White 73 vs Black 926
White starts from setup 73 (NNRBBKQR), Black from setup 926 (RKRQNBBN). In the encyclopedia since 2026-10-15: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
How to play with different setups
White sets up the pieces by position No. 73, Black by position No. 926, mirrored on their own side; the pawns stand as usual.
Moves as usual: White starts; everything else follows the Chess960 rules.
The two setups
White: setup #73 N N R B B K Q R
King on the f-file, rooks on c, h, queen on the g-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 73 gives White +0.31 (Morozov Balance Index, 400M nodes).
Black: setup #926 R K R Q N B B N
King on the b-file, rooks on a, c, 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 926 gives White +0.26 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±5 centipawns of equality, reaching search depth 55.
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 wandered between -17 and +19 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 73 gives White +0.31 and setup 926 gives White +0.26: 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 f4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the largest swing was 45 cp (around move 9), ending at -5 cp — the position stays playable for both sides.
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.
| Stage | Nodes | Depth | Eval, cp | Main line |
|---|---|---|---|---|
| S0 | 100 000 | 13 | -17 | 1. f4 f5 2. Qf2 Bxa2 3. O-O Nf6 4. Na3 Bf7 |
| S1 | 500 000 | 16 | 0 | 1. f4 e5 2. fxe5 Ng6 3. c4 f6 4. Qf2 fxe5 |
| S2 | 2 000 000 | 20 | +19 | 1. f4 g5 2. fxg5 Bg7 3. c3 f5 4. Nb3 Ng6 |
| S3 | 8 000 000 | 26 | +7 | 1. f4 e5 2. fxe5 Ng6 3. Qf2 Nxe5 4. O-O g6 |
| S4 | 32 000 000 | 34 | +8 | 1. f4 e5 2. fxe5 Ng6 3. Qf2 Nxe5 4. O-O g6 |
| S5 | 128 000 000 | 43 | 0 | 1. f4 e5 2. fxe5 Ng6 3. Qf2 Nxe5 4. O-O g6 |
| S6 | 400 000 000 | 49 | -5 | 1. f4 e5 2. fxe5 Ng6 3. Nc3 Nxe5 4. e4 g6 |
| S7 | 800 000 000 | 53 | 0 | 1. f4 e5 2. fxe5 Ng6 3. Nc3 Nxe5 4. e4 Nd6 |
| S8 | 1 600 000 000 | 55 | 0 | 1. f4 e5 2. fxe5 Ng6 3. Nc3 Nxe5 4. e4 Nd6 |
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.
| Nodes | Eval, cp |
|---|---|
| 4 000 000 000 | 0 |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair stays within the ±5 cp corridor up to 4 000 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: 0
- Lc0 0.32.1: -12
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 +18, Black +26, difference -8. 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.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | +4 | 39 | 1. f4 a5 2. c4 e5 3. fxe5 Ng6 4. Qf2 f6 5. e6 dxe6 |
| 2 | -10 | 38 | 1. c4 e5 2. f3 f5 3. d4 Qf6 4. Bc3 Ng6 5. h4 exd4 |
| 3 | -21 | 38 | 1. h4 a5 2. c4 e5 3. f3 f5 4. d4 Qf6 5. Nb3 exd4 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 45 cp, mean 20.3 cp, final -5 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | f4 | +7 | a5 | +13 |
| 2 | c4 | +10 | e5 | -10 |
| 3 | fxe5 | -20 | Ng6 | -19 |
| 4 | Qd4 | 0 | f6 | 0 |
| 5 | exf6 | 0 | Bd6 | 0 |
| 6 | O-O | 0 | Nxf6 | 0 |
| 7 | Qc3 | 0 | Qe7 | -14 |
| 8 | e3 | -15 | Ne4 | -33 |
| 9 | Qc2 | -31 | Qe5 | -45 |
| 10 | g3 | -36 | Ng5 | -43 |
| 11 | Nc3 | -33 | Be6 | -33 |
| 12 | Be2 | -40 | a4 | -30 |
| 13 | b3 | -28 | Bh3 | -29 |
| 14 | Rf2 | -30 | Qe6 | -35 |
| 15 | d4 | -36 | Bb4 | -31 |
| 16 | bxa4 | -38 | Bxc3 | -39 |
| 17 | d5 | -38 | Qxe3 | -29 |
| 18 | Qxc3 | -30 | Qxc3 | -29 |
| 19 | Bxc3 | -26 | Ne4 | -25 |
| 20 | Rf3 | -21 | Nxc3 | -17 |
| 21 | Rcxc3 | -11 | Rxa4 | -14 |
| 22 | Ra3 | -17 | Rxa3 | -17 |
| 23 | Rxa3 | -22 | c6 | -45 |
| 24 | dxc6 | -22 | bxc6 | -27 |
| 25 | Nb3 | -19 | Re8 | -22 |
| 26 | Kf2 | -20 | Ne5 | -16 |
| 27 | Nd4 | -13 | Ng4+ | -8 |
| 28 | Bxg4 | 0 | Bxg4 | -7 |
| 29 | Re3 | -2 | Rf8+ | -8 |
| 30 | Ke1 | -10 | Kc7 | -5 |
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 37.1 moves.
Sample game 1 (1/2-1/2)
1. f4 Ng6 2. f5 Ne5 3. Qf2 d5 4. d4 Nc4 5. b3 Ncd6 6. c4 Ne4 7. Qf3 g6 8. O-O N8d6 9. Bc2 Nxf5 10. Rd1 Ng5 11. Qf2 Nd6 12. Qf4 Ne6 13. Qf2 Ng5 14. Nc3 f5 15. Qe3 Bh6 16. c5 Nde4 17. b4 Nxc3 18. Qxc3 Ne4 19. Qb3 a6 20. a4 Qd7 21. b5 axb5 22. axb5 b6 23. Bg3 Nxg3 24. Qxg3 Qe6 25. Kh1 f4 26. Qf2 Bf7 27. Bd3 O-O 28. Nc2 Qf6 29. Nb4 Be6 30. Nc6 Bg7 31. cxb6 cxb6 32. Rc1 Bg4 33. h3 Bd7 34. Qf3 Bxc6 35. bxc6 Qe6 36. c7 Bxd4 37. Bb5 Kg7 38. Bc6 Rac8 39. Bb7 Be3 40. Bxc8 Rxc8 41. Rc3 h5 42. h4 Qd6 43. Rc2 Qd7 44. Rc3 Qd6 45. Rc2 Qe6 46. Rc3
Sample game 2 (1/2-1/2)
1. f4 f5 2. Qf2 Bxa2 3. c4 e6 4. d3 Bxb1 5. Rxb1 g5 6. fxg5 Qxg5 7. e4 Be7 8. Bd2 Qg8 9. exf5 Ng7 10. f6 Bxf6 11. O-O Nf5 12. Kh1 Ng6 13. Nb3 Rf8 14. Bf3 Qg7 15. Bb4 d6 16. Qe1 Ne5 17. Qe4 c5 18. Ba5 Rg8 19. g3 a6 20. d4 Nxf3 21. Rxf3 Nxd4 22. Nxd4 Bxd4 23. Qxe6 Qg6 24. Re1 Ka7 25. Rb3 Rab8 26. Qd5 Qg5 27. Qxg5 Rxg5 28. Bb6+ Ka8 29. Bc7 Rc8 30. Bxd6 b5 31. cxb5 c4 32. Ra3 Rxb5 33. Rxa6+ Kb7 34. Ra4 Bxb2 35. Re4 c3 36. Bf4 Kc6 37. Kg2 Rc5 38. Rab4 Rb5 39. Rec4+ Rc5 40. Re4 Rb5
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 73 / 926 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): rkrqnbbn/pppppppp/8/8/8/8/PPPPPPPP/NNRBBKQR w CHac - 0 1
Mirror twin: White 889 vs Black 36 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 321.