Black pawn on the 6th rank in a king-and-pawn endgame, often a passed or semi-passed pawn in a zugzwang-sensitive position.
SAE concept sae_20387 fires when black pawn on the 6th rank in a king-and-pawn endgame, often a passed or semi-passed pawn in a zugzwang-sensitive position.. It appears in 15 of 9,950 Climbchess puzzles (0.2%), spanning ELO 605–2343 (median 1323).
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This page documents Black pawn on the 6th rank in a king-and-pawn…, 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:
Black pawn on the 6th rank in a king-and-pawn endgame, often a passed or semi-passed pawn in a zugzwang-sensitive position.
This pattern fires in 15 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 605 to 2343, with a median rating of 1323. That distribution tells you whether this is a beginner cue or a master-level subtlety.
Pattern statistics
| Concept ID | sae_20387 |
|---|---|
| Puzzles where it fires | 15 |
| Min ELO | 605 |
| Median ELO | 1323 |
| Max ELO | 2343 |
| Coverage | 0.15% 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 10 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.
- Puzzle yS8nE — ELO 605, themes: crushing, endgame, long, side to move: Black
- Puzzle yS8nE_F — ELO 605, themes: crushing, endgame, long, side to move: White
- Puzzle zZGI0 — ELO 802, themes: crushing, endgame, pawnEndgame, side to move: Black
- Puzzle zZGI0_F — ELO 802, themes: crushing, endgame, pawnEndgame, side to move: White
- Puzzle zN1WI_F — ELO 1118, themes: crushing, defensiveMove, endgame, side to move: Black
- Puzzle zkTZL_M — ELO 1323, themes: crushing, endgame, pawnEndgame, side to move: White
- Puzzle zqazk_F — ELO 1907, themes: crushing, endgame, long, side to move: White
- Puzzle zqazk_M — ELO 1907, themes: crushing, endgame, long, side to move: Black
- Puzzle znZys — ELO 2343, themes: crushing, deflection, endgame, side to move: Black
- Puzzle znZys_F — ELO 2343, themes: crushing, deflection, 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).
Frequently asked
What is SAE concept sae_20387?
Black pawn on the 6th rank in a king-and-pawn endgame, often a passed or semi-passed pawn in a zugzwang-sensitive position. 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 15 tagged puzzles (0.2% of the set), spanning Lichess ELO 605 to 2343 with a median of 1323.
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.