Practise: Forcing Chain
This verified teaching position begins directly with a real Forcing Chain pattern. Follow the chain, inspect the candidates and make the deduction before you continue.
You are at the verified key position. Use a hint to follow the chain link by link when you need support.
How to spot it
Choose a bi-value cell in a dense area, since short chains are easier to verify. Assume the first candidate and follow the forced placements as far as they go, then repeat with the second. Compare the outcomes: a shared conclusion or a contradiction is your result.
Put it to use
Where you will meet it
Expert grids are the only place this pattern regularly decides the solve. Bring your notes.
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