Contested central or open-file square where the side to move initiates a forcing exchange sequence.

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

SAE concept sae_33956 fires when contested central or open-file square where the side to move initiates a forcing exchange sequence.. It appears in 6 of 9,950 Climbchess puzzles (0.1%), spanning ELO 808–1570 (median 1570).

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This page documents Contested central or open-file square where the…, 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 central or open-file square where the side to move initiates a forcing exchange sequence.

This pattern fires in 6 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 808 to 1570, with a median rating of 1570. 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:

• Active white knight in or near the centre that is involved in a tactical… — similarity 0.111
• White rook actively placed on an open file or rank, often near the opponent's… — similarity 0.103
• Black knight advanced to ranks 6–8, uncontested by white, in a middlegame or… — similarity 0.034
• Rook actively placed in a mating or forcing configuration, often participating… — similarity 0.028
• A black knight retreating or relocating to a back-rank square under pressure. — similarity 0.025

Example puzzles

Below are 6 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle zx0yA — ELO 808, themes: crushing, discoveredAttack, endgame, side to move: White
• Puzzle zx0yA_F — ELO 808, themes: crushing, discoveredAttack, endgame, side to move: Black
• Puzzle zx0yA_M — ELO 808, themes: crushing, discoveredAttack, endgame, side to move: White
• Puzzle 01Shz — ELO 1570, themes: crushing, endgame, short, side to move: White
• Puzzle 01Shz_F — ELO 1570, themes: crushing, endgame, short, side to move: Black
• Puzzle 01Shz_M — ELO 1570, themes: crushing, endgame, short, 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).