Hook mate pattern: rook-and-knight cooperation delivering mate to a cornered king, with a passed pawn or key square restriction involved.

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

SAE concept sae_27874 fires when hook mate pattern: rook-and-knight cooperation delivering mate to a cornered king, with a passed pawn or key square restriction involved.. It appears in 3 of 9,950 Climbchess puzzles (0.0%), spanning ELO 2170–2170 (median 2170).

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This page documents Hook mate pattern: rook-and-knight cooperation…, 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:

Hook mate pattern: rook-and-knight cooperation delivering mate to a cornered king, with a passed pawn or key square restriction involved.

This pattern fires in 3 of our 9,950 tagged puzzles. The puzzles where it appears span ELO 2170 to 2170, with a median rating of 2170. 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 pawn on any rank is under pressure from an enemy rook, often in a deflection… — similarity 0.333
• White rook in a dominant or active position, not under immediate attack by… — similarity 0.100
• Detects an active black bishop in an endgame, typically on a central or… — similarity 0.025
• A white rook is active on an open file or rank, threatening or delivering a… — similarity 0.022
• Black bishop actively placed in an endgame, often contesting the same diagonal… — similarity 0.012

Example puzzles

Below are 3 puzzles spanning the rating distribution. Each links to its own page with full move list and related concepts.

• Puzzle oWqyI — ELO 2170, themes: endgame, hookMate, mate, side to move: White
• Puzzle oWqyI_F — ELO 2170, themes: endgame, hookMate, mate, side to move: Black
• Puzzle oWqyI_M — ELO 2170, themes: endgame, hookMate, mate, 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).