Forcing Chain
AdvancedUsed at: Master
An advanced technique using hypothetical chains. Starting from a cell's candidates, reasoning is carried forward step by step.
Forcing Chain Steps
1
Pick a starting cell
Choose a cell with two candidates and assume one of them.
2
Follow the chain
Apply basic techniques to see where the assumption leads.
3
Check the result
If a contradiction occurs, the other candidate is correct. If not, find common cells across both chains.