Active White rook threatening a decisive intrusion — 7th rank penetration or back-rank mate setup.

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

SAE concept sae_20770 fires when active White rook threatening a decisive intrusion — 7th rank penetration or back-rank mate setup.. It appears in 7 of 9,950 Climbchess puzzles (0.1%), spanning ELO 796–1318 (median 870).

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This page documents Active White rook threatening a decisive…, 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:

Active White rook threatening a decisive intrusion — 7th rank penetration or back-rank mate setup.

This pattern fires in 7 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 796 to 1318, with a median rating of 870. 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:

• Rook endgame where White has a positional or material advantage — connected… — similarity 0.250
• Black rook in an active endgame position, often supporting a skewer or… — similarity 0.167
• A white rook or bishop attacks a square on the 2nd rank, which is also… — similarity 0.125
• Black rook actively placed in the opponent's half or mid-board, creating a… — similarity 0.100
• Rook endgame with active rook placement, often involving deflection… — similarity 0.095

Example puzzles

Below are 7 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle y9L7e — ELO 796, themes: deflection, endgame, mate, side to move: White
• Puzzle y9L7e_F — ELO 796, themes: deflection, endgame, mate, side to move: Black
• Puzzle y9L7e_M — ELO 796, themes: deflection, endgame, mate, side to move: White
• Puzzle zzlB3_M — ELO 870, themes: endgame, mate, mateIn2, side to move: White
• Puzzle 023GF — ELO 1318, themes: advancedPawn, crushing, endgame, side to move: White
• Puzzle 023GF_F — ELO 1318, themes: advancedPawn, crushing, endgame, side to move: Black
• Puzzle 023GF_M — ELO 1318, themes: advancedPawn, crushing, endgame, 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).