White 151 vs Black 896

The two setups

White: setup #151 N R B N Q K R B

King on the f-file, rooks on b, g, queen on the e-file; one 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 151 gives White +0.21 (Morozov Balance Index, 400M nodes).

Black: setup #896 B B R K Q R N N

King on the d-file, rooks on c, f, queen on the e-file; one 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 896 gives White +0.38 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B, 3.2B nodes) the evaluation is exactly 0.00 each time, reaching search depth 56.

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 agreed early: from 100 thousand to 128 million nodes the evaluation never left ±9 cp.

For comparison, in symmetric play setup 151 gives White +0.21 and setup 896 gives White +0.38: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.

The engine's first choice for White is g3; the alternatives are slightly weaker but keep the game level.

Along the engine's main line (30 moves) the evaluation stayed within ±18 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 0, drawn 10, Black won 0 (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 16 000 000 000 nodes.

Swap the two setups, giving White the black back rank and Black the white one, and the evaluation jumps to +126. The same two armies dealt the other way round are no longer balanced at all: that is how precisely this pair pays for the first move.

Independent engines, run on the same position:

• Berserk 14: 0
• Lc0 0.32.1: -1

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 +20, Black +119, difference -99. A balanced pair needs White's setup to be weaker by about the price of the first move.

Extended self-play: 160 games, 0 White wins, 160 draws, 0 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| 18 cp, mean 3.9 cp, final 0 cp.

Engine self-play

10 games at 500 000 nodes per move: White won 0, drawn 10, Black won 0 — White scored 50.0%. Average length 46.0 moves.

1. g3 f5 2. d4 Qg6 3. Qb4 Nf6 4. Bf4 O-O 5. Qxe7 Qh5 6. Bf3 Qh3+ 7. Bg2 Qh5 8. Bf3 Qh3+ 9. Bg2 Qh5

1. g3 f5 2. b4 Nf6 3. d4 Qh5 4. Bg2 Ng4 5. Rh1 c6 6. c4 b6 7. c5 Bb7 8. Nc2 f4 9. gxf4 O-O 10. h3 Nh6 11. Rb3 Bxf4 12. Bxf4 Rxf4 13. Ra3 Ra8 14. Qc3 Ng6 15. Bf3 Qh4 16. Nde3 Rf7 17. Ng2 Qf6 18. h4 Nf5 19. h5 Ngh4 20. Nxh4 Nxh4 21. Rh3 d6 22. cxb6 axb6 23. Rxa8+ Bxa8 24. Ke1 Qg5 25. Qe3 Qxe3 26. fxe3 Nxf3+ 27. exf3 Bb7 28. Kf2 c5 29. bxc5 bxc5 30. dxc5 dxc5 31. a4 Rf8 32. h6 g6 33. Na3 Rf5 34. Rg3 Kf7 35. Nb5 Rh5 36. Rg1 Rxh6 37. Rc1 Rh5 38. e4 Bc6 39. Ke3 c4 40. Na3 c3 41. Nb1 Bxa4 42. Nxc3 Bc6 43. Ne2 Bb7 44. Rb1 Ba6 45. Nd4 Rc5 46. Rb6 Bc8 47. f4 e5 48. fxe5 Rxe5 49. Nb5 Bh3 50. Kf4 Re7 51. Nd4 Kg7 52. e5 Re8 53. Rb7+ Kh6 54. Rb2 Bc8 55. Rh2+ Kg7 56. Rc2 Rf8+ 57. Ke4 Bb7+ 58. Ke3 Bd5 59. Rc5 Bg8 60. Ke4 Ra8

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 151 / 896 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): bbrkqrnn/pppppppp/8/8/8/8/PPPPPPPP/NRBNQKRB w BGcf - 0 1

Mirror twin: White 802 vs Black 63 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 32.