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Multiple Empty Rectangles

Points. Short chain like single digit methods with multiple box end sets are sometimes called multiple empty triangles Below are two examples.

Double Empty Rectangle. The example to the right is sometimes called a double empty rectangle because it uses a second box. In reality, this is more like an X-Cycle that forms a continuous loop. The three truths are covered by three cover links making the logic rank 0.
Triple Empty Rectangle. This example uses 3 box truths and 4 links to form a short one-digit chain that eliminates the digit 3 in r2c7. This logic is rank 1 so anywhere two covers overlap can eliminate candidates.