Practise: Empty Rectangle
This verified teaching position begins directly with a real Empty Rectangle pattern. Follow the chain, inspect the candidates and make the deduction before you continue.
You are at the verified key position. Use a hint to follow the chain link by link when you need support.
How to spot it
Scan boxes for a digit whose candidates avoid one 2×2 corner entirely, so they form an L or cross shape. Then find a row or column outside the box where the digit has exactly two candidates, one of which aligns with the box's row or column. The elimination sits where the remaining candidate's line crosses the box's other line.
Put it to use
Where you will meet it
Expert grids are the only place this pattern regularly decides the solve. Bring your notes.
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