Coach definition, not a live verdict. These pages show how the X-ray Coach defines this concept and where its thresholds sit, sourced from the coach's own code. Unlike the tactic pages, nothing here runs a live detector — example boards illustrate the rule, they don't execute it.
What it means
- Strategy grades the positions where the engine offers many nearly-equal moves: nothing to calculate, nothing to win by force — just the better plan.
- A position is scored only if it passes EVERY rule below. Ones that fail aren't held against you here; they belong to other concepts (Tactics, Attack, Endgame).
- The definition is David's (Atlas card “2. Strategy”). It replaced an earlier rule that asked for the top five moves within 0.50.
The exact rule the X-ray Coach applies
- Eight moves, close together: the engine's top 8 moves must sit within 1.00 of each other. Fewer than eight playable moves — or a forced mate anywhere in them — means the position isn't quiet, so it doesn't count.
- Position not already decided: the evaluation before the move must be within ±2.00. Once someone is winning outright, the choice stops being strategic.
- Material within one pawn, counted as P1 N3 B3 R5 Q9. A wider gap is a different kind of decision.
- No opposite castling: excluded when one king stands on the a/b/c files and the other on f/g/h. A king still on d/e belongs to neither wing, so it is not “opposite”.
- Middlegame only, and no tactic: openings and endgames are excluded by game phase; every remaining position is classified by Koga and anything tagged as a tactic is dropped. A quiet preparatory move is not a tactic.
How it's scored
- Your score is the average evaluation you concede on the qualifying positions, compared against players at your rating.
- Attacking positions with one correct plan (a King's Indian-style kingside attack, say) do NOT qualify, by design: when a single plan is right, the engine's 2nd-8th moves are far worse than the best one, so the ladder is wide by construction. Those positions need their own rule rather than a looser threshold here.
Why it matters
David curated 65 positional middlegame positions as the reference set; this definition admits 64 of them. The one it turns away is Botvinnik-Yudovich (URS-ch08) at +2.05 — five hundredths outside the ±2.00 line of the definition itself. The rule it replaced admitted only 59 of the 65. On real student games the gate keeps roughly one middlegame position in six.
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