The New Sudoku Players' Forum

[999_Springs]

(no, that's not a joke.)

I ended up with this. I don't know what it is.

Code: Select all

/./|./.|...
...|.1.|...
/./|./.|...
---+---+---
...|./.|...
.@.|./.|...
...|./.|...
---+---+---
...|.1.|...
...|./@|...
...|./.|...

1=cell with candidate 1
/=cell without candidate 1
@=bivalue cell 12
r7c2<>1
r8c2<>2
r5c6<>2


It's not thwo techniques off the same strong link because r5c2 doesn't see the strong link.
What technnique is this? It looks like some sort of kraken fish but I cannot tell.

[Mike Barker]

I think it really is two nice loops in one. The inner one is just the ER:
-1- r123c2=1=r2c123 -1- r2c5=1=r7c5 -1- => r7c2<>1

Attach the two bivalues and you get the other two eliminations:
-2-r5c2-1- r123c2=1=r2c123 -1- r2c5=1=r7c5 -1-r8c6-2- => r5c6|r8c2<>2

Note that this isn't a Y-wing, but is similar. A Y-wing is a nice loop with three elements. This is a four element strong grouped nice loop, but eliminations work the same way. For more information on nice loops and variations you can check out the Collection of Solving Techniques.