Active bishop (either colour) in an endgame with back-rank mating threats or promotion pressure.

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

SAE concept sae_2016 fires when active bishop (either colour) in an endgame with back-rank mating threats or promotion pressure.. It appears in 145 of 9,950 Climbchess puzzles (1.5%), spanning ELO 671–2658 (median 1282).

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This page documents Active bishop (either colour) in an endgame with…, 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 bishop (either colour) in an endgame with back-rank mating threats or promotion pressure.

This pattern fires in 145 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 671 to 2658, with a median rating of 1282. 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 0.069
• Black bishop actively placed in an endgame, often contesting the same diagonal… — similarity 0.062
• Active rook delivering or threatening a decisive mating attack in the endgame… — similarity 0.042
• Detects an active white bishop in a tactical or endgame position, frequently… — similarity 0.040
• Bishop activity in tactical or endgame positions where a bishop is a key… — similarity 0.038

Example puzzles

Below are 10 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle zh89F — ELO 671, themes: backRankMate, endgame, mate, side to move: White
• Puzzle wobNZ_M — ELO 798, themes: advantage, clearance, endgame, side to move: Black
• Puzzle 01xXd — ELO 867, themes: crushing, endgame, fork, side to move: White
• Puzzle zyUPi — ELO 956, themes: crushing, endgame, fork, side to move: White
• Puzzle zzxik_M — ELO 1208, themes: bishopEndgame, crushing, deflection, side to move: Black
• Puzzle zxPKM_F — ELO 1282, themes: advantage, discoveredAttack, endgame, side to move: Black
• Puzzle 01m2g_F — ELO 1494, themes: crushing, endgame, short, side to move: Black
• Puzzle zsFmZ_M — ELO 1655, themes: bishopEndgame, crushing, endgame, side to move: White
• Puzzle ziSr5 — ELO 2058, themes: hookMate, mate, mateIn2, side to move: Black
• Puzzle zjiQj_M — ELO 2250, themes: endgame, long, master, 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).