A critical 3rd-rank (White) or 6th-rank (Black) square in a king-and-pawn endgame, often key to zugzwang or a pawn breakthrough.

By · · 3 min read · Updated May 8, 2026

SAE concept sae_31719 fires when a critical 3rd-rank (White) or 6th-rank (Black) square in a king-and-pawn endgame, often key to zugzwang or a pawn breakthrough.. It appears in 29 of 9,950 Climbchess puzzles (0.3%), spanning ELO 1118–2652 (median 1681).

Free forever 4,505 patterns 9,950 puzzles 20 languages
Try Climbchess free — no signup, no email

Free forever · no email · no signup · delete data anytime.

This page documents A critical 3rd-rank (White) or 6th-rank (Black)…, 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 critical 3rd-rank (White) or 6th-rank (Black) square in a king-and-pawn endgame, often key to zugzwang or a pawn breakthrough.

This pattern fires in 29 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 1118 to 2652, with a median rating of 1681. That distribution tells you whether this is a beginner cue or a master-level subtlety.

Pattern statistics

Concept IDsae_31719
Puzzles where it fires29
Min ELO1118
Median ELO1681
Max ELO2652
Coverage0.29% 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.

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_31719?

A critical 3rd-rank (White) or 6th-rank (Black) square in a king-and-pawn endgame, often key to zugzwang or a pawn breakthrough. 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 29 tagged puzzles (0.3% of the set), spanning Lichess ELO 1118 to 2652 with a median of 1681.

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.