Saturday, March 12, 2011

The Road To Safety

A lone traveler comes upon a fork in the road. One path leads to safety, the other will lead to certain doom. At the fork there are two twin brothers and each guards one of the paths. One always lies and the other always tells the truth — you do not know who is which.

You can only ask one yes/no question to one of the brothers. What should your question be to find the safe path?

This is one form of a well known logical puzzle known as ‘Knights and Knaves’. This particular format was used in the 1986 film Labyrinth.

The puzzle has many variations and in the future I will post one that is annoyingly more complex. For now, let's see what the answer should be for this one.