Platon Sudoku · Sudoku Study

Deadly rectangles · Core Concepts

Four cells in two rows, columns and boxes, each with only the same pair, could swap that pair and create a second completion.

This course is adapted from Platon Sudoku App. Read the complete example here, then continue learning and practising in the app.

Definition

Four cells in two rows, columns and boxes, each with only the same pair, could swap that pair and create a second completion.

Check the four corners, exactly two boxes, and the same two candidates in all four cells.

The cells must span exactly two boxes and each have only the same pair. Four boxes or an extra candidate breaks the condition.

Teaching board · local candidate diagram

Observe candidates

Four cells in two rows, columns and boxes, each with only the same pair, could swap that pair and create a second completion.

Verify the condition

Check the four corners, exactly two boxes, and the same two candidates in all four cells.

Draw the conclusion

Four cells span two rows, columns, and boxes with the same candidate pair.

Teaching board · local candidate diagram

Observe candidates

Four cells in two rows, columns and boxes, each with only the same pair, could swap that pair and create a second completion.

Verify the condition

Check the four corners, exactly two boxes, and the same two candidates in all four cells.

Draw the conclusion

Four cells span two rows, columns, and boxes with the same candidate pair.