# Subset Exclusion

The nameSubset Exclusionis not commonly used in the Sudoku community. This article is created as a bridge betweenAligned Pair ExclusionandDeath Blossom.

**Aligned Pair Exclusion** can be extended to **Aligned Triple Exclusion** and so on. In fact, the set of cells to be enumerated does not need to be aligned at all. Lacking a better name, let us call the resultant technique **Subset Exclusion**.

## Example

We can enumerate the possible combinations of the blue cells as in Aligned Pair Exclusion. The following list shows the possible combinations, from top to bottom: 5+2+4 5+2+6 5+6+4 5+7+4* 5+7+6* 5+9+4* 5+9+6* 7+2+4 7+2+6 7+6+4 7+9+4 7+9+6 The starred combinations are those that causes any of the yellow cells to have no candidates at all, so these combinations can be removed from the list. As a result, we find that 7 can be eliminated from |

## Death Blossom

The **Death Blossom** technique is actually an instance of **Subset Exclusion** where all but one of the cells to be enumerated falls neatly into Almost Locked Sets.