Whip
Assumes the target, follows the chain to a cell with no candidate, and rejects the assumption.
How it works on this board
Assuming the target 2 is true leaves the final cell with no candidate
8
5
1
6
1
3
9
8
9
1
4
3
6
1
7
7
6
2
1
8
3
9
1
7
7
1
8
1
5
6
2
9
1
No marks yetPosition 0 / 2