Test Position bm Rxc3

Discussion of anything and everything relating to chess playing software and machines.

Moderators: hgm, Harvey Williamson, bob

Forum rules
This textbox is used to restore diagrams posted with the [d] tag before the upgrade.
User avatar
MikeGL
Posts: 873
Joined: Thu Sep 01, 2011 12:49 pm

Test Position bm Rxc3

Post by MikeGL » Tue May 07, 2019 4:36 am

This position arised after SF10 played 27.Kf2 and the winning response for black(Lc0) is [bm 27...Rxc3!]
[d]1kr1b3/pr6/3pq3/n2p1p2/3P1Pp1/P1N1P1Pp/RP1NQK1P/4R3 b - - 3 27
I tried to analyze where SF10 went wrong after Rxc3, but looks like it made excellent defense but is really lost after exchange sacrifice of black.
Positional dominance of black as white rooks are tamed by minor pieces. N stronger than R on this setup, and bad bishop nicely activated.
Similar to one of those brilliancy games of top GMs. This positional exchange sacrifice is deep.

Complete game:
I told my wife that a husband is like a fine wine; he gets better with age. The next day, she locked me in the cellar.

User avatar
AdminX
Posts: 5115
Joined: Mon Mar 13, 2006 1:34 pm
Location: Acworth, GA
Contact:

Re: Test Position bm Rxc3

Post by AdminX » Tue May 07, 2019 8:42 am

Leela (JH.T6.532) does not care for 35. Qc1

Code: Select all

Stockfish 10 181129 - Lc0 0.21.1 N:42100 0-1
8/1rk5/3pq3/p2p1p2/3P1Pp1/P1PbP1Pp/Rn1N3P/3QR1K1 w - - 0 1

Analysis by Lc0 v0.22.0-Dev-JHT:

1. =/+ (-0.53): 35.Qa1 Na4 36.e4 dxe4 37.c4 Kb8 38.d5 Qc8 39.Qd4 Ka8 40.Kf2 Nc5 41.Ke3 Qb8 42.Rc1 Qa7 43.Qh8+ Rb8 44.Qd4 a4 45.Rd1 Qb6 46.Rc1 Rb7 47.Rc3 Ka7 48.Rc1 Ka6 49.Rc3 Rb8 50.Rc1 Qa7 51.Rc3 Qe7 52.Rc1 
2. -/+ (-0.74): 35.Qc1 Na4 36.Qd1 Qe8 37.Qc1 Qc6 38.Qa1 Kb8 39.Rc1 Ka7 40.Kf2 Rb6 41.Kg1 Ka6 42.Kf2 Rb8 43.Kg1 Qe8 
Black is slightly better
"Good decisions come from experience, and experience comes from bad decisions."
__________________________________________________________________
Ted Summers

User avatar
MikeGL
Posts: 873
Joined: Thu Sep 01, 2011 12:49 pm

Re: Test Position bm Rxc3

Post by MikeGL » Tue May 07, 2019 10:14 am

AdminX wrote:
Tue May 07, 2019 8:42 am
Leela (JH.T6.532) does not care for 35. Qc1

Code: Select all

Stockfish 10 181129 - Lc0 0.21.1 N:42100 0-1
8/1rk5/3pq3/p2p1p2/3P1Pp1/P1PbP1Pp/Rn1N3P/3QR1K1 w - - 0 1

Analysis by Lc0 v0.22.0-Dev-JHT:

1. =/+ (-0.53): 35.Qa1 Na4 36.e4 dxe4 37.c4 Kb8 38.d5 Qc8 39.Qd4 Ka8 40.Kf2 Nc5 41.Ke3 Qb8 42.Rc1 Qa7 43.Qh8+ Rb8 44.Qd4 a4 45.Rd1 Qb6 46.Rc1 Rb7 47.Rc3 Ka7 48.Rc1 Ka6 49.Rc3 Rb8 50.Rc1 Qa7 51.Rc3 Qe7 52.Rc1 
2. -/+ (-0.74): 35.Qc1 Na4 36.Qd1 Qe8 37.Qc1 Qc6 38.Qa1 Kb8 39.Rc1 Ka7 40.Kf2 Rb6 41.Kg1 Ka6 42.Kf2 Rb8 43.Kg1 Qe8 
Black is slightly better
Thanks for the line. I checked and analyzed it using engine and it seems black will still have a strong winning position after 37.c4 then not Kb8 but 37...Kb6! and win for black looks inevitable.
Funny to see until at the end of your first line, both white rooks were still unable to challenge/occupy the only open b-file because of the bishop controlling b1 square.
I told my wife that a husband is like a fine wine; he gets better with age. The next day, she locked me in the cellar.

chrisw
Posts: 1866
Joined: Tue Apr 03, 2012 2:28 pm

Re: Test Position bm Rxc3

Post by chrisw » Tue May 07, 2019 11:17 am

30 Ra1 looks better, after Rc2 it seems black just gets a huge grip on the position

chrisw
Posts: 1866
Joined: Tue Apr 03, 2012 2:28 pm

Re: Test Position bm Rxc3

Post by chrisw » Tue May 07, 2019 1:18 pm

Yup, 30 Ra1 and white is okay, but no computer will see it. Funny position.
Last edited by chrisw on Tue May 07, 2019 1:44 pm, edited 1 time in total.

jp
Posts: 702
Joined: Mon Apr 23, 2018 5:54 am

Re: Test Position bm Rxc3

Post by jp » Tue May 07, 2019 1:39 pm

MikeGL wrote:
Tue May 07, 2019 4:36 am
This position arised after SF10 played 27.Kf2 and the winning response for black(Lc0) is [bm 27...Rxc3!]
What roughly were the nodes per move for SF10 & Lc0 (in the game)?

User avatar
MikeGL
Posts: 873
Joined: Thu Sep 01, 2011 12:49 pm

Re: Test Position bm Rxc3

Post by MikeGL » Tue May 07, 2019 1:58 pm

jp wrote:
Tue May 07, 2019 1:39 pm
MikeGL wrote:
Tue May 07, 2019 4:36 am
This position arised after SF10 played 27.Kf2 and the winning response for black(Lc0) is [bm 27...Rxc3!]
What roughly were the nodes per move for SF10 & Lc0 (in the game)?
Sorry, forgot to mention the credit line.
Credit goes to Stefan Pohl, that was not my Lc0 testing,

I was just analyzing these types of games. Since I feel these are almost perfect games, just so I get a positional feel on my real OTB games against strong opposition.

Here's the source of the game and his hardware setup:
Stefan Pohl
Hardware details of Stefan for testing these engines
https://www.sp-cc.de/lc0-testing.htm

//////////////////////// copied from the above link //////////////////////
Hardware: i7-8750H (Hexacore) Notebook with RTX 2060 GPU, Windows 10 64bit, 16GB RAM

CPU-Speed: Stockfish with 97% CPU-Speed (to switch off the Intel Turbo Boost): 7.5 MN/s in starting-position, running on 11 threads.

GPU (used by LC Zero): Nvidia RTX 2060 (6GB). LC Zero calculates around 11500 n/s in the starting position (I used the MSI-Afterburner-tool to reduce the speed of the RTX-Card as far as possible) (measured with "go infinte") with Netsize 20x256, which means a Leela-Ratio (what is Leela Ratio? look here) of 1.3.The Leela-Ratio-value of AlphaZero (used a 20x256 net, too) in the match vs. Stockfish 8 was 1.0 - so 1.3 is a high value, but acceptable.

Hash: 1 GB for AB-engines and 1.000.000 size of NNCache for Leela
GUI: LittleBlitzerGUI, draw at 160 moves, resign at a -700 cp evaluation.
Tablebases: none
Openings: 4 SuperGM-moves. Download my 4-moves opening-sets and books here
Large Memory Pages: Off
Ponder: Off
Thinking time: 150'' (2.5 minutes) +1500ms (average game-duration: 8-9 minutes)
/////////////////////


Source PGN of this game:
https://www.sp-cc.de/files/nn_engine_games.zip
4,054th game entry from that PGN
I told my wife that a husband is like a fine wine; he gets better with age. The next day, she locked me in the cellar.

User avatar
MikeGL
Posts: 873
Joined: Thu Sep 01, 2011 12:49 pm

Re: Test Position bm Rxc3

Post by MikeGL » Tue May 07, 2019 2:53 pm

chrisw wrote:
Tue May 07, 2019 11:17 am
30 Ra1 looks better, after Rc2 it seems black just gets a huge grip on the position
I tried to run analysis with MultiPV and just ends up with B vs R endgame, but a pawn up and slightly better for black.
Better space and possible K activity compared to K of white, but might require deeper analysis.

I told my wife that a husband is like a fine wine; he gets better with age. The next day, she locked me in the cellar.

chrisw
Posts: 1866
Joined: Tue Apr 03, 2012 2:28 pm

Re: Test Position bm Rxc3

Post by chrisw » Tue May 07, 2019 3:39 pm

MikeGL wrote:
Tue May 07, 2019 2:53 pm
chrisw wrote:
Tue May 07, 2019 11:17 am
30 Ra1 looks better, after Rc2 it seems black just gets a huge grip on the position
I tried to run analysis with MultiPV and just ends up with B vs R endgame, but a pawn up and slightly better for black.
Better space and possible K activity compared to K of white, but might require deeper analysis.

e4 is absolute key move, cutting blacks ability to pivot on that square.

30. Ra1 Bd3 31. e4 dxe4 32. Qa4 Nb3 33. Ra2 is better than the above Rad1 (which threatens nothing and allows black to improve his position)

after 33. Ra2 Nc1 is just drawing, Nc5 also a draw. NxN is draw, some positions are like your line, but a vital tempo ahead (various defences, including Ke3 and counter exchange sac, the tempo is important here)
a6 would be an attempt to keep pieces on the board, but it isn't enough and the position holds, I think.

Key was e4, it gave the king a blockade square on e3, prevented the mating threat lines with Qe4 and gained just enough time. Therefore draw, not decisive black win by strangulation.

peter
Posts: 1760
Joined: Sat Feb 16, 2008 6:38 am
Full name: Peter Martan

Re: Test Position bm Rxc3

Post by peter » Tue May 07, 2019 4:22 pm

Hi Mike!
Thanks for the position!
MikeGL wrote:
Tue May 07, 2019 10:14 am
AdminX wrote:
Tue May 07, 2019 8:42 am
Leela (JH.T6.532) does not care for 35. Qc1

Code: Select all

Stockfish 10 181129 - Lc0 0.21.1 N:42100 0-1
8/1rk5/3pq3/p2p1p2/3P1Pp1/P1PbP1Pp/Rn1N3P/3QR1K1 w - - 0 1

Analysis by Lc0 v0.22.0-Dev-JHT:

1. =/+ (-0.53): 35.Qa1 Na4 36.e4 dxe4 37.c4 Kb8 38.d5 Qc8 39.Qd4 Ka8 40.Kf2 Nc5 41.Ke3 Qb8 42.Rc1 Qa7 43.Qh8+ Rb8 44.Qd4 a4 45.Rd1 Qb6 46.Rc1 Rb7 47.Rc3 Ka7 48.Rc1 Ka6 49.Rc3 Rb8 50.Rc1 Qa7 51.Rc3 Qe7 52.Rc1 
2. -/+ (-0.74): 35.Qc1 Na4 36.Qd1 Qe8 37.Qc1 Qc6 38.Qa1 Kb8 39.Rc1 Ka7 40.Kf2 Rb6 41.Kg1 Ka6 42.Kf2 Rb8 43.Kg1 Qe8 
Black is slightly better
Thanks for the line. I checked and analyzed it using engine and it seems black will still have a strong winning position after 37.c4 then not Kb8 but 37...Kb6! and win for black looks inevitable.
How about 36.Nf1 instead of e4?
After deviation 31.Qa1 Na4 32.Nf1 Fish doesn't see any progress for Black anymore.
(
1. Qb3 Nc6 2. Bg5 f6 3. Bd2 Qd7 4. Nc3 O-O-O 5. Na4 Bd6 6. e3 Nge7 7. a3 h5 8.
Bb4 Kb8 9. Bxd6 cxd6 10. Nc3 h4 11. Nd2 Qe6 12. Ba6 Na5 13. Qb5 Rd7 14. Qxa5
bxa6 15. Qxa6 h3 16. g3 Rb7 17. Ra2 g5 18. O-O Rc8 19. Re1 Bg6 20. Qf1 Nc6 21.
Raa1 Ka8 22. Ra2 Kb8 23. f3 Na5 24. Qf2 f5 25. f4 g4 26. Qe2 Be8

27. Kf2 Rxc3 28. bxc3 Bb5 29. Qd1 Bc4 30. Rc2 Bd3 31. Ra2 Nc4 32. Qa1 Kc7 33. Kg1 a5 34. Qd1
Nb2

35. Qa1 Na4 36. Nf1
)


Analysis by CF OPT 180419 x64 POP NUMA:

36...De4 37.Tf2 Sb6 38.a4 Sc4 39.Sd2 De8 40.e4 Lxe4 41.Tef1 Tb6 42.Tc1 Dc6 43.Te1 Kd7 44.Tc1 Ke7 45.Te1
= (0.00) Tiefe: 54/34 00:06:21 8123MN

After some Forward- Backward with 24 threads of 12x3GHz CPU, 32G hash
Last edited by peter on Tue May 07, 2019 4:36 pm, edited 2 times in total.
Peter.

Post Reply