Detects advanced pawn promotion endgames where a passed pawn is on the 6th or 7th rank and both kings are actively contesting the promotion square.
SAE concept sae_20809 fires when detects advanced pawn promotion endgames where a passed pawn is on the 6th or 7th rank and both kings are actively contesting the promotion square.. It appears in 8 of 9,950 Climbchess puzzles (0.1%), spanning ELO 699–1569 (median 1107).
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This page documents Detects advanced pawn promotion endgames where a…, 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 advanced pawn promotion endgames where a passed pawn is on the 6th or 7th rank and both kings are actively contesting the promotion square.
This pattern fires in 8 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 699 to 1569, with a median rating of 1107. That distribution tells you whether this is a beginner cue or a master-level subtlety.
Pattern statistics
| Concept ID | sae_20809 |
|---|---|
| Puzzles where it fires | 8 |
| Min ELO | 699 |
| Median ELO | 1107 |
| Max ELO | 1569 |
| Coverage | 0.08% 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 8 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.
- Puzzle zynHn — ELO 699, themes: advancedPawn, bishopEndgame, crushing, side to move: Black
- Puzzle zynHn_F — ELO 699, themes: advancedPawn, bishopEndgame, crushing, side to move: White
- Puzzle zynHn_M — ELO 699, themes: advancedPawn, bishopEndgame, crushing, side to move: Black
- Puzzle 00L84 — ELO 1107, themes: advancedPawn, crushing, endgame, side to move: White
- Puzzle 00L84_F — ELO 1107, themes: advancedPawn, crushing, endgame, side to move: Black
- Puzzle zdIrD — ELO 1569, themes: advancedPawn, crushing, endgame, side to move: Black
- Puzzle zdIrD_F — ELO 1569, themes: advancedPawn, crushing, endgame, side to move: White
- Puzzle zdIrD_M — ELO 1569, themes: advancedPawn, crushing, 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_20809?
Detects advanced pawn promotion endgames where a passed pawn is on the 6th or 7th rank and both kings are actively contesting the promotion square. 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 8 tagged puzzles (0.1% of the set), spanning Lichess ELO 699 to 1569 with a median of 1107.
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.