Three gods A, B, and C are called, in some order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking minimum number of yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language in which the words for 'yes' and 'no' are 'da' and 'ja', in some order. You do not know which word means which. What is the minimum number of questions required to determine their identities?
This problem was devised by famous logician George Boolos...
Clarification ---
1) a single God may be asked more than one question,
2) questions are permitted to depend on the answers to earlier questions,
3) The nature of Random's response should be thought of as depending on the flip of a coin hidden in his brain: if the coin comes down heads, he speaks truly; if tails, falsely.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
I guessed it asking to the three gods the same question: are you the god True? The answers will be a yes from the god True(because he always say the true), another yes from the god False(because he always answer falsely) and a yes or no from the god Random. That mean that if you her at least two 'da' you'll know it means yes. However if you hear at least two 'ja' it means no. Overall you just need thre questions one to each god