Platon Sudoku · Sudoku Study

At least one in a group · Core Concepts

A region must contain a digit. If its only outside position is false, at least one member of the group is true.

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

Definition

A region must contain a digit. If its only outside position is false, at least one member of the group is true.

List every position for the digit in the region, rule out the outside position, and check for other outside places.

A true group does not mean every member is true. A missed outside candidate breaks the conclusion.

Teaching board · local candidate diagram

Observe candidates

A region must contain a digit. If its only outside position is false, at least one member of the group is true.

Verify the condition

List every position for the digit in the region, rule out the outside position, and check for other outside places.

Draw the conclusion

If the only outside position is false, at least one candidate inside the group must be true.

Teaching board · local candidate diagram

Observe candidates

A region must contain a digit. If its only outside position is false, at least one member of the group is true.

Verify the condition

List every position for the digit in the region, rule out the outside position, and check for other outside places.

Draw the conclusion

If the only outside position is false, at least one candidate inside the group must be true.

Teaching board · local candidate diagram

Observe candidates

A region must contain a digit. If its only outside position is false, at least one member of the group is true.

Verify the condition

List every position for the digit in the region, rule out the outside position, and check for other outside places.

Draw the conclusion

If the only outside position is false, at least one candidate inside the group must be true.

Teaching board · local candidate diagram

Observe candidates

A region must contain a digit. If its only outside position is false, at least one member of the group is true.

Verify the condition

List every position for the digit in the region, rule out the outside position, and check for other outside places.

Draw the conclusion

If the only outside position is false, at least one candidate inside the group must be true.