Expert Sudoku

Three eliminations, not one

Expert puzzles require at least three elimination steps and still no advanced pattern. The givens run from 26 to 34, but the count is not what makes them hard — the chaining is.

On Hard, one deduction reopens the grid. On Expert the grid closes again almost immediately, and you need a second and a third deduction before placements resume. Solving one is less about spotting a pattern and more about not losing the thread between them.

Subsets get bigger

This is where triples and quads appear. A naked triple is three cells in a unit sharing three candidates between them — no cell needs all three, they just cannot hold anything else. A hidden triple is the same relationship read backwards: three digits that can only live in three cells, which lets you strip every other candidate from those cells.

Hidden subsets are the ones players miss, because nothing about the cells looks unusual until you count where each digit can still go.

Keeping notes honest

• Fill candidates for the whole grid, not one unit — partial marks hide subsets.
• Erase a candidate the moment a placement kills it, or you will trust a stale grid.
• After each elimination, re-scan for singles before hunting for the next pattern.
• If two units both look promising, work the one with fewer empty cells first.

The last level before advanced patterns

Expert is the ceiling you can reach with unit-local logic: everything you need is inside a single row, column or box. Master and Extreme break that boundary, and the techniques there compare cells that share no unit at all.