Death Blossom
Points.
A Death Blossom consists of a "stem" cell and an Almost Locked Set (ALS)
for each of the stem cell's candidates. The ALS associated with each
candidate of the stem cell has that digit as a candidate, and every
occurrence of that digit in the ALS can see the stem cell. The ALSs can't
overlap i.e., no cell belongs to more than one ALS. Also, each ALS must have
at least one digit that is not in the stem cell. What Sudopedia Says.
Death Blossom Example 1. The
first example is from the Sudopedia website. The stem cell is the vivalue
cell (18)r1c9. It connects to 2 ALS each with 3 cells, one in r5 and
the other in c5. It eliminates the red candidate 5r5c5.
In terms of cover logic, a
death blossom is simply an ALS chain. This example has 7 cell truths
covered by 8 cover links. Two cover links overlap in r6c5 to eliminate
5r5c5.
(See logic diagram below)


Death Blossom Example 1, 3D View. In this 3D view of the Sudopedia example, it's
easy to see that the Death Blossom looks like a chain that has ALS on
either end. This example looks like putting the eye of one needle through
the eye of another needle.


Death Blossom Example 2. The
second example has a stem cell r2c8 with digits 2 and 3, which connect to
two column ALS. The ALS in column 3 is shaded green and the ALS in column 5
is shaded red. Digit 9 in r5c3 sees both and is thus eliminated.


Death Blossom Example 3. The
third example has a stem cell in r1c6 with digits 2 and 9. Each ALS has
only two cells. The ALS in column 4 is shaded red and the ALS in column 6
is shaded green. There are two eliminations, each contained in a different
box/column pair, r3c6 <> 8 and r6c4 <> 8.


Death Blossom Example 4. The
fourth example also has two eliminations but they are different digits. The
stem cell with digits 2 and 5 is in r7c9 and the 2 ALS are in row 5 and
cloumn 6 respectivly. Digits 6 and 8 see all examples of digits 6 and 8 in
both ALS, and are thus eliminated.


Death Blossom Example 5. A
single box/row overlap eliminates two candidates.



Logic Diagram, Death
Blossom Example 1.
(5c5) (6c5) (3c5) (1r1) (8c9) (7r5) (1b5) (5b5)
3N5:
5r3c5==6r3c5==3r3c5
  
7N5:
 6r7c5==3r7c5
 
1N5:
5r1c5=========3r1c5==1r1c5
 
1N9:
 1r1c9==8r1c9
 
5N9:
 8r5c9==7r5c9
 
5N4:
 7r5c4==1r5c4==5r5c4
   
5N6:
 7r5c6==1r5c6==5r5c6
 
2V1:
5r6c5+
