This feature detects a king on the back rank (or 7th rank for black) that is under attack by a queen, where the king is not directly attacked by other pieces.

By Climbchess Research · 2026-05-08 · 3 min read · Updated May 8, 2026

SAE concept sae_27662 fires when this feature detects a king on the back rank (or 7th rank for black) that is under attack by a queen, where the king is not directly attacked by other pieces.. It appears in 2 of 9,950 Climbchess puzzles (0.0%), spanning ELO 1893–1893 (median 1893).

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This page documents This feature detects a king on the back rank (or…, one of 4,505 interpretable chess concepts extracted from Leela Chess Zero via sparse autoencoders. The full feature description from our SAE labelling pipeline reads:

This feature detects a king on the back rank (or 7th rank for black) that is under attack by a queen, where the king is not directly attacked by other pieces.

This pattern fires in 2 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 1893 to 1893, with a median rating of 1893. That distribution tells you whether this is a beginner cue or a master-level subtlety.

Pattern statistics

Related concepts

The five concepts most often co-firing alongside this one (Jaccard similarity over the puzzle co-occurrence graph) are:

• King on rank 2 or 7 in a simplified endgame, often with passed pawns or mating… — similarity 0.006
• A square dominated by a white knight where white has equal or superior control… — similarity 0.003
• Active rook delivering or threatening a decisive mating attack in the endgame… — similarity 0.003
• A knight (either colour) that is actively supported by a friendly piece, with… — similarity 0.003
• A well-supported white knight on an outpost square that is contested by black. — similarity 0.002

Example puzzles

Below are 2 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle x04fe — ELO 1893, themes: discoveredAttack, endgame, hookMate, side to move: Black
• Puzzle x04fe_F — ELO 1893, themes: discoveredAttack, endgame, hookMate, side to move: White

How to use this page

If you want to train this pattern, open the Climbchess trainer and filter for puzzles tagged with this concept. The trainer surfaces them at the right difficulty for your current rating, and tracks how often you spot the cue versus miss it. You can also browse the related concepts above to see neighbouring ideas in feature space.

Climbchess concepts are not heuristics written by a human author. Each one corresponds to a single direction in the residual stream of Leela Chess Zero that activates on a specific board feature, then was labelled by reading the top-activating positions. This makes the catalogue exhaustive (every Leela-detectable pattern is in here somewhere) and falsifiable (you can replay our extraction).