WXYZ-Wing

Level 9 · Purple Belt

Strategy:

Requires:

Overview

WXYZ-Wing uses four cells with candidates forming a restricted pattern. When properly configured, a common candidate can be eliminated from cells seeing all pattern cells.

How It Works

Find four cells whose combined candidates use exactly four digits {W,X,Y,Z}.
One cell (pivot) sees the other three.
Eliminate the restricted digit from cells seeing all four pattern cells.

Example

Starting position

Look for WXYZ-Wing.

Sudoku grid showing the initial puzzle state for Look for WXYZ-Wing.

1

Find the pivot cell r1c3

Find a pivot cell r1c3 with candidates connected to a 3-cell wing group.

Sudoku grid illustrating step 1: Find the pivot cell r1c3 — Find a pivot cell r1c3 with candidates connected to a 3-cell wing group.

2

Wing cells form an ALS with the pivot

The wing cells r5c1, r5c3 and r5c7 form an Almost Locked Set with the pivot.

Sudoku grid illustrating step 2: Wing cells form an ALS with the pivot — The wing cells r5c1, r5c3 and r5c7 form an Almost Locked Set with the pivot.

3

Why the WXYZ-Wing works

This is a WXYZ-Wing - the shared candidate is eliminated from common peers.

Sudoku grid illustrating step 3: Why the WXYZ-Wing works — This is a WXYZ-Wing - the shared candidate is eliminated from common peers.

4

Remove 1 from cells seeing all four

One of the four pattern cells must contain 1, so remove it from cells seeing all four: r4c3.

Sudoku grid illustrating step 4: Remove 1 from cells seeing all four — One of the four pattern cells must contain 1, so remove it from cells seeing all four: r4c3.

5

Result

Result after applying the technique.

Sudoku grid showing the result after applying the technique

Tips & Patterns

WXYZ-Wings have complex requirements - study examples carefully.
They extend the Wing family pattern to four cells.
These are quite rare in most puzzles.