White 171 vs Black 745

The two setups

White: setup #171 N R N K B Q R B

King on the d-file, rooks on b, g, queen on the f-file; one 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 171 gives White +0.24 (Morozov Balance Index, 400M nodes).

Black: setup #745 R K N B B N Q R

King on the b-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 745 gives White +0.13 (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 54.

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 -9 and +21 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 171 gives White +0.24 and setup 745 gives White +0.13: 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 f4, and 3 first moves are within 10 cp of it.

Along the engine's main line (14 moves) the evaluation stayed within ±21 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: -1
• Lc0 0.32.1: -5

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 +48, Black +39, difference +9. 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

14 moves, 5 000 000 nodes per half-move. Largest |evaluation| 21 cp, mean 6.1 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 42.2 moves.

1. c4 c6 2. f4 f6 3. d3 a5 4. Nc2 e5 5. g3 d5 6. cxd5 cxd5 7. b4 a4 8. Qg2 Ne7 9. b5 Qe6 10. Bb4 Bb6 11. e3 Nd7 12. g4 Nc5 13. Nd4 Qc8 14. fxe5 fxe5 15. Qg3 Qc7 16. Bxc5 Qxc5 17. Qxe5+ Ka7 18. Nce2 Rf8 19. Rc1 Qb4 20. a3 Qxa3 21. Rc3 Qa1+ 22. Rc1 Qa3 23. Rc3 Qa1+ 24. Rc1

1. c4 e5 2. g3 a5 3. f4 f6 4. d3 c6 5. Nc2 h5 6. e4 d6 7. Ne2 Ne6 8. f5 Nc5 9. Nc3 Bb6 10. Bf2 g6 11. O-O-O gxf5 12. exf5 Bd7 13. Kb1 Ne7 14. Ne4 Nxf5 15. Nxf6 Qg7 16. Nxd7+ Qxd7 17. Be4 Ng7 18. Bxc5 Bxc5 19. d4 exd4 20. Qd3 Kc7 21. a3 Rhf8 22. Rgf1 Qe7 23. Nxd4 Rxf1 24. Rxf1 Rf8 25. Rxf8 Qxf8 26. Qf3 Qe8 27. Ne2 Ne6 28. Qf5 Ng7 29. Qg6 Qe5 30. Bf3 Kb6 31. Ka2 Be3 32. Qh7 Qf6 33. Qe4 Bf2 34. Qd3 Qe5 35. Qb3+ Kc7 36. Nf4 Bg1 37. Qc2 Ne6 38. Nxe6+ Qxe6 39. Bxh5 Qh3 40. Bd1 Bxh2

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 171 / 745 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): rknbbnqr/pppppppp/8/8/8/8/PPPPPPPP/NRNKBQRB w BGah - 0 1

Mirror twin: White 785 vs Black 409 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 478.