Contested pawn endgame with advanced passed pawns and opposing kings in close proximity, often featuring zugzwang.

By Climbchess Research · 2026-05-08 · 3 min read · Updated May 8, 2026

SAE concept sae_4175 fires when contested pawn endgame with advanced passed pawns and opposing kings in close proximity, often featuring zugzwang.. It appears in 18 of 9,950 Climbchess puzzles (0.2%), spanning ELO 828–2343 (median 1182).

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This page documents Contested pawn endgame with advanced passed…, 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:

Contested pawn endgame with advanced passed pawns and opposing kings in close proximity, often featuring zugzwang.

This pattern fires in 18 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 828 to 2343, with a median rating of 1182. That distribution tells you whether this is a beginner cue or a master-level subtlety.

Pattern statistics

Related concepts

The five concepts most often co-firing alongside this one (Jaccard similarity over the puzzle co-occurrence graph) are:

• A contested square on the 5th or 6th rank where both sides have attacking… — similarity 0.150
• A knight is trapped or hanging with no safe retreat, making it a target for… — similarity 0.143
• Black pawn on the 6th rank in a king-and-pawn endgame, often a passed or… — similarity 0.100
• A minor piece or pawn is overloaded or under-defended on a contested central… — similarity 0.100
• Pawn endgame with a locked or near-locked pawn structure where zugzwang or a… — similarity 0.098

Example puzzles

Below are 10 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle yhoJZ — ELO 828, themes: crushing, endgame, pawnEndgame, side to move: Black
• Puzzle yhoJZ_F — ELO 828, themes: crushing, endgame, pawnEndgame, side to move: White
• Puzzle zGRe5 — ELO 1007, themes: crushing, endgame, short, side to move: Black
• Puzzle zGRe5_M — ELO 1007, themes: crushing, endgame, short, side to move: Black
• Puzzle zmkRb_F — ELO 1066, themes: attraction, crushing, deflection, side to move: White
• Puzzle xNepc — ELO 1182, themes: crushing, endgame, pawnEndgame, side to move: Black
• Puzzle xNepc_F — ELO 1182, themes: crushing, endgame, pawnEndgame, side to move: White
• Puzzle zx1EE — ELO 1460, themes: crushing, defensiveMove, endgame, side to move: Black
• Puzzle zx1EE_M — ELO 1460, themes: crushing, defensiveMove, 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).