Death Blossom
A "stem" cell's candidates are each matched to their own Almost Locked Set (a "petal") — a digit common to every petal can be eliminated from any cell all the petals can see.
The solver does not attempt this technique, so Smart Hint will never suggest it. It is documented because you may still want to spot it yourself.
How it works
- 1A1 is the stem, {3, 6}. Its 3 opens the petal D1 + D2, an Almost Locked Set on {3, 7, 9}; its 6 opens the petal A5, the bivalue {6, 9}.
- 2Each petal keeps its copy of the stem digit where the stem can see it: D1 shares row 1 with A1, A5 shares column A.
- 3If A1 is 3, D1 loses its 3 and that petal locks onto {7, 9}, so its 9 gets used. If A1 is 6, A5 loses its 6 and must be 9. Either way a 9 is tied up inside one of the petals.
- 4D5 sees every 9 in both — D1 and D2 down column D, A5 across row 5 — so its own 9 can go.
- First colour in the chain
- Second colour in the chain
- Cells that establish the pattern
- Where the conclusion lands
- Candidate ruled out