You may also like
Yih or Luk Tsut K'i or Three Men's Morris
Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots and a little about prime knots, crossing numbers and knot arithmetic.
Age 11 to 14
Challenge Level
Khun Phaen is a famous character in Thai Legend. This game was originally known as `Khun Chang Khun Phaen' and refers to Khun Phaen being imprisoned. He breaks out of jail by escaping the cordon of nine sentries who are guarding him.
The jail is represented by a four by five rectangle as shown. Starting with the square representing Khun Phaen and the rectangles and squares A, B, C, D, E, F, G, H, I, representing the guards in the positions shown in the diagram, you have to slide the pieces, keeping them all inside the jail at all times, to move Khun Phaen past all the guards into the position at the centre bottom from which he can escape to freedom.
The best way to try this challenge is to make yourself a model in cardboard or wood with a rectangular frame to keep all the pieces within bounds.
Khun Phaen - Ten More Challenges
NRICH is part of the family of activities in the Millennium Mathematics Project.