Advanced sets, fish, wings and strong links

Advanced Sudoku constructions

This group scales familiar logic into larger structures. Naked and Hidden Quads restrict four digits to four cells in one house. A Jellyfish is a size-four fish, distributing one candidate across four base rows and four cover columns, or vice versa. These constructions can be difficult to scan, but the proof remains the same set-based accounting used for pairs, triplets, X-Wings and Swordfish.

WXYZ-Wings and WXYZ-Rings use four-cell almost-locked-set logic: restricted common candidates connect the cells and justify eliminations from their shared peers. The remaining guides extend strong-link reasoning through three-link Skyscrapers, String Kites and X-Loops, including grouped forms where several candidates act as one logical node. Accurate house membership, candidate visibility and link direction matter more than the construction’s visual shape; each article breaks those conditions into a verifiable deduction.