Practise: Forcing Chain
One marked cell has two candidates 1/2. Follow each possible choice: which digit reaches the same result in both branches?
This direct drill begins at a real bounded forcing proof. Whether the marked pivot is 1/2, both checked branches lead to 4.
Example 1 of 4
Your turn first
Your turn first
Find the marked pivot with exactly 1/2. What must be checked in both possible cases?
Remember
A Forcing Chain tests every candidate at a marked pivot. When all checked branches reach the same result, that result is forced: 4.
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