Lasker - Lipke; Stockfish has difficulty after 39. g4

[TommyTC]

Recently Chess.com had an article on games of Lasker. There is an interesting position that Stockfish has difficulty evaluating.

Lasker,E - Lipke,P 1-0, Hauptturnier Siegergruppe 1889

[d]8/1pp1k3/p2p1n1p/5K2/5PPP/8/1P1B4/8 b - - 0 39

After 39. g4 an interesting position is on the board where White is a pawn behind yet winning.

While analyzing 39. g4, Stockfish thinks 39...Kf7 40. g5 Nd5 41. h5 is winning. In my later analysis I found 39...Kf7 40. g5 Nd5 41. Ke4! is the winning move while 41. h5? only draws. Stockfish continues to think 41. h5 is the best move from depth 38 to depth 78.

It is interesting to see the wide swings in evaluation values over several hours of analyzing. Here are some of the key evaluations and partial PVs while analysing the position after 39. g4:

Analysis by Stockfish 10 64 BMI2:

39...Kf7 40.g5 Nd5 41.Ke4
+/- (1.37) Depth: 34/48 00:00:08 86859kN, tb=308455

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 hxg5 43.fxg5
+- (1.78) Depth: 38/58 00:00:34 375MN, tb=1755821

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 b5
+- (2.90 --) Depth: 43/60 00:04:05 2665MN, tb=12177331

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 c6
+- (1.79) Depth: 46/70 00:04:59 3227MN, tb=15139891

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 c6
+/- (1.12) Depth: 64/89 01:14:20 41228MN, tb=380884336

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 c6
+/- (1.12) Depth: 77/109 04:15:15 129577MN, tb=1668963575

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 c6
+/- (1.21 --) Depth: 78/104 07:33:40 228675MN, tb=2147483647

39...Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 c6 43.Bc3 d5+ 44.Ke5 hxg5 45.fxg5 c5 46.Bd2 d4 47.Ke4 Ke6 48.Bf4
+- (2.29 --) Depth: 78/104 11:55:16 365008MN, tb=2147483647


In the last PV, 47...b5 is 0.00.

[carldaman]

If SF really thought it was winning you'd see much higher scores. The oscillation in score suggests it's not really sure - it might be winning, but then again it might not.

[zullil]

Recently Chess.com had an article on games of Lasker. There is an interesting position that Stockfish has difficulty evaluating.

Lasker,E - Lipke,P 1-0, Hauptturnier Siegergruppe 1889

[d]8/1pp1k3/p2p1n1p/5K2/5PPP/8/1P1B4/8 b - - 0 39

After 39. g4 an interesting position is on the board where White is a pawn behind yet winning.

Here's the game:
[pgn][Event "Hauptturnier Winners' Group"] [Site "Breslau GER"] [Date "1889.07.24"] [EventDate "?"] [Round "1"] [Result "1-0"] [White "Emanuel Lasker"] [Black "Paul Lipke"] [ECO "A07"] [WhiteElo "?"] [BlackElo "?"] [PlyCount "93"] 1.e4 e5 2.Nc3 Nf6 3.g3 Bc5 4.Bg2 O-O 5.Nge2 d6 6.O-O Nc6 7.d3 Be6 8.Nd5 Bxd5 9.exd5 Ne7 10.Bg5 Nd7 11.d4 exd4 12.Nxd4 h6 13.Be3 Ne5 14.Qe2 Qd7 15.h3 Rae8 16.Rae1 a6 17.f4 N5g6 18.Qf2 Bxd4 19.Bxd4 Nf5 20.Bc3 Rxe1 21.Rxe1 Re8 22.Bf3 Rxe1+ 23.Qxe1 Nfe7 24.Kg2 Qa4 25.Qd2 Qxa2 26.Qd4 f6 27.Qe4 Qb1 28.h4 Kf8 29.Bh5 f5 30.Qd4 Qxc2+ 31.Kh3 Qe4 32.Qxg7+ Ke8 33.Bxg6+ Kd7 34.Bxf5+ Qxf5+ 35.Qg4 Qxg4+ 36.Kxg4 Nxd5 37.Bd2 Nf6+ 38.Kf5 Ke7 39.g4 d5 40.g5 hxg5 41.fxg5 Nd7 42.g6 Kf8 43.h5 d4 44.h6 Kg8 45.h7+ Kh8 46.Ke6 Nf8+ 47.Kf7 1-0[/pgn]

[Dann Corbit]

The main problem with SF recognizing the problem is that d5 is a much worse response than Kf7. Yes, black is in big trouble.
But after 39.. d5 black is dead, dead, dead.

Code: Select all

Searching: 8/1pp1k3/p2p1n1p/5K2/5PPP/8/1P1B4/8 b - - 0 1
infinite: 0 time: 0 increment: 0 moves to go: 0

 1   -0.29   00:00    5061  Kf7 g5 
 2   -1.25   00:00   30672  b6 g5 
 3   -1.35   00:00   66897  Kf7 g5 hxg5 fxg5 Nh5 
 4   -1.32   00:00   96344  Kf7 g5 hxg5 fxg5 
 5   -1.46   00:00  125071  d5 g5 Ne4 Be1 hxg5 
 6   -1.56   00:00  152748  d5 g5 hxg5 fxg5 Ne4 Bf4 
 7   -1.71   00:00  194105  d5 g5 hxg5 fxg5 Ne8 h5 Nd6+ Kg6 
 8   -1.91   00:00  234068  Kf7 g5 hxg5 fxg5 Nh5 g6+ Kg7 Kg5 Ng3 
 9   -1.90   00:00  305300  Kf7 g5 hxg5 fxg5 Nh5 g6+ Kg8 Kg5 Ng3 
10   -2.10   00:00  347464  Ng8 g5 c5 Kg6 hxg5 hxg5 Ke8 f5 Ne7+ Kf6 
11   -1.38   00:00  403122  Kf7 g5 hxg5 fxg5 Nh5 g6+ Kg8 Kg5 Ng3 Bf4 
12   -2.07   00:00  506107  Kf7 g5 Nd7 gxh6 Nf6 Bc3 Nh7 Bg7 b6 Ke4 Ke6 f5+ Kf7 Kd5 
13   -1.85   00:00  584104  Kf7 g5 Nd5 gxh6 b6 Bc3 Nxc3 bxc3 a5 Kg5 Kg8 Kg6 a4 
14   -1.50   00:00  854007  Kf7 g5 Ng8 g6+ Ke7 Bc3 c5 Ba5 b5 h5 b4 Bb6 c4 Bd4 
15   -1.29   00:00   1173K  Kf7 g5 Ng8 g6+ Ke7 Bc3 b6 b3 c5 Bb2 b5 Bg7 b4 Bb2 d5 Ke5 Nf6 f5 
16   -1.90   00:00   1712K  Kf7 g5 Nd5 gxh6 b6 Be1 Nf6 h5 b5 Bc3 Nh7 Ba5 c5 Bb6 Ke7 
17   -1.98   00:00   2208K  Kf7 g5 Nd5 gxh6 b6 Be1 a5 b3 Ne3+ Kg5 Nd5 Bd2 Nf6 Kf5 Nh7 Bc3 Nf8 h5 Nh7 Ke4 Ke6 f5+ Kf7 Kd5 Ng5 
18   -1.62   00:00   2392K  Kf7 g5 Nd5 gxh6 b6 h5 b5 b3 Ne7+ Kg5 Nd5 h7 Kg7 Kf5 Ne7+ Ke6 Nc6 h8=Q+ Kxh8 Kd7 Nd4 
19   -1.73   00:00   4149K  Kf7 g5 Nd5 gxh6 Nf6 h5 Nh7 Be1 d5 Bf2 b6 Bh4 d4 Ke4 c5 Bd8 b5 Bb6 d3 Kxd3 c4+ Kd4 Nf6 Bd8 
20   -1.53   00:00   4520K  Kf7 g5 Nd5 gxh6 Nf6 h5 Nh7 Be1 d5 b4 d4 Ke5 Nf6 Kxd4 Ng4 Kd5 Nxh6 Ke5 Ng8 Bc3 b6 f5 
21   -1.56   00:00   6522K  Kf7 g5 Nd5 gxh6 Nf6 Bb4 Nh7 Bc3 b6 Ke4 c6 f5 a5 b3 Nf6+ Kd3 Ke7 Bd2 Kf7 Kd4 Nh7 Bf4 Kf6 Bxd6 Kxf5 Bc7 
22   -1.34   00:00   8677K  Kf7 g5 Nd5 gxh6 Nf6 h5 Nh7 Bc3 b6 Bd4 c5 Bg7 d5 Ke5 d4 Ke4 a5 Be5 a4 f5 Ng5+ Kd3 b5 Bd6 c4+ Kxd4 Kf6 Kc5 
23   -1.40   00:00  12420K  Kf7 g5 Nd5 gxh6 Nf6 Ba5 b6 Bc3 Nh7 Ke4 Kg6 Kd5 Kxh6 Kc6 Kh5 Kxc7 Kxh4 Kxd6 Kg4 Ke5 a5 f5 a4 f6 Kg5 Ke6 
24   -1.35   00:01  13611K  Kf7 g5 Nd5 gxh6 Nf6 Ba5 b6 Bc3 Nh7 Ke4 Kg6 Kd5 Kxh6 Kc6 Kh5 Kxc7 Kxh4 Kxd6 Kg4 Ke5 a5 f5 a4 Bd4 b5 Bc5 Kg5 Ke6 Kh5 Kd6 Kg5 Kc6 Kxf5 Kxb5 
25   -1.28   00:01  21016K  Kf7 g5 Nd5 gxh6 Nf6 Be1 Nh7 h5 c5 Ba5 b5 Bc7 d5 Bb6 c4 Bd4 b4 Ke5 Nf6 Kd6 a5 Kc5 Ke6 Kb5 b3 Bxf6 
26   -1.14   00:02  29853K  Kf7 g5 Nd5 gxh6 Nf6 Be1 Nh7 Bc3 b6 Ke4 c6 Kf5 a5 b3 Nf8 Kg4 d5 f5 Nh7 Kf4 Nf6 Bd2 Ne4 Be3 b5 Ke5 a4 bxa4 bxa4 Bc1 Nf6 
27   -1.12   00:05  75468K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 g6+ Kf6 Be1 Nxg6+ hxg6 Kxg6 Ke5 d4 Ba5 d3 Ke4 b6 Bc3 Kg5 Kxd3 Kf5 Kc4 Ke6 Bd2 Kd6 Bf4+ Kc6 Kb3 b5 Bd2 Kd5 Kc2 
28   -1.50   00:07 104599K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 b6 Bf4 Ke6 Bc7 b5 h6 Ng6 Bb6 c4 Bxd4 b4 h7 a5 h8=Q Nxh8 Bxh8 a4 
29   -1.54   00:07 107972K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 b6 Bf4 Ke6 Bc7 b5 h6 Ng6 Bb6 d3 Kxd3 c4+ Kc3 Kf5 Be3 Ne5 h7 Nf7 Bd4 Kxg5 h8=Q Nxh8 Bxh8 Kf4 Kd4 
30   -1.67   00:09 133863K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 b5 Bf4 Ke6 Bc7 b4 Bd8 Nf5 Kd3 Kf7 Bc7 Ke6 b3 Ne7 g6 Kf5 Bb6 Ng8 Bxc5 Kg5 Bxd4 Kxh5 g7 Kg6 Kc4 Kf7 Kxb4 Ne7 Kc5 Nf5 
31   -1.63   00:10 143229K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 b5 Bf4 Ke6 Bc7 b4 Bd8 Nf5 Kd3 Kf7 Bc7 Kg8 h6 Kh7 Bb6 Nd6 Bxc5 Nf7 Bxb4 Nxg5 Kxd4 Nf3+ Ke4 Ng5+ Kf5 Nf3 Bf8 Nd2 b4 Nc4 Kf6 Ne3 Kg5 Nd5 Bd6 
32   -1.43   00:12 174502K  Kf7 g5 Nd5 Ke4 c6 gxh6 Nf6+ Kf5 b5 Bc3 Nh7 b3 c5 b4 Nf8 Be1 Nh7 Bd2 Nf6 Bc3 Nh7 h5 Nf8 Bd2 Nh7 Be1 Nf8 Bc3 Nh7 Ke4 cxb4 Bxb4 Nf6+ Kf5 d5 Bc3 
33   -1.71   00:17 239465K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 Ke6 Bf4 b5 Bc7 b4 Bd8 Nf5 Kd3 Kf7 Bc7 Kg8 h6 Kh7 Bb6 Nd6 Bxc5 Nf7 Bxb4 Nxg5 Bd2 Nf3 Bf4 Kg6 Ke4 
34   -1.54   00:21 297777K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 b5 Bf4 Ke6 Bc7 b4 Bd8 Nf5 Kd3 Kf7 Bc7 Kg8 h6 Nh4 Bg3 Nf5 Bf4 Kh7 Ke4 Kg6 h7 Kxh7 Kxf5 c4 g6+ Kg8 Be5 d3 
35   -1.88   00:33 461685K  Kf7 g5 Nd5 Ke4 hxg5 fxg5 Ne7 h5 c5 Kf4 d5 Ke5 d4 Ke4 b5 Bf4 Ke6 Bc7 b4 Bb6 Nf5 h6 Nd6+ Kf4 d3 Ke3 d2 Kxd2 Kf5 Bxc5 Ne4+ Ke2 Nxg5 Bxb4 Kg6 Bd2 Nf7 Kd3 Ne5+ Kd4 Nf3+ Kc3 Kh7 b3 Kg6 Bf4 Ng1 Kc4 Ne2 Bd2 Ng3 Kd4 Nf5+ Kc5 Kh7 Kb6 
36   -1.01   00:48 670563K  Kf7 g5 Nd5 gxh6 Nf6 Ba5 b6 Bc3 Nh7 Ke4 c6 f5 a5 b3 Kg8 Kf4 Kf7 Ke3 Nf6 Kd3 Nh7 Kd4 Kf6 Ke4+ Kf7 Kf4 Ke7 Kf3 Kf7 Be1 Nf6 Bd2 Ke7 Ke3 Kf7 Kd4 Nd7 Kc4 Kg8 Bf4 Kh7 
37   -2.02   01:47   1492M  Kf7 g5 Nd5 h5 Ne7+ Ke4 hxg5 fxg5 c5 Kf4 d5 Ke5 d4 Ke4 b5 Bf4 Ke6 Bc7 b4 Bb6 Nf5 h6 Nd6+ Kf4 d3 Ke3 d2 Ke2 Nf7 Bxc5 Nxg5 Bxb4 d1=R Kxd1 Kf7 Ke2 Kg6 Bd2 Nf7 Kd3 Ne5+ Kd4 Nf3+ Kc3 a5 b3 Ne5 Kd4 Nf3+ Kd3 Ne5+ Ke4 
38   -2.09   02:01   1686M  Kf7 g5 Nd5 h5 Ne7+ Ke4 b5 Bc3 b4 Bxb4 d5+ Kf3 Nf5 Bc5 Ke6 Kg4 d4 Kf3 d3 gxh6 Nxh6 Bf8 Ng4 h6 Nf6 Bg7 Nh7 Ke3 Kf5 Be5 Kg6 Kxd3 Kxh6 Bxc7 Nf6 f5 Ng4 Ke4 Kg7 Be5+ Kf7 Bd4 Nh6 Ke5 Ng4+ Kd6 Nh6 
39   -2.48   02:34   2159M  Kf7 g5 Nd5 h5 Ne7+ Ke4 hxg5 fxg5 c5 Kf4 d5 Ke5 d4 Ke4 b5 Bf4 Ke6 Bc7 b4 Bb6 Nf5 h6 Nd6+ Kf4 d3 Ke3 d2 Kxd2 Kf5 Bxc5 Ne4+ Ke2 Nxg5 Bxb4 Kg6 Bd2 Nf7 Kd3 Ne5+ Kd4 Ng4 Kd5 Kh7 b3 Nf2 Kc6 Kg6 Bf4 Nd3 Be3 Nb4+ Kc5 Nd3+ Kd4 Ne1 Kc4 Kh7 Bf4 Nf3 Kc5 Ne1 Kb6 Nd3 Be3 Nb4 Bd2 
40   -1.72   02:57   2463M  Kf7 g5 Nd5 h5 Ne7+ Ke4 b5 Bc3 d5+ Ke5 hxg5 fxg5 b4 Be1 a5 Kd4 Ke6 Kc5 Nf5 h6 Kf7 Kxd5 Kg6 Bd2 c6+ Kc5 Ng3 Be3 Ne4+ Kd4 Ng3 b3 Ne2+ Kc5 Nc3 Bc1 Ne2 Bd2 a4 Kxb4 axb3 Kxb3 Ng3 
41   -1.74   03:08   2618M  Kf7 g5 Nd5 h5 Ne7+ Ke4 b5 Bc3 d5+ Ke5 hxg5 fxg5 b4 Be1 a5 Kd4 Kg7 Kc5 Kg8 Kb5 Nf5 Kxa5 Ng7 h6 Ne6 Bd2 Kh7 Kb5 Nd4+ Kxb4 Kg6 Bc3 Ne6 Bf6 c6 Kc3 Kh7 Be7 Kg6 Kd3 Kh7 b4 Kg6 Bf6 Kh7 Kc2 c5 b5 Kg6 b6 Nxg5 
42   -2.12   04:18   3574M  Kf7 g5 Nd5 h5 Ne7+ Ke4 c6 Bc3 d5+ Ke5 hxg5 fxg5 c5 Bd2 d4 Ke4 b6 Bf4 Ke6 Bh2 b5 Bc7 Nf5 h6 Ne7 Bb6 d3 Kxd3 c4+ Ke4 Kf7 Bc5 Ng6 Bd4 Kg8 Kf5 Kh7 Bc3 Nh4+ Kg4 Ng6 Bb4 Kg8 Kf3 Ne5+ Ke4 Ng6 Ba5 Ne7 Bd8 Ng6 Kf5 Kh7 Ba5 Nh4+ Kf6 Ng6 Bd2 Nh8 Kf5 Ng6 Bb4 Nh4+ Kf6 Ng6 Kf7 Nf4 
43   -2.19   04:29   3730M  Kf7 g5 Nd5 h5 Ne7+ Ke4 c6 Bc3 d5+ Ke5 hxg5 fxg5 c5 Bd2 d4 Ke4 Ke6 Bf4 b5 Bc7 Nd5 h6 Ne7 Bb6 d3 Kxd3 c4+ Ke4 Kf7 Bc5 Ng6 Bd4 Kg8 Kf5 Kh7 Bc3 Nh4+ Kg4 Ng6 Bb4 Kg8 Kf3 Kh7 Ke4 Kg8 Ba5 Ne7 Bd8 Ng6 Kf5 Nh4+ Kf6 Kh7 Ba5 Ng6 Kf7 Nh4 Bc3 Ng6 Ke6 Nf4+ Kf5 Ng6 Bb4 Nh4+ Kf6 Ng6 Ke6 Nh4 
44   -2.10   04:37   3848M  Kf7 g5 Nd5 h5 Ne7+ Ke4 c6 Bc3 d5+ Ke5 hxg5 fxg5 c5 Bd2 d4 Ke4 b6 Bf4 Ke6 Bh2 b5 Bc7 Nd5 h6 Ne7 Bb6 d3 Kxd3 c4+ Ke4 Kf7 Bc5 Ng6 Bb4 Kg8 Bc3 Ne7 Bd4 Kh7 Bf6 Ng6 Bc3 Ne7 Kd4 Ng6 Kd5 Nf4+ Ke5 Ne2 Kf6 Nf4 Bd2 Ng6 Ke6 Nf8+ Kf5 Ng6 Bc3 Nh4+ Kf6 Ng6 Kf7 Nh4 Ba5 Ng6 Ke6 Nf4+ Kf5 Ng6 Bd8 
45   -2.05   05:23   4464M  Kf7 g5 Nd5 h5 Ne7+ Ke4 c6 Bc3 d5+ Ke5 hxg5 fxg5 c5 Bd2 d4 Ke4 b6 Bf4 Ke6 Bh2 b5 Bc7 Nd5 h6 Ne7 Bb6 d3 Kxd3 c4+ Ke4 Kf7 Bc5 Ng6 Bb4 Kg8 Bc3 Ne7 Bd4 Kh7 Bf6 Ng6 Bc3 Ne7 Kd4 Ng6 Kd5 Nf4+ Ke5 Ne2 Kf6 Nf4 Bd2 Ng6 Ke6 Nf8+ Kf5 Ng6 Bc3 Nh4+ Kf6 Ng6 Kf7 Nh4 Bd2 Ng6 Be1 Nf4 Bg3 Ng6 Bd6 a5 Bc7 b4 Bxa5 
46   -2.00   05:50   4837M  Kf7 g5 Nd5 h5 Ne7+ Ke4 c6 Bc3 d5+ Ke5 hxg5 fxg5 c5 Bd2 d4 Ke4 b5 Bf4 Ke6 Bc7 Nd5 h6 Ne7 Bb6 d3 Kxd3 c4+ Ke4 Kf7 Bc5 Ng6 Bb4 Kg8 Be1 Ne7 Bc3 Kh7 Kd4 Ng6 Kd5 Nh4 Ke4 Kg6 Bb4 Ng2 Bd2 Nh4 Kf4 Kh7 Bc3 Ng6+ Kf5 Ne7+ Kf6 Ng6 Bb4 Nf4 Kf5 Ng6 Kg4 Kg8 Bd2 Kh7 Kh5 Nf8 Bf4 Ng6 Bd6 
Nodes: 4837296853
Nodes/second: 13785832
Best move: Kf7
Ponder move: g5

[Dann Corbit]

Analysis records for the end of the game, going backwards:

Code: Select all

5n1k/1pp2K1P/p5P1/8/3p4/8/1P1B4/8 b - - acd 11; acs 0; bm Ne6; move 47b; ce -32757; dm -5; pm Ne6; pv Ne6 Kxe6 Kg7 Bf4 d3 h8=Q+ Kxh8 Kf7 b5 Be5+;
5n1k/1pp4P/p3K1P1/8/3p4/8/1P1B4/8 w - - acd 13; acs 0; bm Kf7; c3 "Kf7"; move 47a; ce 32756; dm 6; pm Kf7; pv Kf7 Ne6 Kxe6 Kg7 Bf4 d3 h8=Q+ Kxh8 Kf7 b5 Be5+;
7k/1ppn3P/p3K1P1/8/3p4/8/1P1B4/8 b - - acd 15; acs 0; bm Kg7; c3 "Nf8+"; move 46b; ce -32753; dm -7; pm Kg7; pv Kg7 Kxd7 Kxg6 h8=Q Kf5 Qxd4 a5 Qf4+ Kg6 Ke6 Kh7 Qf7+ Kh8 Bc3+;
7k/1ppn3P/p5P1/5K2/3p4/8/1P1B4/8 w - - acd 17; acs 0; bm Ke6; c3 "Ke6"; move 46a; ce 32752; dm 8; pm Ke6; pv Ke6 Kg7 Kxd7 Kxg6 h8=Q Kf5 Qxd4 a5 Qf4+ Kg6 Ke6 Kh7 Qf7+ Kh8 Bc3+;
6k1/1ppn3P/p5P1/5K2/3p4/8/1P1B4/8 b - - acd 17; acs 0; bm Kh8; c3 "Kh8"; move 45b; ce -32751; dm -8; pm Kh8; pv Kh8 Ke6 Kg7 Kxd7 Kxg6 h8=Q Kf5 Qxd4 a5 Qf4+ Kg6 Ke6 Kh7 Qf7+ Kh8 Bc3+;
6k1/1ppn4/p5PP/5K2/3p4/8/1P1B4/8 w - - acd 19; acs 0; bm h7+; c3 "h7+"; move 45a; ce 32750; dm 9; pm h7+; pv h7+ Kh8 Ke6 Kg7 Kxd7 Kxg6 h8=Q Kf5 Qxd4 a5 Qf4+ Kg6 Ke6 Kh7 Qf7+ Kh8 Bc3+;
5k2/1ppn4/p5PP/5K2/3p4/8/1P1B4/8 b - - acd 19; acs 2; bm Ke7; c3 "Kg8"; move 44b; ce -32749; dm -9; pm Ke7; pv Ke7 h7 Kd6 h8=Q Kc5 g7 Nb6 Qf8+ Kc4 g8=Q+ Nd5 Qa3 c6 Ke4 a5 b3+ Kb5 Qxa5+;
5k2/1ppn4/p5P1/5K1P/3p4/8/1P1B4/8 w - - acd 21; acs 0; bm h6; c3 "h6"; move 44a; ce 32748; dm 10; pm h6; pv h6 Ke7 h7 Kd6 h8=Q Kc5 g7 Nb6 Qf8+ Kc4 Qa3 Nd5 g8=Q c6 Ke4 a5 b3+ Kb5 Qxa5+;
5k2/1ppn4/p5P1/3p1K1P/8/8/1P1B4/8 b - - acd 149; acs 24; bm Kg8; c3 "d4"; move 43b; ce -32619; dm -74; pm Kg8; pv Kg8 Bf4 c5 h6 Nf8 Bd6 Nh7 gxh7+ Kxh7 Bxc5 a5 Ke5 d4 Kxd4 Kg8 Kc4 Kf7 Kb5 a4 Kxa4 Kg6 b3 Kh7 b4 Kg8 b5 Kh7 Ka3 Kg6 h7 Kf5 b6 Kg5 h8=Q Kg4 Qg7+ Kf3 Qxb7+ Kg4;
5k2/1ppn4/p5P1/3p1K2/7P/8/1P1B4/8 w - - acd 151; acs 0; bm h5; c3 "h5"; move 43a; ce 32618; dm 75; pm h5; pv h5 Kg8 Bf4 c5 h6 Nf8 Bd6 Nh7 gxh7+ Kxh7 Bxc5 a5 Ke5 d4 Kxd4 Kg8 Kc4 Kf7 Kb5 a4 Kxa4 Kg6 h7 Kg7 h8=B+ Kf7 b3 Ke6 b4 Kf5 b5 Kg4 Ka5 Kf5 Kb6 Kg4 Kxb7 Kh5 b6 Kg5;
8/1pp1k3/p2p1n1p/5K2/5PPP/8/1P1B4/8 b - - acd 46; acs 350; bm Kf7; c3 "d5"; move 39b; ce -200; pm Kf7; pv Kf7 g5 Nd5 h5 Ne7+ Ke4 c6 Bc3 d5+ Ke5 hxg5 fxg5 c5 Bd2 d4 Ke4 b5 Bf4 Ke6 Bc7 Nd5 h6 Ne7 Bb6 d3 Kxd3 c4+ Ke4 Kf7 Bc5 Ng6 Bb4 Kg8 Be1 Ne7 Bc3 Kh7 Kd4 Ng6 Kd5 Nh4 Ke4 Kg6 Bb4 Ng2 Bd2 Nh4 Kf4 Kh7 Bc3 Ng6+ Kf5 Ne7+ Kf6 Ng6 Bb4 Nf4 Kf5 Ng6 Kg4 Kg8 Bd2 Kh7 Kh5 Nf8 Bf4 Ng6 Bd6;

[Dan Astrachan]

I pitted SF with default contempt against SF with contempt 0 to see what would happen after 41.h5.
Time control : 2 hours + 30 seconds per move
Result : White wins

[pgn][Event "?"] [Site "?"] [Date "2018.12.03"] [Round "?"] [White "Stockfish_x64_03122018_C=21"] [Black "Stockfish_x64_03122018_C=0"] [Result "1-0"] [ECO "C26"] [Opening "Vienna"] [PlyCount "129"] [Termination "adjudication"] [TimeControl "7200+30"] [Variation "Paulsen-Mieses Variation"] 1. e4 {book} e5 {book} 2. Nc3 {book} Nf6 {book} 3. g3 {book} Bc5 {book} 4. Bg2 {book} O-O {book} 5. Nge2 {book} d6 {book} 6. O-O {book} Nc6 {book} 7. d3 {book} Be6 {book} 8. Nd5 {book} Bxd5 {book} 9. exd5 {book} Ne7 {book} 10. Bg5 {book} Nd7 {book} 11. d4 {book} exd4 {book} 12. Nxd4 {book} h6 {book} 13. Be3 {book} Ne5 {book} 14. Qe2 {book} Qd7 {book} 15. h3 {book} Rae8 {book} 16. Rae1 {book} a6 {book} 17. f4 {book} N5g6 {book} 18. Qf2 {book} Bxd4 {book} 19. Bxd4 {book} Nf5 {book} 20. Bc3 {book} Rxe1 {book} 21. Rxe1 {book} Re8 {book} 22. Bf3 {book} Rxe1+ {book} 23. Qxe1 {book} Nfe7 {book} 24. Kg2 {book} Qa4 {book} 25. Qd2 {book} Qxa2 {book} 26. Qd4 {book} f6 {book} 27. Qe4 {book} Qb1 {book} 28. h4 {book} Kf8 {book} 29. Bh5 {book} f5 {book} 30. Qd4 {book} Qxc2+ {book} 31. Kh3 {book} Qe4 {book} 32. Qxg7+ {book} Ke8 {book} 33. Bxg6+ {book} Kd7 {book} 34. Bxf5+ {book} Qxf5+ {book} 35. Qg4 {book} Qxg4+ {book} 36. Kxg4 {book} Nxd5 {book} 37. Bd2 {book} Nf6+ {book} 38. Kf5 {book} Ke7 {book} 39. g4 {book} Kf7 {book} 40. g5 {book} Nd5 {book} 41. h5 {book} Ne7+ {-1.98/35 550s} 42. Ke4 {+1.89/35 639s} hxg5 {-2.45/37 839s} 43. fxg5 {+2.00/33 111s} c5 {-2.45/39 344s} 44. Kf4 {+12.49/39 1868s} d5 {-1.79/38 173s} 45. Ba5 {+14.12/29 110s} Kg7 {-24.87/32 1699s} 46. Bd8 {+25.68/29 105s} Ng8 {-153.62/34 1303s} 47. Bb6 {+153.78/30 223s} c4 {-153.75/32 178s} 48. Bd4+ {+153.81/34 107s} Kf7 {-153.82/32 236s} 49. g6+ {+153.85/35 114s} Kf8 {-153.82/32 124s} 50. Kg5 {+153.86/41 95s} a5 {-153.85/33 100s} 51. h6 {+153.88/41 196s} Nxh6 {-153.87/36 57s} 52. Kxh6 {+M45/35 90s} Kg8 {-153.89/38 97s} 53. Bc3 {+M39/40 84s} a4 {-153.90/40 50s} 54. Kg5 {+M37/41 87s} Kf8 {-M34/45 622s} 55. Kf5 {+M35/43 111s} Kg8 {-M32/45 93s} 56. Kf6 {+M31/45 211s} b6 {-M30/48 43s} 57. Bd4 {+M29/47 67s} b5 {-M28/48 111s} 58. Bc5 {+M27/46 94s} d4 {-M26/50 66s} 59. Bxd4 {+M23/50 129s} b4 {-M22/53 54s} 60. Bc5 {+M21/53 115s} a3 {-M20/61 80s} 61. bxa3 {+M19/69 95s} b3 {-M18/72 54s} 62. Bd4 {+M17/81 79s} Kf8 {-M16/42 41s} 63. g7+ {+M15/45 119s} Kg8 {-M14/52 80s} 64. Bc3 {+M13/53 230s} b2 {-M12/127 23s} 65. Bxb2 {+M11/127 5.0s, White wins by adjudication: SyzygyTB} 1-0 [/pgn]

[zullil]

The main problem with SF recognizing the problem is that d5 is a much worse response than Kf7. Yes, black is in big trouble.
But after 39.. d5 black is dead, dead, dead.

Actually, both moves 39 were subpar. White's 39. g4 is inferior to Kg6:

+9.16 39. Kg6 Ng4 40. f5 d5 41. Bb4+ Ke8 42. Kg7 h5 43. Bc3 Ne3 44. Kg6 Nc4 45. f6 Nd6 46. Be5 Kf8 47. b3 Nf7 48. Bxc7 d4 49. Kxh5 d3 50. Ba5 Ne5 51. g4 Nf3 52. g5 d2 53. g6 d1=Q 54. Bb4+ Ke8 55. f7+ Kd7 56. f8=Q Nd4+ 57. Kh6 Qg4 58. Qe7+ Kc8 59. Qg5 Nf5+ 60. Kh7 Qh3 61. h5 b6 62. h6 a5 63. Bf8 Kb7 64. Qf6 Ka6 65. Qc6 Ka7 66. Qe6 Qd3 67. Kh8 Nxh6 68. Bxh6 Qd8+ 69. Kh7 Qd3 70. Qf7+ Ka8 71. Qc7 Qxb3 72. g7 (depth 40, 0:05:35)

[peter]

I pitted SF with default contempt against SF with contempt 0 to see what would happen after 41.h5.
Time control : 2 hours + 30 seconds per move
Result : White wins

[pgn][Event "?"] [Site "?"] [Date "2018.12.03"] [Round "?"] [White "Stockfish_x64_03122018_C=21"] [Black "Stockfish_x64_03122018_C=0"] [Result "1-0"] [ECO "C26"] [Opening "Vienna"] [PlyCount "129"] [Termination "adjudication"] [TimeControl "7200+30"] [Variation "Paulsen-Mieses Variation"] 1. e4 {book} e5 {book} 2. Nc3 {book} Nf6 {book} 3. g3 {book} Bc5 {book} 4. Bg2 {book} O-O {book} 5. Nge2 {book} d6 {book} 6. O-O {book} Nc6 {book} 7. d3 {book} Be6 {book} 8. Nd5 {book} Bxd5 {book} 9. exd5 {book} Ne7 {book} 10. Bg5 {book} Nd7 {book} 11. d4 {book} exd4 {book} 12. Nxd4 {book} h6 {book} 13. Be3 {book} Ne5 {book} 14. Qe2 {book} Qd7 {book} 15. h3 {book} Rae8 {book} 16. Rae1 {book} a6 {book} 17. f4 {book} N5g6 {book} 18. Qf2 {book} Bxd4 {book} 19. Bxd4 {book} Nf5 {book} 20. Bc3 {book} Rxe1 {book} 21. Rxe1 {book} Re8 {book} 22. Bf3 {book} Rxe1+ {book} 23. Qxe1 {book} Nfe7 {book} 24. Kg2 {book} Qa4 {book} 25. Qd2 {book} Qxa2 {book} 26. Qd4 {book} f6 {book} 27. Qe4 {book} Qb1 {book} 28. h4 {book} Kf8 {book} 29. Bh5 {book} f5 {book} 30. Qd4 {book} Qxc2+ {book} 31. Kh3 {book} Qe4 {book} 32. Qxg7+ {book} Ke8 {book} 33. Bxg6+ {book} Kd7 {book} 34. Bxf5+ {book} Qxf5+ {book} 35. Qg4 {book} Qxg4+ {book} 36. Kxg4 {book} Nxd5 {book} 37. Bd2 {book} Nf6+ {book} 38. Kf5 {book} Ke7 {book} 39. g4 {book} Kf7 {book} 40. g5 {book} Nd5 {book} 41. h5 {book} Ne7+ {-1.98/35 550s} 42. Ke4 {+1.89/35 639s} hxg5 {-2.45/37 839s} 43. fxg5 {+2.00/33 111s} c5 {-2.45/39 344s} ... [/pgn]

After Backward or your game, Dan, I get this output at the position after 42...hxg5 (?) with 6men Sygygys:
[d]8/1pp1nk2/p2p4/6pP/4KP2/8/1P1B4/8 w - - 0 1
Analysis by Cfish 241118 64 POPCNT NUMA:
43.fxg5 c5 44.g6+ Kf6 45.Kf4 d5 46.Ba5 Nc6 47.Be1 d4 48.Bh4+ Ke6 49.h6 d3 50.h7 d2 51.g7 d1Q 52.g8Q+ Kd6 53.h8Q Kc7 54.Qc3 Qf1+ 55.Kg4 Qd1+ 56.Kg5 b5 57.Qxc5 Qd2+ 58.Kh5 Qe2+ 59.Kh6 Qd2+ 60.Qgg5 Qxg5+ 61.Kxg5 b4 62.Qc4 Kb7 63.Qf7+ Ka8 64.Bg3 Ne7 65.Qxe7
+- (16.56) Depth: 32/61 00:03:57 8490MN, tb=22891701

After Backward of this line,
39.h5 Kf7 40.g5 Nd5 41.h5 Ne7+ 42.Ke4 c6 43.Bc3 d5+ 44.Ke5 hxg5 45.fxg5 c5 46.Bd2 d4 47.Ke4 b5 instead of ...Ke6 in the final output- line,
TommyTC gave there:
http://talkchess.com/forum3/viewtopic.p ... 36#p781136
and 42...c6: (instead of your game's 42...hxg5 (?) :
[d]8/1p2nk2/p1pp3p/6PP/4KP2/8/1P1B4/8 w - - 0 1
Analysis by Cfish 241118 64 POPCNT NUMA:
43.Be1 b6 44.Bh4 hxg5 45.fxg5 a5 46.Bg3 Ke6 47.Kf3 a4 48.Kg4 b5 49.g6 b4 50.Be1 Kf6 51.Bxb4 Nxg6 52.Bxd6 Nh8 53.Bc5 Nf7 54.Bd4+ Ke6 55.Kf4 Nh6 56.Be5 Nf5 57.Bc3 Nh6
= (0.00) Depth: 51/45 00:04:34 6840MN, tb=58084033

To get the 0.00- eval into hash, you'll probably have to go about to move nr.60, but then it can be kept in hash backward easily and quickly.
The last 3 plies backward to 47.h5 (?) are no problem anymore neither, after that an 47.h5:
[d]8/1pp2k2/p2p3p/3n1KPP/5P2/8/1P1B4/8 b - - 0 1
Analysis by Cfish 241118 64 POPCNT NUMA:
41...Ne7+ 42.Kg4 c5 43.gxh6 Ng8 44.f5 Nf6+ 45.Kf3 b5 46.Bf4 d5 47.Be5 d4 48.Bxf6 Kxf6 49.h7 Kg7 50.Ke4 a5 51.h8R Kxh8 52.f6 Kh7 53.Kf5 d3 54.f7 d2 55.f8Q d1Q 56.Qf7+ Kh8 57.Qf6+ Kh7 58.Qg6+ Kh8 59.Qh6+ Kg8 60.Qe6+ Kh7 61.Qg6+
= (0.00) Depth: 50/41 00:01:09 1807MN, tb=14803443

So in your game 41...hxg5 is the game- losing blunder.

[peter]

Actually, both moves 39 were subpar. White's 39. g4 is inferior to Kg6:

That's right, Louis, but it wasn't the theme of TommyTC's thread starting, yet it's worth to mention too.

[TommyTC]

@Dann Corbit, I agree that Stockfish sees by depth 35 or so that 39...d5?? is losing.

@zullil, yes, 39. g4 was clearly subpar and SF easily sees the win after 39. Kg6. In the article I got this game from I was surprised that that wasn't pointed out, especially since it's not easy to see the win after 39. g4 Kf7 40. g5 Nd5.

@Dan Astrachan and @peter. Peter, you are correct. Before my first posting, I had analyzed 42...c6 as equal after analyzing the replies: 43. Bc3, 43. Be1, and 43. Ba5. And you are also correct that it takes some time, or going down the drawing variation paths, to get the deeply drawn positions in the hash table. By the way, this method of analyzing (going down a path to get a more accurate eval into the hash table) isn't always foolproof.

One of the real points of this thread is that Stockfish at depth 78, and using the full 6 piece EGTB has a blunder on ply 4 in the PV. The move 41. h5? changes the position from a win to a draw, but SF sometimes thinks the variation with 41. h5 evaluates as high as +2.90.

The problem for SF is that while analyzing the position after 39. g4 it thinks this position (drawn)…

[d]8/1pp1nk2/p2p3p/6PP/4KP2/8/1P1B4/8 b - - 0 42

...is better than this one (winning):

[d]8/1pp1nk2/p2p3p/5PP1/4K2P/8/1P1B4/8 b - - 0 42