Quote:


If the head imparting this important information is telling the truth, the scenario can play out substantially as you have set forth.

But what if the head giving this rule is the liar? If so, everything thereafter is indeterminate.



I know. You seemed to have "skip-read" the following portion of my post:

Quote:

Sarah's formulation is the correct solution to the scenario described by the Blue Guard ("One of us always tells the truth, and one of us always lies"); however, she overlooked the possibility that the Blue Guard, when he explained this rule, was lying. If the Blue Guard were lying, other scenarios are possible. In some of these, her formulation is useless—such as one in which all four guards lie and tell the truth inconsistently, and both doors lead to certain death.


The poster formerly known as Hydra.