GridWits
Extreme tier Technique 31 of 31 Used by Smart Hint

X-Cycles

An X-Chain closed into a loop. Closure is what upgrades it: the loop can eliminate along every weak link, or settle one cell outright.

How it works

  1. 1Build the same single-digit chain of strong and weak links as X-Chain, but bring it back to where it started.
  2. 2An EVEN loop that alternates perfectly is continuous: every weak link in it has exactly one end on. Any cell outside the loop that sees both ends of one of those weak links cannot be the digit.
  3. 3An ODD loop has one node where the alternation breaks, and that node is the whole conclusion.
  4. 4If the defect node carries two STRONG links, it MUST be the digit — the only rule here that places rather than eliminates.
  5. 5If it carries two WEAK links, it cannot be the digit at all.