White 522 vs Black 622

The two setups

White: setup #522 R N Q K B B N R

King on the d-file, rooks on a, h, queen on the c-file; no 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 522 gives White +0.42 (Morozov Balance Index, 400M nodes).

Black: setup #622 R N Q K R B B N

King on the d-file, rooks on a, e, queen on the c-file; no bishop starts in a corner; the knights start away from the centre. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 622 gives White +0.32 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B, 3.2B nodes) the evaluation never left ±3 centipawns of equality, reaching search depth 60.

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 +16 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 522 gives White +0.42 and setup 622 gives White +0.32: 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 Nc3, and 3 first moves are within 10 cp of it.

Along the engine's main line (30 moves) the evaluation stayed within ±19 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: 0
• Lc0 0.32.1: +3

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 0, Black +50, difference -50. 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

30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 19 cp, mean 2.6 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 49.8 moves.

1. Nc3 e5 2. e4 d6 3. d3 Ng6 4. Nge2 Nc6 5. Nd5 Nd4 6. h4 Ne7 7. c4 c6 8. Nxd4 cxd5 9. Nb5 Qd7 10. Bd2 f5 11. Be2 fxe4 12. dxe4 dxc4 13. a4 Nc6 14. O-O Nd4 15. Bh5 g6 16. Bd1 d5 17. exd5 Bxd5 18. Qc3 O-O-O 19. Nxd4 exd4 20. Qxd4 Re4 21. Qc3 h6 22. Qg3 Bd6 23. f4 g5 24. Bf3 gxf4 25. Qg4 Qxg4 26. Bxg4+ Kc7 27. Bf3 Bc5+ 28. Kh2 Rd4 29. Bxd5 R8xd5 30. Bxf4+ Kb6 31. Rf3 h5 32. Bg3 Bd6 33. Kh3 Bxg3 34. Kxg3 Rd3 35. Rc1 R5d4 36. Kf2 Rxh4 37. b4 Rxf3+ 38. gxf3 a5 39. bxa5+ Kxa5 40. Ke3 Kxa4 41. Ra1+ Kb5 42. f4 Kc5 43. Rf1 Rh3+ 44. Ke4 Rd3 45. f5 Rd8 46. f6 Re8+ 47. Kf5 b5 48. f7 Rf8 49. Kg6 c3 50. Kg7 Rxf7+ 51. Kxf7 b4 52. Kg6 Kc4 53. Kxh5 c2 54. Re1 Kb3 55. Kg6 Kb2 56. Re2 Kb1 57. Re8 c1=Q 58. Re5 b3 59. Rh5 b2 60. Re5 Qc4

1. Nc3 Nc6 2. e4 d6 3. Nge2 e5 4. d3 Ng6 5. Nd5 Nce7 6. c4 c6 7. Ba5+ b6 8. Bxb6+ axb6 9. Nxb6 Qa6 10. Nxa8 Qxa8 11. g3 f5 12. Bh3 fxe4 13. dxe4 c5 14. O-O Nc6 15. b4 cxb4 16. a3 b3 17. Rb1 Na5 18. Nc3 Bxc4 19. Qe3 Ke7 20. Rfc1 Kf7 21. Na4 Qa6 22. Nb6 d5 23. exd5 Bd3 24. d6 Bxd6 25. Qf3+ Kg8 26. Rc8 Rxc8 27. Bxc8 Qxb6 28. Be6+ Kh8 29. Qxd3 Bxa3 30. Bxb3 Qd6 31. Bd5 Nc6 32. Ra1 Bc5 33. Ra6 Nb4 34. Rxd6 Nxd3 35. Rd8+ Nf8 36. Rc8 Bd6 37. Rd8 Be7 38. Re8 Bc5 39. Rc8 Bd6 40. Rd8 Be7

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 522 / 622 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): rnqkrbbn/pppppppp/8/8/8/8/PPPPPPPP/RNQKBBNR w AHae - 0 1

Mirror twin: White 533 vs Black 244 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 72.