# A clear example of the solution to the truth-teller problem

Discuss the question below:

Suppose you were in a country where each person was either a truth teller or a liar. (A truth teller always tells the truth, a liar always lies.) What single question could you ask a person that would allow you to detect whether that person was a truth teller or a liar?

https://brainmass.com/computer-science/coding-and-information-theory/theory-computation-truth-lie-teller-example-244674

#### Solution Preview

Suppose that the truth-teller is named A and the liar is named B. You would say to A: If I asked B if you always told the truth, what would he say?

Let us consider the two possible situations.

A is the liar

B is the ...

#### Solution Summary

This solution provides a clear solution, with explanation, of the truth-teller problem.

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