Mirrored from Sudopedia, the Free Sudoku Reference Guide
An unavoidable set is a Deadly Pattern from the point of view of a puzzle maker, or somebody who likes to investigate solution grids.
Take the following example:
If there were no givens in any of these 6 cells, the solver would eventually reach a point were a choice must be made how to place digits 1 and 2 in them. The conclusion would be that the puzzle has 2 possible solutions. It is unavoidable for the puzzle maker to place at least one given in one of these cells.
This page was last modified 11:18, 2 November 2006.