White 62 vs Black 109

The two setups

White: setup #62 N N R Q K B B R

King on the e-file, rooks on c, h, queen on the d-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 62 gives White +0.36 (Morozov Balance Index, 400M nodes).

Black: setup #109 Q N R B N K B R

King on the f-file, rooks on c, h, queen on the a-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 109 gives White +0.10 (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 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 agreed early: from 100 thousand to 128 million nodes the evaluation never left ±9 cp.

For comparison, in symmetric play setup 62 gives White +0.36 and setup 109 gives White +0.10: 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 f3, and 3 first moves are within 10 cp of it.

Along the engine's main line (21 moves) the evaluation stayed within ±16 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 4 000 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: -3
• Lc0 0.32.1: -4

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 +15, Black +32, difference -17. 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, 10 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

21 moves, 5 000 000 nodes per half-move. Largest |evaluation| 16 cp, mean 2.5 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 36.2 moves.

1. c4 f5 2. f3 c5 3. Bf2 Bf7 4. e3 O-O 5. Be2 e5 6. O-O Nc6 7. Nc2 b6 8. Nc3 Bg5 9. Nd5 Qb8 10. f4 exf4 11. exf4 Bf6 12. Nxf6+ Nxf6 13. d4 d5 14. cxd5 Nxd5 15. Ba6 Rcd8 16. Qf3 b5 17. dxc5 Nc7 18. Rcd1 Bd5 19. Qa3 Be4 20. Nd4 Kh8 21. Nxc6 Bxc6 22. Qa5 Rxd1 23. Rxd1 Qe8 24. Rd4 Qg6 25. Bg3 Qe6 26. Bf2 Qg6 27. Bg3 Qe8 28. Bf2

1. e4 f5 2. exf5 Bxa2 3. f3 Bf7 4. d4 O-O 5. Bf2 a5 6. c4 Na6 7. Nc2 Nd6 8. Ne3 e6 9. fxe6 dxe6 10. Nc3 Bg5 11. Bd3 Nf5 12. Nxf5 exf5 13. O-O Bxc1 14. Qxc1 Nb4 15. Bxf5 Bxc4 16. Bxc8 Qxc8 17. Rd1 Nd3 18. Qc2 Nxf2 19. Qxf2 Bb3 20. Ra1 b6 21. Re1 Qd7 22. d5 b5 23. Qc5 b4 24. Re7 Qd6 25. Ne4 Qxc5+ 26. Nxc5 Bxd5 27. Rxc7 Ra8 28. Rd7 Bc6 29. Rc7 Bd5 30. Rd7 Bc4 31. Rc7

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 62 / 109 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): qnrbnkbr/pppppppp/8/8/8/8/PPPPPPPP/NNRQKBBR w CHch - 0 1

Mirror twin: White 900 vs Black 856 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 269.