White 452 vs Black 897

The two setups

White: setup #452 R B B N N K Q R

King on the f-file, rooks on a, h, queen on the g-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 452 gives White +0.29 (Morozov Balance Index, 400M nodes).

Black: setup #897 B R K B Q R N N

King on the c-file, rooks on b, f, queen on the e-file; one 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 897 gives White +0.39 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±3 centipawns of equality, 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 shallow rungs agreed early: from 100 thousand to 128 million nodes the evaluation never left ±8 cp.

For comparison, in symmetric play setup 452 gives White +0.29 and setup 897 gives White +0.39: 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 d4, and 3 first moves are within 10 cp of it.

Along the engine's main line (24 moves) the evaluation stayed within ±11 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 9, Black won 1 (White scored 45.0%).

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 held exactly 0.00 up to 1 600 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: -5
• Lc0 0.32.1: +1

Independent confirmations: 2 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 +32, Black +57, difference -25. A balanced pair needs White's setup to be weaker by about the price of the first move.

Extended self-play: 10 games, 0 White wins, 9 draws, 1 Black wins, White scored 45.0%.

Best first moves

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

Main-line play-out

24 moves, 5 000 000 nodes per half-move. Largest |evaluation| 11 cp, mean 1.6 cp, final 0 cp.

Engine self-play

10 games at 500 000 nodes per move: White won 0, drawn 9, Black won 1 — White scored 45.0%. Average length 45.0 moves.

1. f3 b6 2. d4 e5 3. dxe5 Ng6 4. Nd3 f6 5. exf6 Nxf6 6. c3 c5 7. b4 c4 8. Ne1 Ne5 9. Qd4 Bc7 10. a4 Qh5 11. Ne3 O-O 12. h4 Rbe8 13. b5 Qf7 14. h5 Nxh5 15. Rh3 g6 16. Ba3 d6 17. Ba2 Nf4 18. Rh4 Ne6 19. Qd2 Qf6 20. Rh1 Rf7 21. N1c2 Bxf3 22. O-O-O Be4 23. Rhf1 Qh4 24. Rxf7 Kxf7 25. Nd4 Nf4 26. Bxc4+ d5 27. Bb3 Ng4 28. Nxd5 Nxd5 29. Nf3 Qd8 30. Bxd5+ Bxd5 31. Qxd5+ Qxd5 32. Rxd5 Nf6 33. Rd3 Rxe2 34. Ng5+ Kg8 35. c4 h5 36. c5 Rxg2 37. Ne6 Rg3 38. Kc2 Rg2+ 39. Kb3 Rg3 40. Kc2 Be5 41. c6 h4 42. c7 Rg2+ 43. Kb3 Bxc7 44. Nxc7 g5 45. Rh3 Ne4 46. Nd5 Kf7 47. Kc4 Kg6 48. Bb4 Nf2 49. Re3 Rg4+ 50. Kb3 h3 51. Re6+ Kf5 52. Re2 Rg3+ 53. Kc4 Rg4+ 54. Kb3 Nd3 55. Ne3+ Kf4 56. Nd5+ Kf5 57. Ne3+ Kf4 58. Nd5+

1. d4 b6 2. Nd3 Ng6 3. f3 e5 4. dxe5 f6 5. exf6 Nxf6 6. a4 c5 7. Nc3 d5 8. Nb5 Qe7 9. Qe3 Ne4 10. c3 Qd7 11. O-O Bg5 12. f4 Be7 13. Ne5 Nxe5 14. fxe5 Rxf1+ 15. Kxf1 O-O-O 16. Bxe4 dxe4 17. Nd6+ Bxd6 18. exd6 a5 19. Qg3 e3 20. Bxe3 Qxd6 21. Qxd6 Rxd6 22. b4 Rf6+ 23. Kg1 Re6 24. Kf2 Rf6+ 25. Ke1 Bxg2 26. Kd2 Rd6+ 27. Ke1 Rf6 28. Ra3 Re6 29. Kf2 Bc6 30. bxc5 bxc5 31. Bxc5 Rh6 32. Kg1 Rg6+ 33. Kf1 Rh6 34. Bg1 Rh4 35. c4 g5 36. Bb6 Rxh2 37. Re3 Kd7 38. Rd3+ Ke6 39. c5 Rh1+ 40. Kf2 Bxa4

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 452 / 897 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): brkbqrnn/pppppppp/8/8/8/8/PPPPPPPP/RBBNNKQR w AHbf - 0 1

Mirror twin (the same position mirrored): White 702 vs Black 59.