White 519 vs Black 424

The two setups

White: setup #519 R N B Q K N R B

King on the e-file, rooks on a, g, queen on the d-file; one 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 519 gives White +0.28 (Morozov Balance Index, 400M nodes).

Black: setup #424 R B N Q B N K R

King on the g-file, rooks on a, h, queen on the d-file; no 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 424 gives White +0.23 (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 59.

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 wandered between -15 and +20 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 519 gives White +0.28 and setup 424 gives White +0.23: 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 e4; the alternatives are slightly weaker but keep the game level.

Along the engine's main line (30 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 held exactly 0.00 up to 1 600 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: 0
• Lc0 0.32.1: -6

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 +50, Black +72, difference -22. 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

30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 16 cp, mean 3.5 cp, final +1 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 42.0 moves.

1. d4 d5 2. g3 c6 3. e4 dxe4 4. Bxe4 f5 5. Bd3 Qxd4 6. Bxf5 Qxd1+ 7. Kxd1 Nd6 8. Bh3 Bh5+ 9. Ke1 Bc7 10. Ne3 Re8 11. Nd2 Bg6 12. c3 e6 13. a4 Nd7 14. Nec4 O-O 15. Nxd6 Bxd6 16. Nc4 Bc5 17. Be3 Bxe3 18. fxe3 Nc5 19. Rf1 Rd8 20. b4 Rxf1+ 21. Bxf1 Nd3+ 22. Bxd3 Rxd3 23. Ra3 e5 24. Kf2 e4 25. Na5 Rd2+ 26. Ke1 Rd3 27. Kf2 Bh5 28. Ra2 Rxc3 29. Nxb7 Rc1 30. Rd2 Bf3 31. h4 Rh1 32. Rd8+ Kf7 33. Rd7+ Ke6 34. Nc5+ Ke5 35. Rxg7 Rh2+ 36. Kf1 Rh1+ 37. Kf2 Rh2+ 38. Kf1 Rh1+

1. e4 h5 2. g3 c6 3. Nc3 e6 4. d4 d5 5. Be3 Nd6 6. Nd2 Bc7 7. h4 f6 8. Bg2 Rh7 9. Qe2 Ba5 10. Bf4 Bg6 11. O-O Bxc3 12. bxc3 Bxe4 13. Bxe4 Nxe4 14. Nxe4 dxe4 15. Qxe4 Qd5 16. Rfe1 g6 17. Qe2 Rf7 18. Rab1 Qxa2 19. c4 Qa5 20. Bd6 Qf5 21. Rb3 Qg4 22. Qd3 a5 23. Reb1 Rd8 24. c5 Qf5 25. Qe2 a4 26. Rxb7 Rxb7 27. Rxb7 Ra8 28. Rb2 a3 29. Ra2 Qd5 30. c4 Qxd4 31. Bxf8 Kxf8 32. Qxe6 Kg7 33. Qxc6 Qxc4 34. Qxa8 Qxa2 35. Qa7+ Kh6 36. Qa8 Kg7 37. Qa7+ Kh6 38. c6 Qb1+ 39. Kh2 Qc2 40. c7 a2

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 519 / 424 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): rbnqbnkr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKNRB w AGah - 0 1

Mirror twin (the same position mirrored): White 530 vs Black 733.