King forced to abandon the back rank to escape an imminent mating threat.

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

SAE concept sae_18697 fires when king forced to abandon the back rank to escape an imminent mating threat.. It appears in 3 of 9,950 Climbchess puzzles (0.0%), spanning ELO 844–844 (median 844).

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This page documents King forced to abandon the back rank to escape…, 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:

King forced to abandon the back rank to escape an imminent mating threat.

This pattern fires in 3 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 844 to 844, with a median rating of 844. 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:

• Detects an active black bishop in an endgame, typically on a central or… — similarity 0.025
• Active bishop (either colour) in an endgame with back-rank mating threats or… — similarity 0.021
• A rook poised to deliver or support a back-rank mate, often on an open file… — similarity 0.019
• Rook operating on an open file or rank as the key piece in a mating attack or… — similarity 0.003
• Detects king-and-pawn endgames with kings in opposition or near-opposition… — similarity 0.003

Example puzzles

Below are 3 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle 01HU7 — ELO 844, themes: endgame, mate, mateIn1, side to move: Black
• Puzzle 01HU7_F — ELO 844, themes: endgame, mate, mateIn1, side to move: White
• Puzzle 01HU7_M — ELO 844, themes: endgame, mate, mateIn1, side to move: Black

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).