White 26 vs Black 743

The two setups

White: setup #26 N Q N R B B K R

King on the g-file, rooks on d, h, queen on the b-file; no bishop starts in a corner; the knights start away from the centre. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 26 gives White +0.36 (Morozov Balance Index, 400M nodes).

Black: setup #743 R K B N N Q R B

King on the b-file, rooks on a, g, queen on the f-file; one bishop starts in a corner; the knights start on central files. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 743 gives White +0.21 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation is exactly 0.00 each time, reaching search depth 55.

Admission rule: |cp| ≤ 5 at four budgets up to 4 billion nodes, no one-sided drift along the ladder, and confirmation by two independent engines — Berserk and Lc0 — each below its own median on symmetric positions. The same corridor is required at every deeper budget (8 G, 16 G) at which the pair has been evaluated.

The shallow rungs wandered between -4 and +24 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 26 gives White +0.36 and setup 743 gives White +0.21: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.

White is not forced into a single path: the best first move is c4, and 3 first moves are within 10 cp of it.

Along the engine's main line (17 moves) the evaluation stayed within ±13 cp the whole way: the balance holds as the pieces come out, not only on move one.

Engine self-play agrees: 10 games, White won 1, drawn 8, Black won 1 (White scored 50.0%).

Verification ladder

Nine independent searches of the starting position, each with a larger node budget. Evaluation in centipawns from White's point of view.

Deep verification

The search ladder reaches 1.6 billion nodes; admission needs a 4-billion rung and two further engines on top of that. Beyond even that, every pair was re-checked at budgets up to ten times larger and in thousands of self-play games. This section shows what each check returned for this pair.

This pair stays within the ±5 cp corridor up to 4 000 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: +1
• Lc0 0.32.1: +6

Independent confirmations: 3 of 3. An engine counts as confirming when its reading of the pair is closer to equality than its own reading of a typical symmetric Chess960 position (+10 for Berserk, +18 for Lc0). Where only one engine confirms, the pair is balanced according to that engine alone, and this page says so.

Own weight of each setup, measured against the classical array: White +82, Black +101, difference -19. A balanced pair needs White's setup to be weaker by about the price of the first move.

Extended self-play: 10 games, 1 White wins, 8 draws, 1 Black wins, White scored 50.0%.

Best first moves

The 3 best first moves for White, searched together at 400 000 000 nodes.

Main-line play-out

17 moves, 5 000 000 nodes per half-move. Largest |evaluation| 13 cp, mean 1.7 cp, final 0 cp.

Engine self-play

10 games at 500 000 nodes per move: White won 1, drawn 8, Black won 1 — White scored 50.0%. Average length 47.2 moves.

1. c4 d6 2. d4 f5 3. Nc2 f4 4. a4 g5 5. b4 a6 6. a5 Qf7 7. b5 Bf5 8. Nd3 axb5 9. cxb5 Nf6 10. a6 Nd5 11. e3 fxe3 12. Nxe3 Bxd4 13. Nxd5 Qxd5 14. Nb4 Qf7 15. Bd3 Bxd3 16. Qxd3 Bb6 17. O-O Rf8 18. Nd5 Ne6 19. Bd2 Nc5 20. Qc4 bxa6 21. Bxg5 axb5 22. Qxb5 Ra5 23. Qc4 Nd7 24. h4 Kb7 25. Nxb6 Nxb6 26. Qe4+ Nd5 27. Rb1+ Kc6 28. Rfc1+ Kd7 29. Qc2 Rc5 30. Qa4+ c6 31. Rb7+ Nc7 32. Rc2 Rxc2 33. Qxc2 Ra8 34. Qb1 Rc8 35. Qe4 h5 36. f4 Qe6 37. Qa4 Qe3+ 38. Kh2 Qe2 39. Qd4 Ra8 40. Qb6 Rc8 41. Qb1 c5 42. Rb2 Qe6 43. Qd1 Nd5 44. Qxh5 c4 45. Re2 Qf5 46. Re1 c3 47. Qe2 c2 48. g4 Qf7 49. Rc1

1. c4 g5 2. b4 f5 3. d4 g4 4. Nab3 Ne6 5. a4 Nd6 6. c5 Ne4 7. g3 h5 8. Bg2 h4 9. f4 gxf3 10. exf3 N6g5 11. O-O Nf6 12. Ne2 Nd5 13. f4 Ne4 14. Qd3 hxg3 15. Nxg3 Qg7 16. b5 d6 17. Kh1 Be6 18. a5 a6 19. Rb1 axb5 20. Qxb5 c6 21. Qd3 Ra7 22. a6 Rxa6 23. Na5 Nxg3+ 24. hxg3 Kc8 25. Nxb7 Ra4 26. Rf3 Kd7 27. Bf2 Rga8 28. Kg1 Qg8 29. Qd1 Ra2 30. cxd6 exd6 31. Rd3 Bf6 32. Qe1 R8a4 33. Qc1 Ra7 34. Nxd6 Kxd6 35. Rdb3 Kc7 36. Rb8 Qg7 37. R8b6 Qd7 38. R6b2 Qe8 39. g4 Rxb2 40. Qxb2 Qa8 41. Qc1 Kd7 42. g5 Be7 43. g6 Qg8 44. Rb6 Rc7 45. Rb3 Qxg6 46. Rg3 Qf6 47. Rh3 Rb7 48. Qc2 Bf7 49. Kh1 Rb8 50. Bh4 Qxd4 51. Bf2 Qb2 52. Qxf5+ Be6 53. Qe5 Qxe5 54. fxe5 Bxh3 55. Bxh3+ Kc7 56. Bg4 Nf4 57. Kh2 Nd3 58. Bg3 Nxe5 59. Bxe5+ Bd6 60. Bxd6+ Kxd6 61. Bd1 c5 62. Kg3 Ke5 63. Kf3 Kd4 64. Bc2 c4 65. Bh7 Rb3+ 66. Kf4 Rd3 67. Bf5 c3 68. Be6 c2 69. Kf5 c1=Q 70. Kg6 Qc7

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 26 / 743 in the app's encyclopedia, then choose how to play.

• Local game — two players on one device, with a clock.
• With a mentor — a clearly labelled training bot with hints, at your level.
• Challenge a friend — an online game by link; both players get the same pair, colours swap on rematch.

Play this pair against the computer, right here Play a friend

FEN (Shredder, castling rights by rook files): rkbnnqrb/pppppppp/8/8/8/8/PPPPPPPP/NQNRBBKR w DHag - 0 1

Mirror twin: White 933 vs Black 402 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 149.