Proven Sudoku
Techniques / Almost locked sets
Aligned Triple Exclusion
Also called ATE.
New to this shorthand? How to read a sudoku grid explains r4c7, houses, candidates and the rest.
What it means
Look at three squares together and list every set of three numbers they could hold. Cross out the sets blocked by their neighbours. If a number never survives, it can go.
The exact rule, for stronger players
The rule, stated exactly: Aligned Pair Exclusion extended to three mutually visible cells.
What it removes: Remove candidates appearing in no surviving triple.
Why it works: As for APE, over triples instead of pairs.
Worked examples
None yet. This pattern does not turn up in our daily boards, so there is no real example to show. We would rather wait than draw a fake one.
Learn these first
- Aligned Pair ExclusionLook at two squares together and list every pair of digits they could hold.
Related almost-locked sets
- Almost Hidden SetThe mirror image of an almost locked set.
- Almost Locked CandidatesTwo areas cross.
- Almost Locked SetA small group of squares holding exactly one number more than there are squares.
- ALS ChainA row of almost full groups linked one to the next.
- ALS-XY-WingThree almost full groups arranged like a wing.
How often does it come up?
Our rough estimate: rare, and impractical by hand.