GridWits
Medium tier Technique 13 of 31 Used by Smart Hint

Border Clue and Dot

One clue combines with a nearby border dot, whose missing outside edge reduces its possibilities.

How it works

  1. 1The 2 is in the top-left cell. Look one dot to its right, on the top border, where only three edges can meet.
  2. 2Try the two possible states of the clue's top edge while keeping the clue at exactly two lines and that border dot at zero or two.
  3. 3Both possibilities need the top edge immediately to the right of the clue, so draw it. No second clue is part of this proof.
2
  • Edge the technique adds
  • Cells that establish the pattern
Next in the ladder Adjacent 3s →

Two 3s side by side: the outer edge of each one — the side facing away from its partner — is always a line.