A black piece controlling a square adjacent to the white king, typically in an endgame mating pattern.
SAE concept sae_26669 fires when a black piece controlling a square adjacent to the white king, typically in an endgame mating pattern.. It appears in 224 of 9,950 Climbchess puzzles (2.3%), spanning ELO 613–2572 (median 1410).
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This page documents A black piece controlling a square adjacent to…, 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:
A black piece controlling a square adjacent to the white king, typically in an endgame mating pattern.
This pattern fires in 224 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 613 to 2572, with a median rating of 1410. That distribution tells you whether this is a beginner cue or a master-level subtlety.
Pattern statistics
| Concept ID | sae_26669 |
|---|---|
| Puzzles where it fires | 224 |
| Min ELO | 613 |
| Median ELO | 1410 |
| Max ELO | 2572 |
| Coverage | 2.25% 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 xbPL4 — ELO 613, themes: anastasiaMate, endgame, mate, side to move: White
- Puzzle RM6z0 — ELO 801, themes: advantage, interference, middlegame, side to move: Black
- Puzzle nhl5u_F — ELO 897, themes: advantage, interference, middlegame, side to move: White
- Puzzle zwkR0_F — ELO 1055, themes: clearance, deflection, kingsideAttack, side to move: White
- Puzzle zy3ZS_M — ELO 1195, themes: advantage, endgame, pin, side to move: White
- Puzzle zz0Qh_M — ELO 1410, themes: crushing, fork, middlegame, side to move: Black
- Puzzle zv6eP_M — ELO 1642, themes: endgame, mate, mateIn1, side to move: White
- Puzzle zgVvD_F — ELO 1819, themes: advantage, middlegame, short, side to move: Black
- Puzzle zfacu_M — ELO 2171, themes: discoveredAttack, discoveredCheck, exposedKing, side to move: White
- Puzzle zp3Hc — ELO 2404, themes: crushing, endgame, long, 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_26669?
A black piece controlling a square adjacent to the white king, typically in an endgame mating pattern. 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 224 tagged puzzles (2.3% of the set), spanning Lichess ELO 613 to 2572 with a median of 1410.
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.