Sue de Coq

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Sue de Coq

What It Is

Sue de Coq works at a box-line intersection with N cells holding N+1 candidates. Partition those candidates between the intersection and the remaining cells in the line/box; candidates outside the partition are eliminated.

When to Use

Expert stage with a busy intersection of a row/column and a box where candidates cluster meaningfully.

How to Apply (Step-by-Step)

  1. Identify the box-line intersection and list its candidates (an ALS: N cells, N+1 candidates).
  2. List candidates in the rest of the line and rest of the box.
  3. Partition candidates: split so intersection candidates pair with exclusive sets in line and box.
  4. Eliminate any candidate in the intersection area not part of the partition; place if only one fits.
  5. Re-check for new singles after cleanup.

Intersection cells sharing {1,2,3,4} with row holding {1,3} and box holding {2,4} lock the split—eliminate other occurrences accordingly.

See also

Scanning / Cross-Hatching Single Candidate (Naked Single) Single Position (Hidden Single) Naked Pairs / Triples / Quads Hidden Pairs / Triples / Quads Pointing Pairs / Triples (Locked Candidates Type 1) Box–Line Reduction (Locked Candidates Type 2) X-Wing Swordfish Jellyfish XY-Wing XYZ-Wing W-Wing Alternating Inference Chains (AICs) Forcing Chains / Forcing Nets Nishio Coloring Multi-Coloring Uniqueness Techniques (Unique Rectangle etc.) Fish Variants (Finned X-Wing, Sashimi etc.) ALS Techniques (ALS-XZ, ALS Chains) Sue de Coq Pattern Overlay / Template Method
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