A white pawn on the 4th or 5th rank, attacked by a white bishop, with no black attackers.

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

SAE concept sae_21601 fires when a white pawn on the 4th or 5th rank, attacked by a white bishop, with no black attackers.. It appears in 1 of 9,950 Climbchess puzzles (0.0%), spanning ELO 889–889 (median 889).

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This page documents A white pawn on the 4th or 5th rank, attacked by…, 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:

A white pawn on the 4th or 5th rank, attacked by a white bishop, with no black attackers.

This pattern fires in 1 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 889 to 889, with a median rating of 889. 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:

• A vulnerable back-rank pawn or king position creates a skewer or deflection… — similarity 0.034
• Rook endgame with active rook placement, often involving deflection… — similarity 0.026
• A black piece on a contested square where black retains at least partial… — similarity 0.010
• King-and-pawn endgame with no pieces other than kings and pawns, frequently… — similarity 0.007
• Detects a king on the back rank or 7th rank in rook endgames, often with the… — similarity 0.004

Example puzzles

Below are 1 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle yPJRZ_M — ELO 889, themes: crushing, endgame, exposedKing, 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).