# Is this a correct solution to determining which of two people is the liar using one question?

I am a newbie to Stack-Exchange and if there is any problem in my question -- I apologize beforehand .

I was working my way through some Propositional Logic Questions in Discrete Maths by Rosen , when I came across the following question :

An explorer is captured by a group of cannibals. There are two types of cannibals—those who always tell the truth and those who always lie. The cannibals will barbecue the explorer unless he can determine whether a particular cannibal always lies or always tells the truth. He is allowed to ask the cannibal exactly one question.

Find a question that the explorer can use to determine whether the cannibal always lies or always tells the truth.

My Solution :

If I were to ask you whether you are a liar, would you answer yes?

• The honest person would say NO.
• The liar would say YES (due to double negation).

Doubt :

Am I correct in saying my answer will work? It almost seems too simple.

• Thanks @Thumbnail - how do we do the greying area thing ? – pranav Dec 23 '14 at 16:46
• It's hinted block quote. – Thumbnail Dec 23 '14 at 17:27
• If you're patient enough you can watch this video, otherwise you can read this dialog... – Pierre-Yves Gaillard Jun 20 '17 at 19:36
• I would ask "is 1 plus 1 equal to 2?" Liar "no", honest person "yes" – miracle173 Jun 20 '17 at 19:41