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Re: What's up with this endgame?

Posted: Tue Jul 23, 2019 10:07 am
by zullil
Ovyron wrote:
Tue Jul 23, 2019 8:38 am

I'm not a believer of such scoring, if the position at move 40 is a mate for white, then surely it should show 100% for white. Then we'd know if at some point White gave up the win, and black gave up the draw with 53 gxf4, which would lead to another 100% score for white.
Well, engines don't have access to 14-man endgame tables. :wink: So they produce approximate evaluations to guide their searches.

Re: What's up with this endgame?

Posted: Tue Jul 23, 2019 2:56 pm
by todd
Zenmastur wrote:
Tue Jul 23, 2019 9:40 am
You were lost after 38. .... Bxb4. If your opponent would have played 39.Kd1! the game was effectively over.
I agree that Kd1 is a better move.

However, what actually changes after Kf2? I have not looked at this in depth, only for a few minutes.

In either case, white is marching the king to the queenside and playing for zugzwang, but after Kf2 black has a little more time to do... something. What does black do, though?

Re: What's up with this endgame?

Posted: Tue Jul 23, 2019 3:15 pm
by todd
MikeB wrote:
Tue Jul 23, 2019 4:51 am
My impressions and with using some backward analysis, you had totally equalize with move 28. Bd6 - always a good time to offer draw here ;>)

The first weakness was 29 ...b5 which allowed Qa5, the next series of moves are pretty much straight foward, but 36.. Ra1 was not the best move I'm afraid. After that everything was more or less forced until you get to 39. Kf2 by white, 39. Kd1 would have been faster . At this point, it appears you were lost, but if there was any doubt, you were certainly lost after 53 gxf4. That move alone change the scoring % from under 60% to over 70% for white. When one gets over 70% in a ICCF game, the winning side should expect to to win. The game was well played, you were a little bit unlucky in some respects and the position required some very deep analysis that is always much easier to see after the fact using backward analysis. Congrats on your unbeaten streak , that's an accomplishment!


Thanks for highlighting the position after 28...Bd6. I'm actually going to use this (and the subsequent dozen moves or so) in my coaching practice as I think it's pretty instructive. The kingside pawn structure is mostly fixed with black weaknesses on light squares.

So it is already white's dream to find a way to exchange all the pieces except the light squared bishops.

Black trading everything except the dark squared bishops is not as promising, since there is only one weakness (e3) rather than black's two (d5 and either f5 or g6). Also black's king is a little safer. So black should probably be keeping pieces on the board, in general. However, trading the heavy pieces and keeping BB vs BN (or trading into an opposite color bishop endgame) should be OK too, if you have to.

It seems this is one of those positions that is getting increasingly rarer these days, where human chess knowledge is useful, even if you have a computer's help.

Re: What's up with this endgame?

Posted: Tue Jul 23, 2019 3:21 pm
by Uri Blass
Ovyron wrote:
Tue Jul 23, 2019 8:38 am
MikeB wrote:
Tue Jul 23, 2019 4:51 am
My impressions and with using some backward analysis, you had totally equalize with move 28. Bd6 - always a good time to offer draw here ;>)
Thanks Mike, I had a score that was positive for black, higher than what white gets on the opening position (maybe it was wrong, but that's what I thought.) I have many games won from the black side, because if your opponent plays bad enough to allow you to equalize, it may play bad enough to let you win, so I only offer draw in trivially drawn positions.
MikeB wrote:
Tue Jul 23, 2019 4:51 am
At this point, it appears you were lost, but if there was any doubt, you were certainly lost after 53 gxf4. That move alone change the scoring % from under 60% to over 70% for white.
I'm not a believer of such scoring, if the position at move 40 is a mate for white, then surely it should show 100% for white. Then we'd know if at some point White gave up the win, and black gave up the draw with 53 gxf4, which would lead to another 100% score for white.
You are right not to offer a draw in equal positions but I do not understand 29...b5
Not sure if it is the losing move but 29...a5 seems better.

A short analysis to depth 36 with contempt 0 does not put 29...b5 in the best 5 moves(29...Rh7 is the 5th line with 0.18 pawns for white).

FEN: 2q5/p2b2k1/1p1b1ppr/3p1p2/3P1P2/P2BPN2/1P3KP1/4QR2 b - - 3 29

Stockfish_19071415_x64_modern:
36/55 05:36 1,050,117k 3,125k -0.18 29. ... Rh7 30.Qa1 Ba4 31.Ng1 Rh8 32.Ne2 Rh2 33.Qa2 Bc6 34.Ng1 Rh1 35.Qb3 Qb7 36.Nf3 Rxf1+ 37.Bxf1 Bd7 38.Ne1 Qc6 39.Bd3 Be8 40.Be2 Bd7 41.Nc2 a5 42.Ne1 Be7 43.Bd3 Bd6 44.a4 Be6 45.Bb5 Qb7 46.Qc2 Bd7 47.Nd3 Bxb5 48.axb5 Kf7
36/51 05:36 1,050,117k 3,125k 0.00 29. ... Rh8 30.Rh1 Rxh1 31.Qxh1 b5 32.Qd1 a5 33.Qb3 Qc6 34.Ne1 b4 35.a4 Be7 36.Bb5 Qb7 37.Be2 Qc6 38.Nf3 Be6 39.Qd1 Bd7 40.Bb5 Qb7 41.Bxd7 Qxd7 42.Qc2 Bd6 43.Nh4 Qc7 44.Qxc7+ Bxc7 45.Nf3 Kf7 46.Nd2 Bd8 47.Nb3 Ke7 48.Ke2 Kd6 49.Ke1 Bb6 50.Kf2 Ke6 51.Ke2 Kf7 52.Kd2
36/56 05:36 1,050,117k 3,125k 0.00 29. ... Rh5 30.Qb1 a5 31.Rc1 Qb7 32.Rh1 Rxh1 33.Qxh1 b5 34.Nh4 b4 35.a4 Qc7 36.Qd1 Qb8 37.Qb3 Bc6 38.Qc2 Be8 39.Qb3
36/55 05:36 1,050,117k 3,125k 0.00 29. ... a6 30.Qb1 a5 31.Rc1 Qb7 32.Rh1 Rxh1 33.Qxh1 Qc7 34.Qd1 b5 35.Ne1 b4 36.a4 Qc6 37.Bb5 Qb7 38.Bxd7 Qxd7 39.Qc2 Kf7 40.Nd3 Ke7 41.Nc5 Qc6 42.Ke2 Kf7 43.Qc1 Be7 44.Kd2 Kg7 45.Qc2 Kf7
36/45 05:36 1,050,117k 3,125k 0.00 29. ... a5 30.Qb1 Rh8 31.Rh1 Rxh1 32.Qxh1 b5 33.Qd1 a4 34.Be2 Qc7 35.Ne1 b4 36.axb4 Bxb4 37.Nd3 Bd6 38.Qd2 Be7 39.Nc1 Be6 40.Bf3 Qc4 41.Qd1 Bd7 42.Be2 Qc7

Re: What's up with this endgame?

Posted: Tue Jul 23, 2019 3:59 pm
by MikeB
Ovyron wrote:
Tue Jul 23, 2019 8:38 am
MikeB wrote:
Tue Jul 23, 2019 4:51 am
My impressions and with using some backward analysis, you had totally equalize with move 28. Bd6 - always a good time to offer draw here ;>)
Thanks Mike, I had a score that was positive for black, higher than what white gets on the opening position (maybe it was wrong, but that's what I thought.) I have many games won from the black side, because if your opponent plays bad enough to allow you to equalize, it may play bad enough to let you win, so I only offer draw in trivially drawn positions.
The smiley meant I was joking - you were absolutely correct to keep playing for the reasons you stated. Even in ICCF people make mistakes on occasion.

Re: What's up with this endgame?

Posted: Tue Jul 23, 2019 4:05 pm
by Zenmastur
todd wrote:
Tue Jul 23, 2019 2:56 pm
Zenmastur wrote:
Tue Jul 23, 2019 9:40 am
You were lost after 38. .... Bxb4. If your opponent would have played 39.Kd1! the game was effectively over.
I agree that Kd1 is a better move.

However, what actually changes after Kf2? I have not looked at this in depth, only for a few minutes.

In either case, white is marching the king to the queenside and playing for zugzwang, but after Kf2 black has a little more time to do... something. What does black do, though?
The white king is going in the wrong direction if Kf2 is played. It loses at least 2 moves which gives black chances to organize a defense on the queen side. But like most losses this one isn't caused by one move. The are several questionable moves. I always like to nip a problem in the bud before it has any chance to do major damage. So I suggest he should have played 36. ... g5. I admittedly haven't looked at this move very deeply but it does seem to solve most of the problems of the position. The only problem I see with this move is that blindly playing it will NOT stop you from playing the same losing moves as was played in the game at some later time. You could transpose back in to the losing lines if you were unaware of what the problem with the position is.

I haven't slept yet and am nodding off so I'm off to bed!

Regards,

Zenmastur

Re: What's up with this endgame?

Posted: Wed Jul 24, 2019 7:07 am
by Ovyron
zullil wrote:
Tue Jul 23, 2019 10:07 am
Well, engines don't have access to 14-man endgame tables. :wink: So they produce approximate evaluations to guide their searches.
I'm quite happy with a +8.00 score for the position in the OP. I just can't reproduce it, and I wonder if it's because of my lack of 6-men tablebases (can people show big score with just 5-men?) If so, this might be the very first game I see in my life where 6-men tablebases would have made a difference.

However, a score of 70% doesn't tell me anything, because performance in a position requires two different percentages, % of side with advantage winning, and % of game ending as draw. With 0% of game being drawn, 70% means 30% of black winning the game. With 30% drawn it means 0% of black winning the game. 70% White win 0% Draw 30% Black is significantly worse than 70% White win 30% Draw 0% Black win, I'd even take 55% White win 45% Draw 0% Black Win over 30% Black win depending on the circumstances.

See what I mean? If in a position White wins 65% Draw 45% Black wins 0% is a lot more desirable than White 66% Draw 0% Black wins 44% (that's 44% of losing the game!) White's % isn't helping me to make choices.
Uri Blass wrote:
Tue Jul 23, 2019 3:21 pm
You are right not to offer a draw in equal positions but I do not understand 29...b5
Back when I played this game I was using a "full arsenal" of engines analysis method. I analyzed this position with Stockfish and derivatives, Komodo, Houdini, Rybka, Texel, Shredder and Critter.

Back when I reached this position, I held that black had a slight edge, and this was the same analysis method that helped me equalize the game and get a small edge as black against my opponent. I was desperate to not lose that edge.

So there's a critical answer by white that kills black's edge for most of the moves: 30.Rh1!! After 30.Rh1 black is forced to exchange rooks, killing all of black's chance for winning.

After 29...a5 then 30.Rh1!! And the position is 0.00 with no chance for black to win, ever.

Of course, 30.Rh1!! is so strong, that even after 29...b5!! 30.Rh1!! we get the same thing, but after 29...b5 White wants to play 30.Qa5 so badly, that black's rook is saved. That's the entire point of b5 (only move where black doesn't lose its edge.)

After 29...b5!! 30.Qa5!? Komodo still likes the black side:



-----
15 0:02 -0.19 30...a6 31.Qd2 Rh8 32.b4 Qe8 33.Qc1 Qe7 34.Rh1 Qd8 35.Rxh8 Qxh8 36.Ke2 Qd8 37.Qh1 Qc8 38.Qh4 (5.328.823) 2314
15 0:02 -0.02 30...Qb8 31.Rb1 Rh8 32.Rc1 Re8 33.Rh1 Rc8 34.Nd2 Qb6 35.Nb3 Qxa5 36.Nxa5 Rc7 37.Kf3 b4 38.axb4 Bxb4 39.Nb3 (5.329.000) 2314
15 0:02 0.00 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nf3 Qb7 (5.329.053) 2314
15 0:02 +0.17 30...Qc7 31.Qxc7 Bxc7 32.Nd2 a6 33.Rc1 Bd6 34.Nb3 g5 35.Kf3 Rh8 36.Na5 gxf4 37.Nb7 Bb8 38.Nc5 Bc8 39.exf4 Rh4 40.Re1 Rxf4+ (5.329.097) 2314
-----
16 0:03 -0.06 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Rc1 Bd7 34.Nd2 g5 35.fxg5 fxg5 36.Nb3 Rh8 37.Nc5 Bc8 38.b4 Kg6 39.Nb3 Bb7 40.Nc5 (7.797.905) 2275
16 0:03 -0.02 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nf3 Re8 34.Rh1 Rc8 35.Nd2 Qb6 36.Nb3 Qxa5 37.Nxa5 Rc7 38.Kf3 b4 39.axb4 Bxb4 (7.802.886) 2274
16 0:03 0.00 30...Qb8 31.Rb1 Rh8 32.Rc1 Re8 33.Rh1 Rc8 34.Nd2 Qb6 35.Nb3 Rc7 36.Qd2 Rc8 37.Qa5 (7.802.938) 2274
16 0:03 +0.33 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Rc1 Bd6 34.fxg5 fxg5 35.Nb3 a6 36.Nc5 Bc8 37.a4 f4 38.e4 bxa4 39.Nxa4 dxe4 40.Bxe4 Bg4 41.Rc6 (7.802.994) 2274
-----
17 0:07 -0.11 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nf3 Rh5 34.Qa6 Rh6 35.Qa5 Rh8 36.Qa6 Re8 37.g3 Re6 38.Qa5 b4 39.axb4 Qe8 (17.579.148) 2332
17 0:07 -0.11 30...Qb8 31.Rb1 Rh8 32.Rc1 Rh5 33.Qa6 Rh6 34.Qa5 Rh8 35.Qa6 Re8 36.g3 Re6 37.Qa5 b4 38.axb4 Qe8 39.Qxd5 (17.579.239) 2332
17 0:07 +0.01 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Rc1 Bd7 34.Nd2 g5 35.fxg5 fxg5 36.Nb3 f4 37.e4 dxe4 38.Bxe4 Kf6 39.Nc5 Bf5 40.Bxf5 Kxf5 41.Re1 g4 42.Nxa6 (17.579.264) 2331
17 0:07 +0.44 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.Nc5 Bc8 35.Re1 Rh4 36.Bxb5 Kg6 37.Bc6 fxe3+ 38.Kxe3 Bg3 39.Re2 Bh2 40.Kd3 Bg1 41.Re8 Rxd4+ (17.579.279) 2331
-----
18 0:10 0.00 30...Qb8 31.Rb1 Rh8 32.Rc1 Qb7 33.Nd2 Qb8 34.Nb3 Rh2 35.Kg1 Rh7 36.Kf2 Rh2 (24.339.592) 2321
18 0:10 0.00 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nb3 Rh2 34.Kg1 Rh7 35.Kf2 Rh2 (24.339.600) 2321
18 0:10 +0.20 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Nd2 Bd7 34.Rc1 g5 35.fxg5 fxg5 36.Nb3 f4 37.e4 dxe4 38.Bxe4 Re6 39.Bd5 Re3 40.Nc5 Bf5 41.Nxa6 Rd3 (24.339.600) 2321
18 0:10 +0.33 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.Nc5 Bc8 35.Re1 a6 36.exf4 Kf7 37.Kf3 Rh4 38.g3 Rh2 39.Rc1 Bb6 40.Rc2 Rh3 41.b4 Kg6 42.Nb3 (24.339.600) 2321
-----
19 0:17 0.00 30...Qb8 31.Rc1 Qb7 32.Nd2 Qb8 33.Nb3 Rh2 34.Kg1 Rh7 35.Kf2 Rh2 (44.816.346) 2503
19 0:17 0.00 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nb3 Rh2 34.Kg1 Rh7 35.Kf2 Rh2 (44.816.437) 2503
19 0:17 +0.25 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Nd2 Bd7 34.Rc1 g5 35.fxg5 fxg5 36.Nb3 f4 37.e4 dxe4 38.Bxe4 Re6 39.Bd5 Rh6 40.Nc5 Bf5 41.Nxa6 g4 42.Nc7 Bd7 (44.816.527) 2503
19 0:17 +0.46 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.Nc5 Bc8 35.Bxb5 fxe3+ 36.Kxe3 Rg6 37.Re1 Bg3 38.Re2 Rg4 39.Bc6 Bh2 40.Bxd5 Bg1+ 41.Kf3 Rxd4 42.Ba2 Rd6 43.b4 Kg6 (44.816.585) 2503
-----
20 0:23 -0.20 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nf3 Rd8 34.a4 bxa4 35.Rc2 Rc8 36.Rxc8 Qxc8 37.Qxd5 Qc6 38.Bc4 Qxd5 39.Bxd5 Bb5 40.Be6 Bd3 41.d5 Be4 42.Nd2 Bd3 (62.006.350) 2624
20 0:23 +0.13 30...Qb8 31.Rc1 Rh8 32.Ne5 fxe5 33.dxe5 d4 34.exd6 Qxd6 35.Qc7 dxe3+ 36.Ke2 Qd5 37.Qe5+ Qxe5 38.fxe5 Kf7 39.Rc7 Ke6 40.Kxe3 Rh2 41.Kf2 Be8 42.Rc5 a6 43.Bc2 f4 (62.006.506) 2624
20 0:23 +0.31 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Nd2 Bd7 34.Nb3 g5 35.Nc5 Bc8 36.fxg5 fxg5 37.Rc1 Rh8 38.Bc2 Rf8 39.Re1 a5 40.Bb3 f4 41.e4 Bxc5 42.dxc5 dxe4 43.Rxe4 (62.006.568) 2624
20 0:23 +0.46 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.Nc5 Bc8 35.Bxb5 fxe3+ 36.Kxe3 Rg6 37.Re1 Bg3 38.Re2 f4+ 39.Kd2 Kh6 40.Re8 Bg4 41.Bd3 Rg7 42.Rd8 Re7 43.Kc3 f3 (62.006.609) 2624
-----
21 0:31 0.00 30...Qb7 31.Nd2 Qb8 32.Nf3 Qb7 (83.902.033) 2641
21 0:31 +0.14 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Nd2 Bd7 34.Nb3 g5 35.Nc5 Bc8 36.fxg5 fxg5 37.Rc1 Rh8 38.Bc2 Kg6 39.Bb3 f4 40.exf4 Bxf4 41.Re1 Rf8 42.Ne6 Rf6 43.Bc2+ Kf7 (83.902.315) 2641
21 0:31 +0.15 30...Qb8 31.Rc1 Rh8 32.Ne5 fxe5 33.dxe5 d4 34.exd6 Qxd6 35.Qc7 dxe3+ 36.Ke2 Qd5 37.Qe5+ Qxe5 38.fxe5 Kf7 39.Rc7 Ke6 40.Kxe3 Rh2 41.Kf2 a5 42.Rc5 Rh4 43.Bxb5 Bxb5 (83.902.373) 2641
21 0:31 +0.43 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.Nc5 Bc8 35.Bxb5 fxe3+ 36.Kxe3 Rg6 37.Re1 Bg3 38.Re2 f4+ 39.Kd2 Kh6 40.Bc6 Rg5 41.Ne6 Bxe6 42.Rxe6 Kg6 43.Ke2 Bh4 (83.902.402) 2641
-----
22 0:44 0.00 30...Qb7 31.Nd2 Qb8 32.Nf3 Rh8 33.Rc1 Rd8 34.Qa6 Re8 35.g3 Rh8 36.Nh4 Rd8 37.Rc2 Qb6 38.Qxb6 axb6 39.Nf3 Ra8 40.Nh4 Rd8 (122.230.983) 2776
22 0:44 0.00 30...Qb8 31.Rc1 Rh7 32.a4 bxa4 33.Qxd5 Qxb2+ 34.Rc2 Qb4 35.Ne5 Be8 36.Nc6 Bxc6 37.Rxc6 Bxf4 38.exf4 Qd2+ 39.Be2 Qxf4+ 40.Qf3 Qxd4+ 41.Qe3 Qh4+ 42.Kf3 Qh5+ 43.Kf2 Qh4+ (122.231.234) 2776
22 0:44 +0.34 30...a6 31.Qb6 Be7 32.Rd1 Rh8 33.Rd2 Qb8 34.Qxa6 Rh1 35.Rc2 Rb1 36.Qa5 Bd6 37.Be2 Ra1 38.Qc3 b4 39.axb4 Qb7 40.b3 Rb1 41.Rc1 Rxc1 42.Qxc1 Bxb4 43.Qh1 Qa8 (122.231.287) 2776
22 0:44 +0.40 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.Nc5 Bc8 35.Bxb5 fxe3+ 36.Kxe3 Rg6 37.Re1 Bg3 38.Re2 f4+ 39.Kd2 Kh6 40.Bc6 Rg5 41.b4 Bg4 42.Re7 Bf2 43.Kc3 Bd1 (122.231.367) 2776
-----
23 1:32 -0.20 30...Qb7 31.Nd2 Qb8 32.Nf3 Rh8 33.Rc1 Rd8 34.g3 Re8 35.Nh4 Qb7 36.Nf3 Rh8 37.Nh4 Kf7 38.Nf3 a6 39.Nh4 Re8 40.Nf3 Kg7 41.Rh1 Qc6 42.Qd2 Be6 (273.926.565) 2947
23 1:32 0.00 30...Qb8 31.Rc1 Rh7 32.a4 bxa4 33.Qxd5 Qxb2+ 34.Rc2 Qb4 35.Ne5 Be8 36.Nc6 Bxc6 37.Rxc6 Bxf4 38.exf4 Qd2+ 39.Be2 Qxf4+ 40.Qf3 Qxd4+ 41.Qe3 Qh4+ 42.Kf3 Qh5+ 43.Kf2 Qh4+ (273.926.698) 2947
23 1:32 +0.27 30...a6 31.Qb6 Qb8 32.Qxa6 Rh8 33.Rc1 Re8 34.g3 Rh8 35.Qa5 Qb7 36.Nh4 Kf7 37.Qd2 b4 38.axb4 Bxb4 39.Qe2 Bd6 40.Ra1 Rb8 41.Ra2 Bb4 42.Kf3 Bf8 43.Ra6 Qxb2 (273.926.901) 2947
23 1:32 +0.46 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.exf4 Rh4 35.Ke3 Kg6 36.g3 Rh3 37.Kf3 Bb6 38.Rc1 Rh2 39.Nc5 Bc6 40.Ne6 Be8 41.Rc2 Rxc2 42.Bxc2 Bf7 43.Nc5 a5 (273.926.982) 2947
-----
24 4:15 -0.09 30...Qb7 31.Nd2 Qb8 32.Nf3 Rh8 33.Rc1 Rd8 34.g3 Re8 35.Nh4 Qb7 36.Nf3 Rh8 37.Nh4 Rb8 38.Qd2 b4 39.a4 Rc8 40.a5 Rxc1 41.Qxc1 Qc7 42.Qxc7 Bxc7 43.a6 Kf7 (869.112.565) 3406
24 4:15 0.00 30...Qb8 31.Rc1 Rh7 32.a4 bxa4 33.Qxd5 Qxb2+ 34.Rc2 Qb4 35.Ne5 Be8 36.Nc6 Bxc6 37.Rxc6 Bxf4 38.exf4 Qd2+ 39.Be2 Rh4 40.Qd7+ Kh6 41.Qd6 Rxf4+ 42.Kg3 Qe3+ 43.Bf3 Rxf3+ (869.112.722) 3406
24 4:15 +0.31 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Nd2 g5 34.Bxf5 b4 35.fxg5 fxg5 36.axb4 Bb5 37.Rc1 Rf6 38.g4 Bd3 39.Nf3 Bxf5 40.gxf5 Rxf5 41.Ke2 g4 42.Rg1 g3 43.Ra1 Bxb4 (869.112.795) 3406
24 4:15 +0.64 30...Qc7 31.Qxc7 Bxc7 32.Nd2 g5 33.Nb3 gxf4 34.exf4 a6 35.Ke3 Rh4 36.Nc5 Bc8 37.Bc2 Rh8 38.Bb3 Re8+ 39.Kf3 Bb6 40.Rh1 Kg6 41.Rh3 a5 42.Bc2 Kf7 43.Bd3 b4 (869.112.860) 3406
-----
25 5:05 -0.12 30...Qb7 31.Rc1 Rh8 32.Nd2 Qb8 33.Nf3 Rd8 34.g3 Rh8 35.Nh4 Qb7 36.Kf3 Re8 37.Kf2 Rb8 38.Kg2 Ra8 39.Kf3 Rh8 40.Kg2 Kf7 41.Kf2 a6 42.Nf3 Rc8 43.Rh1 (1.032.072.504) 3378
25 5:05 0.00 30...Qb8 31.Rc1 Rh7 32.a4 bxa4 33.Qxd5 Qxb2+ 34.Rc2 Qb4 35.Ne5 Be8 36.Nc6 Bxc6 37.Rxc6 Rh1 38.Qxd6 Qe1+ 39.Kf3 Qd1+ 40.Kf2 Qg1+ 41.Kf3 Qd1+ (1.032.072.653) 3378
25 5:05 +0.51 30...a6 31.Qb6 Qc6 32.Qxc6 Bxc6 33.Nd2 g5 34.Bxf5 b4 35.fxg5 fxg5 36.axb4 Bb5 37.Ra1 Bxb4 38.Nf3 Rh8 39.g4 Kf6 40.b3 Bd6 41.Rc1 a5 42.Rb1 Rh3 43.Ra1 Bb4 (1.032.072.720) 3378
25 5:05 +0.61 30...Qc6 31.Qxa7 Be7 32.b4 Rh8 33.Rc1 Qxc1 34.Qxd7 Kf8 35.Bxb5 Qc2+ 36.Be2 Qb3 37.Qc8+ Kg7 38.Qe6 Kf8 39.b5 Qxa3 40.Qxd5 Qd6 41.Qa8+ Kg7 42.Qa7 Qa3 43.Qxa3 Bxa3 (1.032.072.774) 3378

There's nothing wrong with 29...b5, and it's the only way to tempt white into a line that doesn't exchange the rooks with Rh1, because after Rh1 it's just a dead draw. Here, black fights on. Black messes up later.

Most engines were very useless for these positions (you know that when you have to play a move suggested by Critter...), so I had to rely on Komodo to play for an advantage (at it seemed to pay off for a while, until the opponent played into a mate in N position I saw as drawish, and couldn't see white's plan.)

Re: What's up with this endgame?

Posted: Wed Jul 24, 2019 7:30 am
by MikeB
Ovyron wrote:
Wed Jul 24, 2019 7:07 am

There's nothing wrong with 29...b5, and it's the only way to tempt white into a line that doesn't exchange the rooks with Rh1, because after Rh1 it's just a dead draw. Here, black fights on. Black messes up later.

Most engines were very useless for these positions (you know that when you have to play a move suggested by Critter...), so I had to rely on Komodo to play for an advantage (at it seemed to pay off for a while, until the opponent played into a mate in N position I saw as drawish, and couldn't see white's plan.)
I have looked at this some more, and I don't see the loss until you played 53 ...gxf4. That is the only point where I am certain that you are lost. But it's clearly possible that my hardware and software is simply not adequate for this game. I think very few people would have access to computer that can find the winning line if you played something other than gxf4. Well, time for you to start that new unbeaten streak!

Re: What's up with this endgame?

Posted: Wed Jul 24, 2019 7:49 am
by Ovyron
MikeB wrote:
Wed Jul 24, 2019 7:30 am
I have looked at this some more, and I don't see the loss until you played 53 ...gxf4.
You may have missed this post by zullil:
zullil wrote:
Sun Jul 21, 2019 9:36 am


+7.52 40... g5 41. Ke1 Kf8 42. Kd2 Ke7 43. Kc3 Be8 44. Kb4 Kd8 45. Bb5 Bh5 46. Bc6 Bf7 47. Kb5 Kc7 48. g3 Bg8 49. Be8 Kd8 50. Bg6 Kc7 51. Bh5 Be6 52. Kb4 Bc8 53. Be2 Bd7 54. a4 Be8 55. Bb5 Bg6 56. a5 bxa5+ 57. Kxa5 Bh5 58. Bd3 Kc6 59. Bc2 Be2 60. Bxf5 Bf3 61. Be6 Be2 62. Bg8 Bd3 63. Bf7 Be4 64. Be8+ Kc7 65. Kb5 Kd6 66. Bf7 Bd3+ 67. Kb6 gxf4 68. gxf4 Bf1 69. Bg6 Bh3 70. Kb7 Bg4 71. Bd3 Be6 72. Bb5 Bh3 73. Kb6 Bf5 74. Bc6 Be4 75. Be8 Ke7 76. Bb5 Kd6 77. Bc6 Bh1 78. Be8 Be4 79. Kb7 Bd3 80. Bf7 f5 81. Be8 Bf1 82. Kb6 Be2 83. Bc6 Bd1 84. Bb5 Bc2 85. Kb7 Bd1 86. Kc8 (depth 78, 8:57:10)

Looks like White wins. :wink:
White was toast on move 40. I don't think anybody could have drawn the game against zullil at Depth 78 from here. I still don't know if white messed up the win later on. I still don't know what was black's losing move (as it happened before move 40.) I may need to download 6men tablebases to investigate, but I'm not sure it's worth the effort. The lesson for me here was about endgames with same-colored bishops being won for one side (no matter what engines say), this was something new and completely unexpected, specially after seeing endgames where one side has 3 extra pawns and it's a draw, those damn rooks are enough to defend them...
Well, time for you to start that new unbeaten streak!
Unlikely. I have plans to play some more games on the LSS, there some guys play shocking moves stronger than what I've seen 2400 elo ICCF players play, I expect one of then to trounce me at that point. I'll play in the FICGS World Cup just to train for the LSS guys, but I appreciate the sentiment :mrgreen:

Re: What's up with this endgame?

Posted: Wed Jul 24, 2019 9:06 am
by JohnWoe
Quickly running w/ my Sapeli. 100_000 games.

Drawish.
100000 games:

Code: Select all

sapeli -fen "8/3b2k1/1p3pp1/3p1p2/3P1P2/P3P3/5KP1/5B2 b - -" -analyze 100000
...
=
[ Time: 145.47s ]
[ Speed: 687.42 games/s ]
[ Score: 1246 - 1316 - 97438 [0.50] 100000 ]



White is winning.
100000 games:

Code: Select all

sapeli -fen "8/2k5/5pB1/K2p1p2/3P1P2/3b2P1/8/8 b - -" -analyze 100000
...
=
[ Time: 76.17s ]
[ Speed: 1312.92 games/s ]
[ Score: 571 - 195 - 99234 [0.50] 100000 ]