Pointing Triples Sudoku Technique
Pointing triples are an advanced Sudoku solving technique that builds on the logic of pointing pairs. This strategy is especially useful for intermediate and advanced players who want to tackle more challenging puzzles and eliminate candidates with greater precision.
What is a Pointing Triple?
A pointing triple occurs when, within a 3x3 box, a candidate number appears only in three cells, all of which are aligned in a single row or a single column of that box. This means the candidate must be placed in that row or column within the box, so it cannot appear elsewhere in the same row or column outside the box.
Example:
- In a box, the candidate 5 appears only in three cells, all in the same column.
- This means 5 must be placed in that column within the box.
- Therefore, you can eliminate 5 as a candidate from the rest of that column outside the box.
How to Spot Pointing Triples
- Examine each 3x3 box for candidate numbers that are limited to three cells, all in the same row or column within the box.
- Look at the rest of that row or column outside the box for the same candidate.
- Eliminate the candidate from those cells outside the box, as it must be placed within the box in that row or column.
Why Pointing Triples Work
If a candidate is restricted to three cells in a single row or column within a box, Sudoku rules dictate that the candidate must be placed in one of those cells. Any other occurrence of that candidate in the same row or column (but outside the box) would violate the rule that each number appears only once per row, column, and box.
Example of a Pointing Triple
Imagine in the middle 3x3 box, the candidate 7 appears only in three cells, all in the middle row of that box. This means 7 must be placed in one of those three cells. As a result, you can eliminate 7 as a candidate from the rest of the middle row outside that box.
Visual Example Coming Soon
Practice and Tips
- Use pencil marks (candidate notation) to spot pointing triples more easily.
- Pointing triples are less common than pointing pairs, but can be crucial in difficult puzzles.
- Combine pointing triples with other techniques like naked triples, box-line reduction, and hidden singles for maximum solving power.
Summary
Pointing triples are a powerful but often overlooked technique for eliminating candidates and making progress in tough Sudoku puzzles. By mastering this strategy, you can solve more challenging puzzles with confidence.
Ready to practice? Try our Sudoku puzzles and put pointing triples to use!