Detects a king-and-pawn zugzwang endgame where king opposition relative to a passed pawn determines whether the pawn successfully promotes.
SAE concept sae_35409 fires when detects a king-and-pawn zugzwang endgame where king opposition relative to a passed pawn determines whether the pawn successfully promotes.. It appears in 6 of 9,950 Climbchess puzzles (0.1%), spanning ELO 763–963 (median 963).
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This page documents Detects a king-and-pawn zugzwang endgame where…, 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:
Detects a king-and-pawn zugzwang endgame where king opposition relative to a passed pawn determines whether the pawn successfully promotes.
This pattern fires in 6 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 763 to 963, with a median rating of 963. That distribution tells you whether this is a beginner cue or a master-level subtlety.
Pattern statistics
| Concept ID | sae_35409 |
|---|---|
| Puzzles where it fires | 6 |
| Min ELO | 763 |
| Median ELO | 963 |
| Max ELO | 963 |
| Coverage | 0.06% of puzzle set |
Related concepts
The five concepts most often co-firing alongside this one (Jaccard similarity over the puzzle co-occurrence graph) are:
Example puzzles
Below are 6 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.
- Puzzle zDwOn — ELO 763, themes: crushing, defensiveMove, endgame, side to move: White
- Puzzle zDwOn_F — ELO 763, themes: crushing, defensiveMove, endgame, side to move: Black
- Puzzle zDwOn_M — ELO 763, themes: crushing, defensiveMove, endgame, side to move: White
- Puzzle ztS51 — ELO 963, themes: crushing, defensiveMove, endgame, side to move: Black
- Puzzle ztS51_F — ELO 963, themes: crushing, defensiveMove, endgame, side to move: White
- Puzzle ztS51_M — ELO 963, themes: crushing, defensiveMove, endgame, 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).
Frequently asked
What is SAE concept sae_35409?
Detects a king-and-pawn zugzwang endgame where king opposition relative to a passed pawn determines whether the pawn successfully promotes. It is one of 4,505 interpretable features extracted from Leela Chess Zero's residual stream via sparse autoencoders, then labelled by reading the top-activating positions.
Where does this pattern appear?
In 6 tagged puzzles (0.1% of the set), spanning Lichess ELO 763 to 963 with a median of 963.
How do I train it?
Open the Climbchess trainer and filter for puzzles tagged with this concept. The trainer adapts difficulty using your live recognition profile and tracks how often you spot the cue versus miss it.
Is it free?
Yes. Climbchess is free forever, with no account, email, or signup required. You can delete your data at any time.