White 24 vs Black 98

The two setups

White: setup #24 N B Q N B R K R

King on the g-file, rooks on f, h, queen on the c-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 24 gives White +0.42 (Morozov Balance Index, 400M nodes).

Black: setup #98 B Q N R N B K R

King on the g-file, rooks on d, h, queen on the b-file; one bishop starts in a corner; the knights start on central files. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 98 gives White +0.16 (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 53.

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 ±15 cp.

For comparison, in symmetric play setup 24 gives White +0.42 and setup 98 gives White +0.16: 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 2 first moves are within 10 cp of it.

Along the engine's main line (30 moves) the largest swing was 42 cp (around move 11), ending at 0 cp — the position stays playable for both sides.

Engine self-play agrees: 10 games, White won 0, drawn 4, Black won 6 (White scored 20.0%).

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: +3
• Lc0 0.32.1: +8

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 +63, Black +110, difference -47. 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, 4 draws, 6 Black wins, White scored 20.0%.

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| 42 cp, mean 16.1 cp, final 0 cp.

Engine self-play

10 games at 500 000 nodes per move: White won 0, drawn 4, Black won 6 — White scored 20.0%. Average length 64.2 moves.

1. d4 b6 2. h4 c5 3. c3 h5 4. e4 e6 5. Bd2 Ne7 6. Nb3 Rc8 7. Bf4 Nd6 8. Re1 cxd4 9. Nxd4 Ng6 10. Bg3 Rh6 11. a4 a6 12. Bd3 Qb7 13. Nf3 b5 14. Qc2 Be7 15. e5 Ne8 16. Rh3 d6 17. Ne3 Rd8 18. exd6 Nxd6 19. axb5 axb5 20. Ra1 Bf6 21. Ng5 Qe7 22. Bxd6 Qxd6 23. Ra7 Nf4 24. Bh7+ Kf8 25. Rxf7+ Ke8 26. Rg3 Bxg5 27. hxg5 Kxf7 28. gxh6 gxh6 29. Bg8+ Ke8 30. Rg7 Rd7 31. Rxd7 Qxd7 32. c4 Kd8 33. Bh7 bxc4 34. Qxc4 Nh3+ 35. gxh3 Qxh7 36. Kh2 Qg6 37. Qf4 Kd7 38. b4 Bc6 39. Qd4+ Kc7 40. Qa7+ Bb7 41. Qd4 Qg5 42. f4 Qg6 43. Qe5+ Kd7 44. f5 exf5 45. Qxf5+ Qxf5 46. Nxf5 Be4 47. Ng3 Bg6 48. h4 Kc6 49. Ne2 Kb5 50. Kg3 Kxb4 51. Kf4 Kc4 52. Ke5 Be8 53. Nf4 Kc3 54. Nd5+

1. f3 h5 2. Bh4 c5 3. c3 Qf4 4. Bg3 Qg5 5. Bf2 h4 6. Be3 Qh5 7. Nf2 e6 8. Rd1 Ne7 9. Nc2 Nd5 10. g4 Qe5 11. d4 cxd4 12. cxd4 Qb8 13. Bd2 Rc8 14. Nd3 b6 15. e4 Ne7 16. O-O Nd6 17. Be1 Ng6 18. Qe3 Be7 19. Qe2 O-O 20. Bd2 b5 21. a3 Qb6 22. Bc1 a5 23. Nc5 Qa7 24. Nd3 Bc6 25. Qf2 Qb8 26. Ne3 b4 27. axb4 Ba4 28. e5 Nb5 29. Nf5 Bd8 30. Rde1 exf5 31. gxf5 Nxd4 32. fxg6 Bc2 33. bxa5 Bxb1 34. Qxd4 Qb5 35. e6 dxe6 36. Ne5 Bxa5 37. gxf7+ Rxf7 38. Qd6 Bxe1 39. Rxe1 Rff8 40. Qxe6+ Kh7 41. Qg4 Bf5 42. Qxh4+ Kg8 43. Qg3 Rc2 44. Bh6 Qb6+ 45. Be3 Qxb2 46. Kh1 Qb7 47. h4 Re8 48. Bf4 Rb2 49. h5 Kh7 50. h6 g6 51. Kg1 Qb4 52. Kh1 Re6 53. Rg1 Qb7 54. Re1 Re7 55. Rg1 Qa6 56. Qh4 Reb7 57. Bg3 Qe2 58. Qc4 Rc2 59. Qxe2 Rxe2 60. Rg2 Rb1+ 61. Kh2 Rbb2 62. Rxe2 Rxe2+ 63. Kh1 Kxh6 64. Nc6 Kg5 65. Kg1 Bh3 66. Be5 Rg2+ 67. Kh1 Ra2 68. Kg1 Re2 69. Bc7 Rg2+ 70. Kh1 Rf2 71. Nd4 Rd2 72. Nc6 Rf2 73. Ne5 Rc2 74. Bd6 Kf5 75. f4 Ke6 76. Bb8 Bf5 77. Kg1 Be4 78. Kf1 Rc8 79. Ba7 g5 80. fxg5 Kxe5 81. Kf2 Bf5 82. Ke3 Rc3+ 83. Kd2 Rc2+ 84. Ke3 Rc3+ 85. Ke2 Ke4 86. Kd2 Rc8 87. Bb6 Kf3 88. Kd1 Rb8 89. Bc7 Rb7 90. Bh2 Rh7 91. Bd6 Rd7

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 24 / 98 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): bqnrnbkr/pppppppp/8/8/8/8/PPPPPPPP/NBQNBRKR w FHdh - 0 1

Mirror twin: White 941 vs Black 855 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 141.