Positional Test Position

[Uri Blass]

I agree, it is a difficult test position that can distinguish stockfish from komodo currently. IMHO more tasty would have been to skip the forced move sequence and start from here
[d]r1b3k1/ppp2pp1/3p3p/8/2P4N/P5P1/1P2qPB1/R1B2RK1 w - - 1 18

White will loose a pawn soon and then the formal material balance is even.
Stockfish believes the position is balanced, komodo believes white is to be preferred and shows a convincing pv, leading to this position:

[d]r6k/p1p2Bp1/1p5p/1bp1N3/q7/P3B1P1/3R1P2/R5K1 b - - 1 26
Suddenly both engines recommend 26..g5?(?) as if that would be completely normal.
They then follow up with 27.f4! and black is busted soon. However there must be better attempts to defend, e.g. 26..Be8!? and no mate attack is there.

So we can safely conclude that unbalanced positions are difficult.

Another modified Stockfish at depth 40, 26... g5 is still there but 26... Be8 has just suffered a Fail Low throwing it out of the best four, and out of nowhere a new best move appears, 26... a6 This is all without any change to King safety, but you would think the depth can compensate it a bit.


[d]r6k/p1p2Bp1/1p5p/1bp1N3/q7/P3B1P1/3R1P2/R5K1 b - -

Engine: Sf20140810_022 MOD MP (Q6700, 32 bit 4 threads, 512 MB)
by Tord Romstad, Marco Costalba and Joona

40 513:17 -0.79 1...a6 2.Bg6 Kg8 3.Bc2 Qa5 4.Rad1 Re8
5.Bg6 Rxe5 6.Rd8+ Be8 7.Bf4 Re6
8.Rxe8+ Rxe8 9.Bxe8 Kf8 10.Bg6 (97.998.983.449) 3182

40 513:17 -0.84 1...g5 2.f4 gxf4 3.gxf4 Rf8 4.Kf2 Be8
5.Rd8 Kh7 6.Bc4 Qc2+ 7.Kg3 Qc3
8.Bd3+ Kg7 9.Rg1 Kf6 10.Kh2 h5 11.a4 Rh8
12.Rc8 Qb4 13.Rxe8 Rxe8 14.Rg6+ Ke7 (97.998.983.449) 3182

40 513:17 -0.95 1...Kh7 2.Bg6+ Kg8 3.Bc2 Qa5 4.Rad1 Re8
5.Bg6 Rxe5 6.Rd8+ Be8 7.Bxe8 Kh7
8.a4 Qc3 9.Bb5 Kg6 10.Kg2 Qb4 11.Bd2 Qb3
12.Bf4 Re7 13.R8d7 Rxd7 14.Rxd7 a6 (97.998.983.449) 3182

40 513:17 -1.00 1...Qe4 2.Bf4 Qf5 3.Bg6 Qf6 4.Rad1 Kg8
5.Bc2 Rc8 6.Bb3+ Kh7 7.a4 Be8 8.Nd7 Qe7
9.Rd3 c4 10.Bxc4 Bh5 11.Rc1 Bg6
12.Rdd1 Bf5 13.Ne5 c5 14.Nf7 Bg4 (97.998.983.449) 3182

I get worse score than -1.00 at depth 39 with newer version after running stockfish in console mode for many hours(single thread with the default hash tables and probably I could get this depth faster with a bigger hash)

The best move that my stockfish found Rb8 does not appear in your first 4 moves(I believe that every move lose)

I do not plan to wait to get depth 40.

info depth 39 seldepth 79 score cp -101 nodes 72883033077 nps 1078113 time 67602
398 multipv 1 pv a8b8 f7g6 h8g8 g6c2 a4a5 a1d1 b8e8 c2g6 e8e5 d2d8 b5e8 e3d2 a5a
4 d1e1 e5e1 d2e1 g8f8 e1c3 f8e7 d8e8 e7d7 e8e3 a4g4 g6e8 d7d6 c3e5 d6d5 e5c7 g7g
5 c7e5 g4f5 e5g7 d5d6 e8h5 g5g4

[BeyondCritics]

This analysis contributes 32.Bd2! which is even more convincing.
With hindsight 24.Kh8? appears to be an error in critical position, loosing a tempo. If someone is still interested in analysing this, what happens after 24.Kh7!?
[d]r7/ppp2ppk/7p/1bpBN3/q7/P3B1P1/5P2/R2R2K1 w - - 4 25

[Leto]

This analysis contributes 32.Bd2! which is even more convincing.
With hindsight 24.Kh8? appears to be an error in critical position, loosing a tempo. If someone is still interested in analysing this, what happens after 24.Kh7!?
[d]r7/ppp2ppk/7p/1bpBN3/q7/P3B1P1/5P2/R2R2K1 w - - 4 25

I had Stockfish September 8 Syzygy play the black pieces until move 34 when its eval dropped to plus 2 pawns. I turned it off and let Komodo 8 finish up the rest.


25. Bxf7 b6 26. Bg6+ Kg8 27. Rd2 Rf8 28. Bc2 Qa5 29. a4 Qc3 30. Rc1 Qxe5 31.
axb5 Qe8 32. Rb1 Rf6 33. Bf4 Qe7 34. Bb3+ Kh8 35. Rbd1 Rf8 36. Bc4 Qf6
37. Rd7 Qc3 38. Bf1 Qf3 39. Rd8 Kh7 40. Bd3+ 1-0

[BeyondCritics]

OK, i accept your analysis. Sooner or later white will trade knight against bishop and then simply wins with his pair of bishops.
Therefore i propose another defence: 22..d5!?
[d]r5k1/pppb1pp1/7p/2Pp4/q7/P3BNP1/5PB1/R2R2K1 w - - 0 23
The idea is to bring the bishop to c6, keeping the position closed and hoping for the best. E.g.
23.Rxd5 Bc6 24.Rd3 Re8 25.Bf4 Re7 26.Rc1 g5!? 27.Be3 f6
White is better but it is a long way to realize it.
Any objections?

[BeyondCritics]

Further looking at 22..d5! convinces me, that this move is rather good and now my assessment is "unclear", that means something like "no clear plan for both".

[Leto]

OK, i accept your analysis. Sooner or later white will trade knight against bishop and then simply wins with his pair of bishops.
Therefore i propose another defence: 22..d5!?
[d]r5k1/pppb1pp1/7p/2Pp4/q7/P3BNP1/5PB1/R2R2K1 w - - 0 23
The idea is to bring the bishop to c6, keeping the position closed and hoping for the best. E.g.
23.Rxd5 Bc6 24.Rd3 Re8 25.Bf4 Re7 26.Rc1 g5!? 27.Be3 f6
White is better but it is a long way to realize it.
Any objections?

This looks good, if there's a win for white it's not simple to find. Here's a run I did:

23. Rxd5 Bc6 24. Rd3 Re8 25. Bf4 Re7 26. Rc1 g5 27. Be3 f6 28. Rcc3 Kf7 29. Kh2
Be4 30. Rd8 Kg6 31. Kg1 Bc6 32. Rd4 Qb5 33. Rdd3 Be4 34. Rd8 Qe2 35. Rd2 Qb5
36. Nd4 Qa5 37. Ne2 Bxg2 38. Kxg2 h5 39. Rcd3 Re8 40. c6 b6 41. Nd4 Re7 42. Rd1
Qa4 43. Rc1 Qa5 44. Bd2 Qd5+ 45. f3 Re4 46. fxe4 Qxe4+ 47. Rf3 Qxd4 48. Bc3 Qd5
49. Kf2 Qc5+ 50. Ke2 Qc4+ 51. Ke1 Qe4+ 52. Kf2 h4 53. Re1 hxg3+ 54. Kxg3 Qh4+
55. Kg2 Qg4+ 56. Rg3 Qc4 57. Re7 Qxc6+ 58. Kf2 Qc5+ 59. Rge3 Qf5+ 60. Kg1 Qg4+
61. Kf1 Qf5+ 62. Kg2 Qg4+ 63. Rg3 Qc4 64. Be1 f5 65. Bc3 Qd5+ 66. Kh2 f4 67.
Rg7+ Kh5 68. R3xg5+ Qxg5 1/2-1/2