Nice Loop
When an alternating inference chain closes into a loop.
Explanation
A continuous Nice Loop alternates strong and weak links and comes back to its starting candidate. Because the loop is consistent in both directions, every weak link acts like a strong one: the other candidates in a weak-link cell, and the linked digit elsewhere in a weak-link unit, can all be removed.
Practice tip
Start from a bivalue cell or a conjugate pair, alternate strong and weak links, and watch for the chain meeting itself again.
Example steps
- Chain candidates with alternating strong and weak links.
- Close the chain back onto its starting candidate.
- Remove the extra candidates around every weak link of the loop.