Skip to content
Frosted Board

Puzzle #40: Dots and Boxes

  • DifficultyHard
  • To moveLight
  • TaskTake 14 of 23
  • Main line27 half-moves

Light to move on the 5 × 5 board. 33 of 60 lines are drawn, Dark has 0 boxes and Light 2.

23 boxes are still unclaimed. With best play you can take 14 of them, 5 more than the opponent gets, and exactly one line achieves that.

What the position is about

  • double-dealing — The key line declines the last boxes of a chain so that the opponent has to open the next one.
  • keep control — With best play you stay in control and collect more than half of what is left.

Finding the way in

On 5×5 the chains are long and the loops expensive. Work out the value of opening each component, and open the cheapest one for the opponent to take.

Play the position in your head from the opponent's side: what would you do against your favourite move? If there is a good answer, try the next candidate.

Show the first move

Start with a5-a6. Played out against the stiffest resistance, the whole line goes: a5-a6 a5-b5 e1-f1 f1-f2 e2-e3 f2-f3 a3-b3 b2-b3 c2-c3 d2-d3 b3-b4 c4-d4 c3-c4 c5-d5 d5-e5 d4-d5 d5-d6 d2-e2 d3-e3 d1-d2 c1-c2 b1-b2 a1-a2 e3-e4 e4-f4 e5-f5 e6-f6.

Solve it and the next puzzle of the same game is one tap away. Your solved puzzles are ticked in the list, in this browser only.