Set Equivalence Theory
(Redirected from SET)
Set Equivalence Theory (commonly abbreviated to SET, sometimes redundantly SET Theory) is an advanced sudoku solving technique. It states that if any set of cells 𝐴 is known to contain the same collection of digits as any set of cells 𝐵, then the set difference 𝐴 \ 𝐵 must also contain the same collection of digits as the set difference 𝐵 \ 𝐴. Usually 𝐴 and 𝐵 are chosen to be some union of non-overlapping rows, columns, and 3×3 boxes, meaning that they are known to contain an equal number of every possible digit.