Sudoku technique guide

W-Wing Sudoku Technique

A W-Wing uses two matching pairs connected by a strong link. This guide explains the idea in plain English, when to look for it, and the common mistake to avoid.

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At a glance

Difficulty

Hard

This is where W-Wing normally sits in a human solving path.

Family

Wing techniques

It belongs to the wing techniques group of Sudoku logic.

Main action

Usually remove candidates

Most technique moves reduce notes first. That often reveals a simpler placement afterwards.

What is W-Wing?

A W-Wing uses two matching pairs connected by a strong link.

The important thing is that this is logic, not guessing. You are using the current candidates to prove that a number must either go in one place, or cannot stay in another place.

In SudoSketch, this technique is designed to work with notes and Coach highlighting, so the key cells and removal cells can be shown clearly.

How W-Wing works

Find two cells with the same two candidates.
Find a strong link connecting them through one of those candidates.
Cells that see both pair cells can lose the other candidate.

When to look for it

Look for W-Wing after easier moves have stopped working. First check for naked singles, hidden singles, locked candidates and simple pairs. If those do not move the puzzle forward, this technique may be worth checking.

For learning, do not try to scan for every advanced technique at once. Pick one method, understand the shape, and practise spotting that one pattern.

Common mistake

The matching pair cells are not enough on their own. You also need the strong link.

If you are unsure, rebuild the candidates first. Bad notes create bad logic, and Sudoku will absolutely punish you for it like a tiny spreadsheet goblin.

W-Wing FAQ

What is W-Wing in Sudoku?