Practise: XYZ-Wing
This puzzle is picked so that the easy moves run out and exactly the XYZ-Wing gets you going again. Solve as far as you can — when nothing obvious is left, the pattern is waiting for you.
Skip the obvious cells and start right where the technique is needed.
How to spot it
Find a cell with exactly three candidates and check whether it sees two bi-value cells that each share two digits with it and one with each other. Then look for cells seeing all three, which in practice means the box containing the hinge.
Put it to use
Where you will meet it
Expert grids are the only place this pattern regularly decides the solve. Bring your notes.
Play ExpertStuck on a grid of your own?
Type the position into the solver and it walks the whole solution, naming the technique behind every step — including this one.
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