Expert sudoku
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Expert sudoku: fish and wings
Expert grids need patterns that span several rows, columns and boxes at once. They start like any other grid, then stall: the singles, pairs and triples run out, and only a fish or a wing moves things on.
What it takes
Fish (the X-wing, swordfish and jellyfish) look at where one digit can go across two, three or four rows. Wings and single-digit patterns, like the XY-wing or the skyscraper, link a few cells so that, whichever way they turn out, some candidate is ruled out. Quads are pairs and triples with four digits.
And everything from Easy, Medium, and Hard.
How long it takes
Thirty minutes to an hour is common, even for regular players.
Tips
- Keep your notes complete and correct: one wrong note can hide an X-wing for good.
- For fish, pick one digit and look at its notes only: rows where it fits in exactly two places are where to start.
- Cells with exactly two candidates are what wings are built from.
- The weekend daily is an expert grid: a good weekly challenge.
Questions
What is an X-wing in sudoku?
A digit that fits in exactly two places in each of two rows, in the same two columns. One of each pair must be the digit, so the rest of those two columns can’t have it. The X-wing lesson shows one on a real grid.
Can expert sudoku be solved without guessing?
Yes. Every expert grid here is graded by the techniques it needs, and solved by logic alone.
What comes after expert?
Master: grids that need chains and coloring, the most advanced logical steps.