It is not necessary in Mrrzy's original problem to assume additionally that only 'yes' or 'no' are allowed as responses. You walk to either of them and ask: "If I ask your brother where this door leads to what will he respond?" If I get the response "To Hell" I walk through this door, if I get the response "To Heaven" I take the other door. So the problem as stated by Mrrzy was complete for all practical purposes.

Wolfgang