sudokUI › Sudoku techniques › Death Blossom
Death Blossom in sudoku
Cell Forcing Chain through sets · how it fits
A stem cell's candidates each have a separate petal, an almost locked set holding that candidate only in cells seeing the stem; every petal holds Z, which the stem lacks.
Why it works
Whichever digit the stem takes is removed from its petal, which becomes a locked set and must contain Z. So Z is removed from any cell outside the stem and petals that sees every Z in every petal.
How to spot it
Start from a cell with two or three candidates, then hunt nearby for one small set per candidate, all sharing some other digit.
Worked example
Death Blossom: stem r8c9 links each of its candidates to a petal set; whichever digit the stem takes, some petal locks and places 4, so 4 is removed from cells seeing every 4 of all petals. So 4 is removed from r9c2, r9c3.
Practise it on a real puzzle. sudokUI generates a puzzle that needs Death Blossom and takes you straight to the position where it applies. Hints draw the pattern on the board and explain the step.
In a puzzle's rating
Each time the solver needs Death Blossom, the puzzle's difficulty rating grows by 360. Its class is Unfair. It is needed in 1 in 2,400 puzzles that sudokUI generates. How the rating works.