The corner clue: in a corner of the room, or not

What the clue says

The person stood in a cell that has a wall of their own room on two sides that meet: top and left, top and right, bottom and left, or bottom and right. The edge of the board counts as a wall. In an L-shaped room the cell inside the bend also has two walls that meet, so it is a corner as well.

What it rules out

Cells in the middle of a room, and cells along a single wall. A rectangle has four corners. A 2×2 room is all corners. A room one cell wide has corners only at its ends, because the middle cells have walls on opposite sides, which do not meet. A one-cell room is a corner too.

So the clue is strongest on big open rooms and weakest on small ones. Check every room, not just the one that looks like it has corners.

The negative form

"She was not in a corner of the room." Cross out every corner cell for her, in every room. On a board of small rooms that can remove most of the board; on a board of large rooms it removes only a handful. Small rooms with only corner cells disappear for her entirely.

Common mistakes

• Looking only at the board's corners. Every room has its own corners.
• Missing inner corners. Where a room bends, the cell in the bend is a corner.
• Counting the middle of a narrow strip. Walls on opposite sides do not make a corner.
• Forgetting scenery. A table in a corner blocks the cell, so that corner is gone.

How it combines with other clues

Corner plus a room clue usually leaves two to four cells. Corner plus a line clue often leaves one. Corner plus on an object picks the seat in a corner. When a line has a single corner cell that only one person can use, that person must take it, which is the idea of the technique the only one who fits.