 (of course), and more subtly, at h1. Also, white's king is perfectly positioned to take either Pf5 or Ph5.

And when your opponents pieces are so perfect, you want to force him to move one of them to a less-perfect square by burning up a tempo. That's what 72...Kg4! accomplishes:

White is in a little zugzwang. He can't move his king (which would give up a pawn for nothing) nor can he take his bishop off the a2-g8 diagonal (which would allows ...h2 & ...h1=Q), so he must move the bishop to some square where it DOESN'T guard h1.

Portisch vs H Westerinen, 1963 (72…?)

Black to play and draw

Material: P for B. Neither K is in any immediate danger in this sparse endgame. Presently, Bd5 is completely restricted to the a2-g7 diagonal by the threat of Pa3-a2-a1=Q and wins. Black should try to get a passed K-side P, so with 2 passed Ps, he can deflect the White B with one to permit the second to queen. For brevity, the following omits infeasible variations permitting either of these wins.

Let us perform a thought experiment, removing Bd5 and Pa3 until further notice, to analyze the resulting K+P endgame. First, the candidate 72…Kg4 is now transparent: as usual in a K+P endgame, Black seizes the opposition to prevent the capture of his Ps. Second, Black has a choice: which P to capture? Because of symmetry, after White captures the complementary P, White queens his P just after Black.

Now, put Bd5 and Pa3 on the board. The B alone cannot mate. So, if Black can queen first as above, the resulting Q+B vs. Q is a draw: Black just keeps checking, ensuring that the B never interposes with check (e.g., by placing his K on a dark square).

Candidates (72…): Kg4

72…Kg4

If White moves Kg6, he does no more than draw because Bd5 alone cannot mate.

(1) 73.Kf6 Kxf4 then …Kxh4

(2) 73.Kh6 Kxh4 then …Kxf4

(3) 73.Be6 Kxf4 74.Kxh5

[74.Kf6 Kg4 then …Kxh4 and Black at least draws]

74…Ke5

If White lets Black capture Be6, the Black Pa3 queens first, winning.

75.Ba2, e.g.

[75.Bc4 Kd4 can not be better, because the Black K can protect Pf5 from e3]

75…f4 76.Kg4 Ke4 77.h5 f3 77.Kg3

[77.h6 f2 78.Bc4 f1=Q 79.Bxf1 a2 and Black wins]

<[According to the Nalimov tables at http://www.k4it.de/index.php?topic=... I went wrong with 77…Ke3, trying to win, which loses against

78.h6 f2 79.Kg2 Ke2 80.Bc4+

The correct play (easily found to ensure a draw) is

77…f2 78.Kxf2 Kf5]>

(4) 73.B moves along the a1-h8 diagonal but not to e6, e.g., 73.Bc4

Black can force a draw, because White must expend a tempo to stop h1=Q.

73…Kxh4 74.Kxf5 Kg3 75.K moves off the f-file

75…h4 76.f5 h3 77.f6 h2

(threatening h1=Q with at least the Q+B draw above)

First, notice that the white bishop controls two important squares: a2 and h1. Second, f and h pawns are exactly in the middle of the board. Black and White easily force a passed pawn (72... Kxh4 73.Kxf5 Kg3 - the only move to pass the black pawn - 74.Kg5). In a pawn race, both have 4 squares ahead to be crowned. The black pawn would crown first, but the white bishop denies it or takes it (Bxh1). In either case, the a-pawn goes to a2 and White crowns first (f8=Q and a1=Q). Draw seems inevitable, but a mate net is setup (Qf3+ and Qg2#, or Qf3# if the h-pawn still occupies h2). So, if White crowns first and Black crowns on a1, Black is lost.

So, Black must force White to move the bishop away from h1, losing one tempo. With 72... Kg4, White has got the opposition and forces Black to move the bishop. If not, a white pawn falls, Black keeps the opposition again (73.Kf6 Kxf4 or 73.Kh6 Kxh4), and White has no way to defend its last pawn.

Now, the bishop has to move over the a2-g7 diagonal to keep a2 under control. Any square of that diagonal allows Black to win one tempo. But 73.Bc4 introduces a trap. The bishop now controls f1 and the mate net is unset. Now, Black is able to take the h-pawn and draw is ensured.

Oh, yes, I forgot the trap. If the mate net is unset, Black could crown after White by taking the f-pawn. Wrong. Now, White crowns its h-pawn controlling the a1-h8 diagonal and avoiding Black to crown on a1.

The idea is that any move of White's Bishop or the King after 72...Kg4! worsens White's position. After the forced Bishop move 73. Bc4, White no longer guards both a2 and h1 and Black has the one extra tempo needed to secure the draw.

P.S.:

I don' t have any software (I' m at work) to check that out. Maybe someone could analyse and see if 73. Ba2 (?) is as bad as it appears...?

Peace !

15. Rfe1 (preparation for center open file) b5
16. axb3 Rxb3
17. Bd3 Qb8
18. Rab1 a5 (...e6? 19. exd6 Nxd6 20. Bxd6 Rxd6 21. Ne4 Rb6 22. Nxc5 great advantage for white) 19. Na4 a4
20. Bg5 f6?(or Qd8)
21. e6 Bc8 (...fxg6? 22. exd7 Nf6 23. Nxg5 Nxd7 23.Rxe7 almost winning for white)

22. Bf5 clear positional advantage for white and with kingside attack, I don't think it will reach 70+ moves for white to win (not to draw).>