Ok, super simple problem, but it would be good as an example for introducing people to truth tables at the start of a section with a bunch of the “liar” problems.
Problem #1 page 6 of hard-to-solve brainteasers
Problem: Peter and Paul are twins. One of them, we don’t know which, always lies. The other always tells the truth. I ask one of them “Is Paul the one that lies?” and he answers “Yes”. Was I speaking to Peter or Paul?
