Possiblity of an cooked study

Nordlandia · Post by **Nordlandia** » Fri Mar 15, 2019 4:06 pm

It is possible that this study is unsound.

Usually RN vs RBN is a tablebase win. There are some chances of that RNP vs RBN is a tablebase win. I'd suspect analysing that endgame with 7-piece syzygy can give us better answer than analysing it with 6-piece syzygy.

J. Rusinek | 1st price L' Italia Scacchistica 1976
[d]8/8/1r5k/8/7K/3RP3/2b1n3/1N6 w - - 0 0

[pgn][Event "?"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "New game"] [Black "?"] [Result "*"] [SetUp "1"] [FEN "8/8/1r5k/8/7K/3RP3/2b1n3/1N6 w - - 0 0"] [PlyCount "7"] {[#]} 1. Rd2 Rb4+ 2. Kh3 Bf5+ (2... Ng1+ $11) 3. Kg2 Rg4+ 4. Kf2 * [/pgn]

Longest RN v RBN endgame - 2N1nB2/8/4k3/8/6r1/7R/3K4/8 b - - | White mates in 231.

peter · Post by **peter** » Sat Mar 16, 2019 1:03 am

Nordlandia wrote: ↑Fri Mar 15, 2019 4:06 pm I'd suspect analysing that endgame with 7-piece syzygy can give us better answer than analysing it with 6-piece syzygy.

I don't think so, Jon, if you cannot find a way to reach 7men position at all without losing instead of winning. Author's theme is a fortress, if you want to refute it, you simply have to give a line with any progress at all, with our without tbs. Or you just have to get 50- moves boundary into horizon and then keep it in hash backwarding. Of course that's a long way, so you won't make it fully, but probably not much better with 7men Syzygys instead of 6.

8/8/1r5k/8/7K/3RP3/2b1n3/1N6 w - - 0 1

Analysis by CF EXT 120319 x64 POP NUMA:

1.Rd2 Rb4+ 2.Kh3 Bf5+ 3.Kg2 Rg4+ 4.Kf2 Ng1 5.Rd6+ Kg7 6.Nd2 Nh3+ 7.Kf3 Rg1 8.Rb6 Bg6 9.e4 Bh5+ 10.Ke3 Re1+ 11.Kd4 Nf2 12.Ke5 Bg6 13.Rb7+ Kh6 14.Rb6 Re2 15.Rd6 Nh3 16.Rd5 Bh7 17.Rd3 Ng5 18.Kf4 Rf2+ 19.Ke3 Rf7 20.Rd5 Rf8 21.Rb5 Bg6 22.Rb6 Re8 23.Ra6 Rc8 24.Kf4 Rf8+ 25.Ke3 Re8 26.Rc6 Rb8 27.Kf4 Ra8 28.Kg4 Rf8 29.Ra6
-/+ (-0.85) Depth: 50/56 00:02:04 2977MN, tb=69724990

Black will try to win of course 50 moves long after last pawn-move.

So positions like this one

[d]8/5k1b/3Rn3/4KN2/r3P3/8/8/8 b - - 0 52

won't arise before at least 50 moves and there Black can exchange the Bishop against the Knight reaching a remis- 7men position or go on shuffling.

http://www.yacpdb.org/#search/ODgxcjVrO ... MS8xLzA=/1

Nordlandia · Post by **Nordlandia** » Sat Mar 16, 2019 10:24 am

Peter: not all EG studies enforce 50-move rule. This study can be an exception. The likelihood for black to winning is minimally.

Nordlandia · Post by **Nordlandia** » Sat Mar 16, 2019 12:16 pm

Peter: here 7-piece syzygy will definitely give better answer than 6-piece syzygy.

No 19384 | V. Kirillov & E. Kudelich | Honourable mention | EG October 2013 Supplement, page 398

[d]1K6/8/2P3P1/1R6/8/5n2/4rrPk/6b1 w - - 0 1

Possible cook

Winning 8-man EGTB position.

http://www.viewchess.com/cbreader/2017/ ... 23453.html

peter · Post by **peter** » Sat Mar 16, 2019 12:46 pm

Nordlandia wrote: ↑Sat Mar 16, 2019 10:24 am Peter: not all EG studies enforce 50-move rule.

Of course not, Jon, just the fortresses among them often do so

Nordlandia · Post by **Nordlandia** » Sat Mar 16, 2019 2:03 pm

Peter: this is an classic when the 50-move rule saves white.

8/1p6/1p6/kPp2P1K/2P5/N1Pp4/q2P4/1N6 w - - 0 1

[pgn][Event "Internet"] [Site "?"] [Date "1991.??.??"] [Round "?"] [White "Elkies=N"] [Black "(=3002.54h5a5)"] [Result "1/2-1/2"] [SetUp "1"] [FEN "8/1p6/1p6/kPp2P1K/2P5/N1Pp4/q2P4/1N6 w - - 0 1"] 1. f6 Qb3 2. f7 Qd1 3. Kh6 Qf3 4. Kg7 Qg4 5. Kh8 Qf5 6. Kg7 Qg5 7. Kh7 Qf6 8. Kg8 Qg6 9. Kf8 Ka4 10. Ke7 Qg7 11. Ke8 Qe5 12. Kd7 Qf6 13. Ke8 Qe6 14. Kf8 Kb3 15. Kg7 Qe7 16. Kg8 Qg5 17. Kh8 Qf6 18. Kg8 Qg6 19. Kf8 Kb2 20. Ke7 Qg7 21. Ke8 Qe5 22. Kd8 Qf6 23. Ke8 Qe6 24. Kf8 Kc1 25. Kg7 Qe7 26. Kg8 Qg5 27. Kh8 Qh6 28. Kg8 Qg6 29. Kf8 Kd1 30. Ke7 Qg7 31. Ke8 Qe5 32. Kd7 Qf6 33. Ke8 Qe6 34. Kf8 Ke2 35. Kg7 Qe7 36. Kg8 Qg5 37. Kh8 Qf6 38. Kg8 Qg6 39. Kf8 Kf3 40. Ke7 Qg7 41. Ke8 Qe5 42. Kd7 Qf6 43. Ke8 Qe6 44. Kf8 Kf4 45. Kg7 Qe7 46. Kg8 Qg5 47. Kh7 Qf6 48. Kg8 Qg6 49. Kf8 Ke5 50. Ke7 Qg7 51. Ke8 Ke6 52. Kd8 1/2-1/2[/pgn]

peter · Post by **peter** » Sat Mar 16, 2019 4:42 pm

Nordlandia wrote: ↑Sat Mar 16, 2019 12:16 pm No 19384 | V. Kirillov & E. Kudelich | Honourable mention | EG October 2013 Supplement, page 398

[d]1K6/8/2P3P1/1R6/8/5n2/4rrPk/6b1 w - - 0 1

Possible cook

Winning 8-man EGTB position.

http://www.viewchess.com/cbreader/2017/ ... 23453.html

You brought that here not long ago.

viewtopic.php?p=790544#p790544

Thanks for the names of the authors now, but the link to the cbreader doesn't deal with this one.

Paloma · Post by **Paloma** » Sat Mar 16, 2019 6:35 pm

> You brought that here not long ago.

Short-term memory

peter · Post by **peter** » Sat Mar 16, 2019 8:14 pm

Paloma wrote: ↑Sat Mar 16, 2019 6:35 pm > You brought that here not long ago.

Short-term memory

Not quite or not only, rather database- storage too

peter · Post by **peter** » Sat Mar 16, 2019 8:50 pm

Nordlandia wrote: ↑Sat Mar 16, 2019 12:16 pm [d]1K6/8/2P3P1/1R6/8/5n2/4rrPk/6b1 w - - 0 1

Having made a new Backward of the lines, I had stored in February already, I got an even better output now:

1K6/8/2P3P1/1R6/8/5n2/4rrPk/6b1 w - - 0 1

Analysis by CF EXT 120319 x64 POP NUMA:

1.c7 Rxg2 2.c8Q Rxg6 3.Rh5+ Kg3 4.Qh3+ Kf2 5.Rf5 Rg3 6.Qh6 Kg2 7.Qc6 Rg8+ 8.Kb7 Re7+ 9.Ka6 Re3 10.Rc5 Rg4 11.Rc4 Rg7 12.Kb5 Bf2 13.Rc2 Rg4 14.Rc4 Rg5+ 15.Ka4 Ree5 16.Rc3 Be3 17.Rd3 Rg4+ 18.Ka3 Bc5+ 19.Ka2 Re2+ 20.Kb3 Be3 21.Ka3 Kf2 22.Qc7 Re4 23.Qc8 Re7 24.Rc3 Ra7+ 25.Kb3 Raa2 26.Kc4 Ra4+ 27.Kb3 Rf4 28.Ka3 Nd4 29.Rc5 Rf3 30.Kb4 Rb2+ 31.Kc4 Rc2+ 32.Kd5 Rd2 33.Qh8 Ne6+ 34.Kc6 Nxc5 35.Qh2+ Kf1 36.Qh1+ Ke2 37.Kb5
-+ (-52.96) Depth: 58/72 00:05:25 8219MN, tb=215013784

Still with 6men Syzygys only

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