Math · Exploration
The Hardest Logic Puzzle Ever
Find True, False, and Random in just three questions.
Three gods, two unknowns
A, B, and C are, in some order, True, False, and Random. True always speaks truly; False always lies; Random answers according to an internal coin flip. They answer only ja or da, and you do not know which means yes.
Play the puzzle
Ask a god
Choose the inner question
Possible worlds
Make your identification
The useful device
The outer question—If I asked you Q, would you say ja?
—cancels two uncertainties at once: whether a reliable god is truthful or false, and which word means yes. For a non-Random god, ja then means that Q is true.
What makes it hard
The challenge is not merely distinguishing truth from lies. Your first move must also protect you from Random, whose answer gives no dependable information. Watch the possible worlds: a good question preserves a route to a god who is definitely not Random.