Sudoku Strategy Y Wing

One of the more complex sudoku strategies is the x wing and its cousin the swordfish.

Sudoku strategy y wing. The forth corner is where the candidate can be removed but it leads us to much more as we ll see in a minute. This square is sometimes called a pivot or hinge. The cell in the center is called the pivot. These rules are useful for solving the really difficult sudoku puzzles when all else has been tried and failed.

X wing extends to swordfish and jellyfish while y wing brings a nice set of other rules which we will examine in later articles. The name derives from the fact that it looks like an x wing but with three corners not four. Y wing is a strategy that allows you to eliminate candidates. Xy wing involves 3 different cells each with exactly two candidates pencil marks that are related to each other in such a way that you can make some logical conclusions.

Sudoku dragon daily online help manual introduction sudoku history strategy advanced theory guessing symmetry variants guides guessing symmetry hook or x y wing sudoku puzzle solving guide step. As a last resort for solving really difficult puzzles when you have tried everything else the hook. Y wing example 1. The red square in the above image is the pivot.

This is an excellent candidate eliminator and is also known as xy wing. An xy wing is a solving technique that uses a short chain of 3 cells. We take a look at this extremely powerful and important technique which comes up again and again in difficult puzzles. The other 2 cells are the pincers.

From the start i have found a superb tough sudoku puzzle with a sequence of five y wings and this illustrates the full range of this strategy. This is a tad specific for my taste. You can use y wing if each of the two candidates in the pivot forms a conjugate pair in two. Most techniques tips tricks about how to solve sudoku puzzles stop before they generalize ideas.

In looking for twins and permutations we restricted ourselves to looking at possibilities within a single group. Probably best just to show you. Below is an example of an xy wing. Load example or.

Let s look at figure 19 1 for the theory. Sudoku app learn hard y wing. The first three are pictured here but you can load the puzzle into the solver to see the remaining examples. A y wing considers strength in cells to deduce strength in candidate location.

Y wing starts with a square that contains exactly two candidates. Note how the 3 cells form a y see the red lines it s really more like a v.