# Death Blossom

The **Death Blossom** technique involves a *stem* cell of N candidates that sees N *petals*, each an Almost Locked Set.

It is developed by extending the Aligned Pair Exclusion technique into an arbitrary sized set of non-aligned cells (see Subset Exclusion), with most of the cells belonging to Almost Locked Sets.

## Contents

## How it works

A Death Blossom consists of a "stem" cell and an Almost Locked Set (or ALS) for each of the stem cell's candidates. The ALS associated with a particular candidate of the stem cell has that number as one of its own candidates, and within the ALS, every cell that has the number as a candidate can see the stem cell. The ALSes can't overlap; i.e., no cell can belong to more than one ALS. Also, there must be at least one number that is a candidate of every ALS, but is not a candidate of the stem cell. Once we've found a Death Blossom, if an outside cell that doesn't belong to one of the ALSes (and isn't the stem cell) can see every cell in each ALS that has a particular number as a candidate, and the number isn't a candidate of the stem cell, then the number can't be a candidate of the outside cell. The workings of the Death Blossom is best explained via an example. This example is a scrambled version of the example at Andrew Stuart's Advanced Sudoku Strategies page. We have a stem cell at - If
**r1c9=1**, then the blue ALS gets reduced to a Naked Triple of 3, 5 and 6 and so**r6c5<>5**. - If
**r1c9=8**, then**r5c9=7**, and the remainder of the yellow ALS gets reduced to a Naked Pair of 1 and 5 and so**r6c5<>5**.
Therefore, we can eliminate 5 from Observe how this is an extension of Aligned Pair Exclusion, whose cells consist of the |

## Note

If the stem cell has exactly two candidates, like the example above, then the same eliminations can be replicated using a ALS-XY-Wing move.