Questions tagged [liars]

Puzzles that focus on getting information from truth-tellers (who never lie), liars (who always lie), and/or Jokers (who answer at random), or which use such characters as an integral part of the puzzle.

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118 votes
16 answers
1.4m views

Two doors with two guards - one lies, one tells the truth

You are a prisoner in a room with 2 doors and 2 guards. One of the doors will guide you to freedom and behind the other is a hangman–you don't know which is which. One of the guards always tells the ...
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  • 5,400
18 votes
3 answers
3k views

Knights and jokers

There are $N$ men. $K$ of them are knights, $M$ of them are jokers. $N$ is known, $K$ and $M$ are unknown. You know that: $K + M = N$, $K \gt M$, $M \ge 1$, $N$ is odd. Knights always tell the truth, ...
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  • 15.8k
17 votes
11 answers
13k views

Knight, Knave and Joker puzzle

Here is an excellent puzzle with 3 types of characters: You are lost in a town and meet 3 men. You somehow (God told you) know that they are Knight, Knave and Joker. Knight always tells truth, ...
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  • 15.8k
15 votes
2 answers
2k views

Knights and knaves in a foreign language

You die and ascend to heaven, there is a knight (truth-teller), a knave (pure liar) and a joker (random) sitting on a cloud - they all look the same. In order to gain entry you must determine their ...
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  • 12.7k
10 votes
3 answers
2k views

The Expedition Into The Ancient Cave

You are a archeologist and have taken 8 of your students on a expedition trip to a ancient cave to try and find ancient treasure. After you and your team entered the cave, you travel as a group ...
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22 votes
6 answers
11k views

Which teacher is the murderer?

In the first day of a new class semester, a student was murdered inside the classroom. No witnesses, no murder weapon, and no evidence. The police got four teachers as possible suspects, but they all ...
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  • 383
13 votes
7 answers
2k views

Faulty computers

You have $99$ computers in a LAN room, and you know that at least $50$ are working. The others can be faulty. The only thing you are allowed to do is to ask computer $i$ the question "Is computer $j$ ...
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  • 749
13 votes
4 answers
7k views

Who is the thief? An elementary school teacher had her purse stolen

This puzzle is not mine, but I couldn't find an original source. I edited it somewhat. An elementary school teacher had her purse stolen. The thief had to be Sammy, Karin, Arnold, Harry, or Liza. ...
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  • 457
31 votes
1 answer
4k views

Murdered down the Rabbit Hole (a long logic puzzle)

Backstory Disaster has struck for Leporidae throughout the fantasy realm -- a mass carrot famine has wreaked havoc upon all existences but our own. Because of this, 25 of the leading fantasy bunnies, ...
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  • 16.9k
25 votes
12 answers
6k views

Kill the jokers! - Part 1

The famous and ruthless explorer Wyoming Wilbert reports in one of his books that he once visited an island inhabited by jokers and truth tellers. Truth tellers always tell the truth, whereas jokers ...
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  • 11.5k
25 votes
4 answers
9k views

King Octopus and Servants Puzzle

Puzzle: King Octopus has servants with six, seven, or eight legs. The servants with seven legs always lie, but the servants with either six or eight legs always say the truth. One day, 4 servants ...
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32 votes
2 answers
3k views

The Second Hardest Logic Puzzle in the World

This puzzle is an original creation of mine (as far as I know), although other people have solved it before me. You meet five people: Alice, Bob, Carol, Daniel and Evie. Your aim is to ask yes/no ...
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  • 807
20 votes
8 answers
12k views

Logic puzzle - 3 suspects

An inspector knows that exactly one of 3 suspects committed a crime, and interviews them to find out which. Each person lies one time, and tells the truth the other time. A says: I did not do it. B ...
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  • 209
26 votes
3 answers
2k views

A Space Station 13 tricky situation

You are the Captain of the Space Station 13, and everything went bad very quickly. Most of the crew died, and it took you not so long to figure out that some people are not who they're supposed to be (...
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  • 12.6k
18 votes
3 answers
2k views

Lies, damned lies, and statistics

A (hopefully) new variant on the Knights & Knaves problem. On the island of D'Israel, the inhabitants fall into three types: Liars, Damned Liars, and Statisticians. They are visually ...
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10 votes
3 answers
22k views

Knights , Knaves and Spies - Part 1

I was working my way through some Knight and Knave Puzzles in Discrete Maths by Rosen, when I came across the following question: There are inhabitants of an island on which there are three kinds of ...
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  • 995
28 votes
5 answers
1k views

Council of Magic - a palace of deceptive spellcasters

Council of Magic: The King of Puzzlington has sent you to a distant palace to gain the aid of the Council of Magic. As your luck would have it though, spellcasters are a tricky sort. There are 4 ...
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  • 3,909
12 votes
3 answers
940 views

A Space Station 13 complicated escape

After successfully resolving this tricky situation, you, the Captain of the Space Station 13, have ordered what remains of your crew to gather in the escape shuttle. Accompanied by the Security ...
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  • 12.6k
11 votes
9 answers
16k views

Survive from death by asking the right question from trolls [duplicate]

You are in the intersection of two roads, there is a troll in the beginning of each road. One of them is liar (always lies), and one of them always tells the truth. One of the roads, ends to your ...
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10 votes
1 answer
2k views

Island of Liars

A king goes to an island, where there are 5823 people who always tell the truth and 8723 who always lie. The king is special guest for the party celebrating 2053 year. On the party, liars and ...
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10 votes
3 answers
2k views

Knights and liars

An island is inhabited by both Liars and Knights. Knight always tells the truth and Liar always lies. One day 12 islanders gathered together and issued a few statements. 2 of the islanders said "...
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6 votes
4 answers
1k views

5x5 statement table

Statement table. 3 2 1 4 1 2 3 3 3 3 3 4 6 4 4 2 3 4 4 3 1 1 2 4 3 Above 5x5 table contains numbers. A number at each cell represent a statement. x : This ...
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2 votes
2 answers
499 views

T Knights, L Knaves and R Jokers

Following these questions: Faulty computers, Knights and jokers I wonder, what if the conditions are the following: We have T Knights (truth-tellers), L Knaves (liars) and R Jokers (random-...
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  • 15.8k
1 vote
3 answers
4k views

Puzzle : Who is Corrupt in the Senate?

I was working my way through some puzzles in Discrete Maths by Rosen, when I came across the following question: Freedonia has fifty senators. Each senator is either honest or corrupt. Suppose you ...
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  • 995
6 votes
5 answers
625 views

Identify who is who between 3 persons who tell the truth and lie alternately

Dipsy tells the truth in 1 day and lies in the next day alternately. If today he tell the truth, tomorrow he will lying, 2 days later he will tell the truth, and so on. Lala tells the truth in 2 ...
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2 votes
4 answers
1k views

The way to Acarien, with Knights and Knaves

Once again, you're on your way to Acarien. You find yourself in a land of Knights and Knaves, who understand your language but don't speak it. You understand nor speak their language, but you do know ...
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  • 4,956
36 votes
8 answers
7k views

Who committed the crime?

A crime has been carried out by one person, there are 5 suspects. Each suspect is asked under polygraph who they think committed the crime. Their answers are as follows: Terry : It wasn't Carl, It ...
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33 votes
23 answers
5k views

Unfortunately, you died [closed]

Your soul is on its way to the afterlife when suddenly you arrive in a room. You look around and notice six humanoids staring at you. You walk toward them and you can suddenly hear them talk between ...
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  • 9,786
13 votes
2 answers
1k views

Name the trolls

TL;DR There are 11 trolls named and you should discover their names by asking yes-or-no questions to them, directing each question to one troll. You must use the minimum possible number of questions. ...
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33 votes
10 answers
6k views

Liar liar pants on fire

Here is an easy and straightforward liar puzzle. Four people are in a room, stack reader, boboquack, Rand al'Thor and Brent Hackers. stack reader states that at least 2 of the other 3 are liars. ...
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  • 9,786
17 votes
2 answers
2k views

Automatically a Knight, Knave, and Joker

Let M be a finite positive integer. It's exact value is not known. Suppose we have three classes of automaton, all of which accept a bit stream as input, produce a bit stream as output (one bit per ...
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  • 9,973
13 votes
4 answers
43k views

Two doors with three guards - one lies, one tells the truth, and one is unreliable

This is an extension of Two doors with two guards - one lies, one tells the truth, but in this situation you are a prisoner in a room with 2 doors and 3 guards. One of the doors will guide you to ...
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  • 544
24 votes
4 answers
2k views

Art Accident at Airport!

There was an accident at the airport! A hanging art installation fell and landed on some passengers. In addition to tearing up all their tickets and mixing up their luggage, six people sustained ...
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  • 4,559
18 votes
4 answers
3k views

Past, Present and Future

There are 3 gods, named Past, Present and Future, who all look identical. They sit in a throne room, with one in the middle, the others on the right and left. You are allowed to ask them a series of ...
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  • 31.4k
17 votes
9 answers
4k views

Three boxes, Four questions, Three times not true, Once the truth

There are 3 boxes, only one of which contains a treasure. The guardian will only answer you truthfully once, the other three times he will lie. You may ask 4 YES or NO questions. Which questions ...
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  • 281
14 votes
9 answers
3k views

Find the correct door!

This is my first puzzle but I hope it will work out well and that everyone can enjoy it. While trying to get out of a dungeon, you arrive in a circular room with 5 doors at equal distances from each ...
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  • 9,786
13 votes
3 answers
1k views

Truths, Lies, and Xors

Rusty is a member of the highly secretive Logician's guild. After years of grueling trials, he is now finally allowed to meet the three leaders of the guild. Their names are Truman, Lyle and Xavier, ...
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  • 31.4k
6 votes
3 answers
951 views

How would one make a good liars puzzle?

I’ve seen and made a few liars puzzles, and a recurring theme with liars puzzles is that they can be too easy, and can be dull, perhaps a bit repetitive. How can you come up with a Liars puzzle that ...
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  • 3,674
6 votes
3 answers
617 views

Which of my friends has a birthday today?

I have five close friends, Andrew, Benjamin, Cassie, Danielle and Eric. I know that one of them has a birthday today but I can't remember which. I asked Andrew who had a birthday today, and he ...
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  • 3,674
21 votes
4 answers
7k views

Who stole the flying car in Hogwarts?

During a trial in a Hogwarts court, Ron claimed that the Flying Ford Anglia car was stolen by Hermione. Then Hermione and Harry gave testimonies which, for some reason, were not recorded. Later on ...
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  • 660
7 votes
3 answers
688 views

One truthteller, one liar, and two randoms - least questions to identify?

I have landed on a new planet and there are 4 people there. One of them is a truth teller and they always speak the truth. The other is a liar and they always lie. The other 2 are random and they ...
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-3 votes
2 answers
679 views

3 guards, 3 objects, 3 monsters and 3 questions

You are standing before 3 objects. You need to give the right one to the right monster or else you'll die. There are 3 people in front of you for you to question. One always lies, one always tells ...
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28 votes
5 answers
6k views

You trolls, get out of my party! [duplicate]

You have invited $2017$ of your acquaintances to a party. But after they all arrive, you come to know from a reliable source that each of your guests is either a troll or a true friend. You don't know ...
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  • 17.7k
9 votes
3 answers
657 views

Council of Magic, 5 years later - more spellcasters, more deception

Council of Magic - 5 Years Later: Five years ago, you managed to gain the support of the Council of Magic. However, now the King of Puzzlington needs their aid once again. As it worked last time, he ...
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  • 3,909
8 votes
1 answer
937 views

Kill the jokers! - Part 2

The famous and ruthless explorer Wyoming Wilbert reports in the third part of his memoires that he once visited an island inhabited by jokers and truth tellers. Truth tellers always tell the truth, ...
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  • 11.5k
7 votes
2 answers
560 views

How many knights

In a room are 13 men, who are either Knights (truth tellers) or Knaves (lie tellers). the first man looks around and says "The number of knights in this room is no greater than one" the second man ...
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  • 1,302
1 vote
2 answers
6k views

Nine togglers, one truth teller, and only a single question

You are standing in front of ten people, one of which is a truth-teller while the other nine are togglers . (A toggler is a person who toggles between the-truth and the-lie for every question asked.) ...
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10 votes
1 answer
989 views

Who stole my laptop?

It’s obvious that one of my “friends” was lying to me back in March this year. Someone who knew I’d be gone stole my $1,500 laptop and my crappy old broken microwave (I probably won’t ask for that one ...
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9 votes
1 answer
1k views

The Old Millionaire

A very old man has a million dollars, which he's going to pass down to you! He has 3 associates who have been ordered to help you. The 3 associates know the location where it is, and they tell you it ...
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  • 14.2k
7 votes
2 answers
514 views

Liars, truth-tellers and jokers

In a strange village there are three kinds of persons: knights (always telling the truth), knaves (always lying) and jokers (who may either tell the truth or lie). A, B, C and D live in this village, ...
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  • 426