Queen and pawn endgame

[Rodolfo Leoni]

I downloaded FinalGen and set up the position, but after a while it said "The position is too complex. Set up a simpler position and try again."

Nevertheless, thanks a lot for the idea! FinalGen seems like a very useful tool.

FinalGen after 10 hours of generation time: Either win or draw.

I've given up on FinalGen myself.

As for me, I'd need to get rid of some files in the HD...

But I'm happy enough. Stockfish PA GTB already learned Qxf3 is a blunder, and without GM Gurevich help.... It plays until Qxb2 about instantly. I'll let it run tonight....

[pgn][Event "Computer chess game"]
[Site "UTENTE-PC"]
[Date "2017.07.23"]
[Round "?"]
[White ""]
[Black ""]
[Result "*"]
[BlackElo "2000"]
[Time "19:51:32"]
[WhiteElo "2000"]
[SetUp "1"]
[FEN "6k1/1p3pp1/p6p/7P/3Q2P1/5P2/PPPK4/5q2 b - - 0 1"]
[Termination "unterminated"]
[PlyCount "21"]
[WhiteType "human"]
[BlackType "human"]

1...Qg2+ 2.Ke3 Qg1+ 3.Ke4 Qe1+ 4.Qe3 Qb4+ 5.Kd3 Qb5+ 6.Kd2 Qxb2
7.Qe8+ Kh7 8.Qxf7 Qd4+ 9.Ke2 Qe5+ 10.Kd3 Qd6+ 11.Kc3 Qe5+ *

[/pgn]

This is the sequence of "best moves" generated by Stockfish PA GTB. Score didn't get properly propagated, tough. It scores 1. ..Qg2 -0.41 and 11.Qe5 about 0.90. After a dozen of games, all (26) ended with a draw, except one when AsmFishW played 5. ..Qxb2 (instead of Qb5+). In that game, W won.

After that sequence, tree expands a lot and it's not easy to evaluate. White has no progresses, anyway.

I didn't look at games... No time to do. I hope that could be a clue.

Bye!

Rodolfo

[Rodolfo Leoni]

Even the high evaluation for White that I see after Qb2+ might just be an illusion. For example, in its line following Qb2+, asmFish has this position:
[d] 8/1K4pk/2P1q2p/8/1Q6/8/8/8 b - - 11 93
Searching this position to depth 93, asmFish shows 6.29 but no further progress. If this position is actually 0.00, then even Qb2+ might be OK to hold a draw for Black.

Maybe someone with access to 7-man tables can help here, at least with this one position!

7-men says White mates in 49.

Interesting! Thanks.

I tried FinalGen shortly. It would need 7 hours (with my slow pc) and 40 GBs to generate the related TBs. In this case, thanks to Ignacio, we already have an answer. But for similar positions it looks a great tool. Indeed!

Thanks to Evert for the hint.

[Maxwell86]

But I'm happy enough. Stockfish PA GTB already learned Qxf3 is a blunder, and without GM Gurevich help.... It plays until Qxb2 about instantly. I'll let it run tonight....

So, your engine quickly sees that 35....Qxf3 loses (without the help of Gurevich! ). At which depth? Actually, what is "Stockfish PA GTB"?

[Maxwell86]

If I understand correctly, so far we have
*) 20 games (1 minute) of Lyudmil where white scored 80%.
*) 26 games (fixed depth 30) of Rodolfo where black drew all the games.
*) After 44.Kd3 Qd6+ 45.Kc3 Qe5+ 46.Kc4 Qb5+ 47.Kd4 Qb6+ 48.Ke5, 48....Qb2+ somehow loses, but 48....Qc5+ is probably(?) a draw.

I'm quite impressed how deep the analysis has gone. And this was only my first post
Louis, Lyudmil and Rodolfo, thanks a lot for the effort!

[zullil]

If I understand correctly, so far we have
*) 20 games (1 minute) of Lyudmil where white scored 80%.
*) 26 games (fixed depth 30) of Rodolfo where black drew all the games.
*) After 44.Kd3 Qd6+ 45.Kc3 Qe5+ 46.Kc4 Qb5+ 47.Kd4 Qb6+ 48.Ke5, 48....Qb2+ somehow loses, but 48....Qc5+ is probably(?) a draw.

I'm quite impressed how deep the analysis has gone. And this was only my first post
Louis, Lyudmil and Rodolfo, thanks a lot for the effort!

You're welcome! I hope you continue to post here.

[Guenther]

But I'm happy enough. Stockfish PA GTB already learned Qxf3 is a blunder, and without GM Gurevich help.... It plays until Qxb2 about instantly. I'll let it run tonight....

So, your engine quickly sees that 35....Qxf3 loses (without the help of Gurevich! :-D). At which depth? Actually, what is "Stockfish PA GTB"?

Stockfish PA GTB is an old version of Stockfish (2013/11) with a Persistent hash feature, especially for analysis that was maintained by Jeremy Bernstein. It is still available for download.
It was suggested to Rodolfos' (after a long hiatus) request for a better analysis program in this thread:

http://talkchess.com/forum/viewtopic.php?t=64517

download link for SF PA GTB here:
http://www.open-chess.org/viewtopic.php?f=7&t=2663

Note that also as an offspring of that request Daniel Jose made a special
version of Andscacs and an SF with basic PH, but I haven't tested both yet.
I leave it to Rodolfo to tell about those ;-)

Guenther

[Lyudmil Tsvetkov]

If I understand correctly, so far we have
*) 20 games (1 minute) of Lyudmil where white scored 80%.
*) 26 games (fixed depth 30) of Rodolfo where black drew all the games.
*) After 44.Kd3 Qd6+ 45.Kc3 Qe5+ 46.Kc4 Qb5+ 47.Kd4 Qb6+ 48.Ke5, 48....Qb2+ somehow loses, but 48....Qc5+ is probably(?) a draw.

I'm quite impressed how deep the analysis has gone. And this was only my first post
Louis, Lyudmil and Rodolfo, thanks a lot for the effort!

hi Bart.

thanks for being with us again.

fixed depth makes no sense, Rodolpho does not know what he is doing: limiting SF search, especially in the endgame, where SF usually reaches 70-80 plies, is completely irrelevant.

there is something wrong about his analysis too.

[d]8/1p3Qpk/pq5p/4K2P/6P1/5P2/P1P5/8 b - - 7 4

well, we have this position now.

if Qb2 loses, Qe3 loses too, and we do'n't know what Qc5 and Qb4 are(I checked the Qc5 line briefly and white seems to gradually increase its score), then, by simple arithmetics, white is winning half, and has the chance to win another 50% of the remaining half, so I would not say the position is very drawish.

of course, it might be still a draw with perfect play, but all we can do is approximate and evaluate different lines, as we don't know what perfect play is.

[Lyudmil Tsvetkov]

I downloaded FinalGen and set up the position, but after a while it said "The position is too complex. Set up a simpler position and try again."

Nevertheless, thanks a lot for the idea! FinalGen seems like a very useful tool.

FinalGen after 10 hours of generation time: Either win or draw.

I've given up on FinalGen myself.

As for me, I'd need to get rid of some files in the HD...

But I'm happy enough. Stockfish PA GTB already learned Qxf3 is a blunder, and without GM Gurevich help.... It plays until Qxb2 about instantly. I'll let it run tonight....

[pgn][Event "Computer chess game"]
[Site "UTENTE-PC"]
[Date "2017.07.23"]
[Round "?"]
[White ""]
[Black ""]
[Result "*"]
[BlackElo "2000"]
[Time "19:51:32"]
[WhiteElo "2000"]
[SetUp "1"]
[FEN "6k1/1p3pp1/p6p/7P/3Q2P1/5P2/PPPK4/5q2 b - - 0 1"]
[Termination "unterminated"]
[PlyCount "21"]
[WhiteType "human"]
[BlackType "human"]

1...Qg2+ 2.Ke3 Qg1+ 3.Ke4 Qe1+ 4.Qe3 Qb4+ 5.Kd3 Qb5+ 6.Kd2 Qxb2
7.Qe8+ Kh7 8.Qxf7 Qd4+ 9.Ke2 Qe5+ 10.Kd3 Qd6+ 11.Kc3 Qe5+ *

[/pgn]

This is the sequence of "best moves" generated by Stockfish PA GTB. Score didn't get properly propagated, tough. It scores 1. ..Qg2 -0.41 and 11.Qe5 about 0.90. After a dozen of games, all (26) ended with a draw, except one when AsmFishW played 5. ..Qxb2 (instead of Qb5+). In that game, W won.

After that sequence, tree expands a lot and it's not easy to evaluate. White has no progresses, anyway.

I didn't look at games... No time to do. I hope that could be a clue.

Bye!

Rodolfo

how can you possibly limit SF search in the endgame to 30 plies(ridiculous), when SF usually reaches 70 or so plies in such simple endgames?

no one would accept such stats.

[Lyudmil Tsvetkov]

But I'm happy enough. Stockfish PA GTB already learned Qxf3 is a blunder, and without GM Gurevich help.... It plays until Qxb2 about instantly. I'll let it run tonight....

So, your engine quickly sees that 35....Qxf3 loses (without the help of Gurevich! ). At which depth? Actually, what is "Stockfish PA GTB"?

Stockfish PA GTB is an old version of Stockfish (2013/11) with a Persistent hash feature, especially for analysis that was maintained by Jeremy Bernstein. It is still available for download.
It was suggested to Rodolfos' (after a long hiatus) request for a better analysis program in this thread:

http://talkchess.com/forum/viewtopic.php?t=64517

download link for SF PA GTB here:
http://www.open-chess.org/viewtopic.php?f=7&t=2663

Note that also as an offspring of that request Daniel Jose made a special
version of Andscacs and an SF with basic PH, but I haven't tested both yet.
I leave it to Rodolfo to tell about those

Guenther

excellent, so we now also use outdated software...

[Guenther]

But I'm happy enough. Stockfish PA GTB already learned Qxf3 is a blunder, and without GM Gurevich help.... It plays until Qxb2 about instantly. I'll let it run tonight....

So, your engine quickly sees that 35....Qxf3 loses (without the help of Gurevich! :-D). At which depth? Actually, what is "Stockfish PA GTB"?

Stockfish PA GTB is an old version of Stockfish (2013/11) with a Persistent hash feature, especially for analysis that was maintained by Jeremy Bernstein. It is still available for download.
It was suggested to Rodolfos' (after a long hiatus) request for a better analysis program in this thread:

http://talkchess.com/forum/viewtopic.php?t=64517

download link for SF PA GTB here:
http://www.open-chess.org/viewtopic.php?f=7&t=2663

Note that also as an offspring of that request Daniel Jose made a special
version of Andscacs and an SF with basic PH, but I haven't tested both yet.
I leave it to Rodolfo to tell about those ;-)

Guenther

excellent, so we now also use outdated software...

You are worse than Rolf ever was - stay out if you have no clue what we are talking about, or even better create your own forum...