Pointing triple

A worked example

This position comes from SudokuByte’s lesson on the Pointing triple. Gold cells hold the evidence; green cells are the pattern’s ends.

1. Where to look

   Three copies of a digit fill one internal row or column of a box.

   The same box-to-line deduction, with three possible locations rather than two.

2. Read the evidence in this position

   In box 4, all remaining 1 candidates are r6c1, r6c2, r6c3. All are also in row 6.

3. Why the deduction must follow

   box 4 must get its 1 from these cells. Wherever that 1 lands, row 6 already has its one 1. Its other cells outside box 4 therefore cannot contain 1.

4. Apply the result

   Erase 1 from r6c8. The pattern may remove candidates without immediately solving a cell.