Info for Students » Uncategorized

Ask Dr. Knowledge: How do you get out of a corn maze?

Q. I just saw a news item about a family getting lost in a corn maze. If this were to happen to me, is there any guaranteed way for me to get out without calling for help? Do I have to have left some sort of trail to follow back out?A. Leaving a trail of dropped objects, or pulling along a thread as the mythological Theseus did in the minotaur’s maze will certainly work. If you didn’t mark out your path, you’re not out of luck though.If the maze is made with walls that — although splitting and turning arbitrarily — are all connected to the outside wall, there’s a very simple way to find a way out, or “traverse” the maze. It’s called the “wall follower” technique. What you do is pick a hand (right or left, either is fine) and put it against a wall. Then start walking and just make sure you never take your hand off the wall. You’ll eventually get out. If you sketch a maze of this sort it will probably be easy to see why it works.A more complicated maze has walls or collections of walls joined together that are like islands in the maze and not connected to the outside wall. The “wall follower” method won’t work if you start at a wall not connected to the outside wall — you’ll wind up walking around the island-like section endlessly. (If you use the technique right from the entrance you will be starting at an outside wall, and will get out fine.)If you’re lost inside, however, you need something more clever. In this case you can use the “Pledge algorithm”, named after John Pledge of Exeter, England, who came up with it when he was just 12 years old! It works for any maze, starting from anywhere. Start walking as you would using the “wall follower” method, but pick an initial direction as “forward” and keep track of how much you’ve turned left or right as you go. Whenever you wind up facing the same direction you started in (say from four lefts; or a left and a right; or left, right, left, right, and so on, assuming the maze has right angles only) stop following the wall and continue going straight until you can start following the wall again. This ensures that you never get stuck going around and around (again a sketch of a maze will help convince you this works). Since you won’t get stuck going in circles, you will eventually get out.E-mail questions to or write to Dr. Knowledge, c/o The Boston Globe, P.O. Box 55819, Boston, MA 02205-5819.

Comments are closed.