polysemantic

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

SAE concept sae_26921 fires when polysemantic. It appears in 32 of 9,950 Climbchess puzzles (0.3%), spanning ELO 610–2648 (median 1529).

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This page documents polysemantic, 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:

polysemantic

This pattern fires in 32 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 610 to 2648, with a median rating of 1529. 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:

• This feature detects a square attacked by a single black piece, which is not… — similarity 0.063
• The feature detects a king on the target square that is attacked by at least… — similarity 0.057
• Black king in an active endgame role, often contesting key squares or… — similarity 0.047
• A black rook on or near the back rank that is loosely placed, often in… — similarity 0.045
• A queen (colour unspecified) in a tactically vulnerable position, often near… — similarity 0.041

Example puzzles

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

• Puzzle ydABK — ELO 610, themes: crushing, endgame, hangingPiece, side to move: White
• Puzzle zaLk1_M — ELO 843, themes: crushing, endgame, master, side to move: White
• Puzzle zy1nq — ELO 882, themes: crushing, endgame, fork, side to move: Black
• Puzzle zsQsJ — ELO 1162, themes: advantage, endgame, long, side to move: White
• Puzzle 01eqy_F — ELO 1442, themes: mate, mateIn2, middlegame, side to move: Black
• Puzzle 01kWV — ELO 1529, themes: advantage, deflection, endgame, side to move: Black
• Puzzle zwmT4_M — ELO 1618, themes: advantage, discoveredAttack, discoveredCheck, side to move: White
• Puzzle Mhro9_M — ELO 2120, themes: discoveredAttack, discoveredCheck, endgame, side to move: Black
• Puzzle zx9W6_M — ELO 2147, themes: crushing, endgame, hangingPiece, side to move: Black
• Puzzle zqQ1T_F — ELO 2259, themes: crushing, discoveredAttack, discoveredCheck, 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).