There are two doors. You have to pick one door. One door leads to great happiness, the other leads to great suffering. But you don't know which door is which.
However, there are two people in the room. One of them always tells the truth, but one of them always lies. But, you don't know which is which.
You can only ask one question. What question should you ask in order to determine which door leads to great happiness?
2006-10-10 16:42:49 · 18 answers · asked by PJ 3 in Entertainment & Music ➔ Jokes & Riddles
Just ask either of them which door the other person would say is the 'Happiness' door. Pick the other one and you're in good shape.
If the Happiness door is on the left, the liar will say (about the honest one) "He would choose the right door" and the honest persone would say "He would choose the right door". Get it?
2006-10-10 16:44:36 · answer #1 · answered by envision_man 2 · 3⤊ 0⤋
Two Doors One Question
2017-01-11 14:03:33 · answer #2 · answered by ? 4 · 0⤊ 0⤋
The "what would the other guard say" inquiry may be at risk of compound error depending on the nature of the liar; the question is a composition of Boolean functions with "which door leads to life" and "what is the other guard s type" as the logical parameters, such that if the liar negates each of the results of each function, one might get an answer differing from the door pointed to by the truth teller. For example, if the left door leads to life, the liar may first answer the question "which door leads to life," negating the answer to "right," and then using "right" for the parameter of the question "what is the type of the other guard," he would negate the answer to "left." This presents a problem.
Thus, we must use compounding error to our advantage. Ask each guard instead: "Presume a Boolean variable L, representing the truth value of whether or not the door on the left leads to life or death, such that L=0 if the left-hand door leads to death and L=1 if it leads to life; what is the truth value of (L⊕L)∧(L⊕1) [spoken as "(L XOR L) AND (L XOR 1)"], represented also as a Boolean variable of the same orientation." Thus, the honest guard will always say "0," as (L⊕L) returns 0 for any L, (L⊕1) returns ~L for any L, and 0∧A returns 0 for any A. Thus, the honest one will always say 0. However, the liar will begin a process of compounding error; if L=0, he will begin by negating (L⊕L) to return 1, and then will negate (L⊕1) to return 0, and then will negate (1∧0) to return 1; if, however, L=1, he will begin by negating (L⊕L) to again return 1, then negate (L⊕1) to return 1, and finally will negate (1∧1) to return 0. Hence, if L=0, our responses from our two guards will be 0,1, and if L=1, our responses will be 0,0. Therefore, if our answers from our two guards are congruent, we can deduce that L=1, and therefore the left-hand door leads to life and we should go through it; else, if our answers are conjugate, we can deduce that L=0, and the left-hand door leads to death, such that we should avoid it and go to the door on the right, which leads to life.
This is a more thorough and mathematically justified answer, but we must be careful to first determine the type of lying we should expect before asking.
2016-09-21 05:28:49 · answer #3 · answered by Shayquanne 1 · 0⤊ 0⤋
Ask one person "which door would the other person tell me to go through?" and pick the other door.
2006-10-10 16:44:44 · answer #4 · answered by bardstale 4 · 3⤊ 0⤋
DEPENDS ON MY LUCK, I'll ask one the 1 on the left "which door leads to happiness??", if he says the 1 he's in front of. It means he's lying. I'll take the other side coz liars alwayz tell good things about themselves.
2006-10-10 18:16:56 · answer #5 · answered by Anonymous · 0⤊ 1⤋
ask either person which door the other one would tell you to take, and then take the other door.
2006-10-10 16:45:06 · answer #6 · answered by jperk1941 4 · 0⤊ 0⤋
Ask them what the other one will say and choose the opposite. There sure must be a lot of variations of this out there.
2006-10-10 17:35:18 · answer #7 · answered by ♥Raven 6 · 2⤊ 0⤋
you will possibly ought to ask between the twins: If I have been to ask the different twin which door finally ends up in the heaven, what might he say". after which you %. the alternative door of what he tells you
2016-10-19 04:35:55 · answer #8 · answered by connely 4 · 0⤊ 0⤋
the question you must ask is "Who's lying?" The liar has to lie and the Truth teller has to tell the truth. Either way you win.
2006-10-10 16:48:49 · answer #9 · answered by huh? 2 · 0⤊ 1⤋
Didn't you ask this already? Deja vu. Hmm. Ask one of the doors what time it is or what color the sky is. Which ever one is lying, don't pick it!
2006-10-10 17:14:41 · answer #10 · answered by fat_bottom_girls_rock 3 · 0⤊ 1⤋