Rectangle Elimination
Expert
Reference only
A near-Unique-Rectangle pattern where a strong link on one corner forces a contradiction if a second corner (the "wing") holds the shared digit — eliminating it there.
The solver does not attempt this technique, so Smart Hint will never suggest it. It is documented because you may still want to spot it yourself.
- First colour in the chain
- Cells that establish the pattern
- Where the conclusion lands
- Candidate ruled out
How it works
- A1, A5, and E5 form three corners of a near-UR pattern on {3, 5}, spanning two rows, two columns, and two boxes, with column A carrying a strong link on 3 between A1 and A5.
- If E1 (the fourth corner) were 3, A1 would have to be 5 to avoid a UR deadly pattern — but then the column A strong link forces A5 to be 3, which E1 sees, contradiction. So 3 can be eliminated from E1.
- Not yet in GridWits' live solver — a follow-up pass will verify this reasoning carefully enough to wire it in, since a wrong elimination here would be a genuine soundness bug.