Math Problem of the Month: April 2023

You find yourself on a strange island with three types of people: knights, knaves, and spies. Knights always tell the truth, knaves always lie, and spies (being very sneaky) can either tell the truth or lie. There are three people in front of you—one is a knight, one is a knave, and one is a spy. They know each other’s true identities, but you don’t.

The first one says, “I’m not a spy.”

The second one says, “I am a knave.”

The third one says, “If you asked me, I would say the second one is a spy.”

What are the true identities of each of the three people?

Come to Math Club at 3 PM on Wednesday in Room 3607 to discuss this problem

This article also appears in our April 2023 print edition.