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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-1 votes
3 answers
211 views

Who is the liar?

Three friends are playing a game of memory, there are a total of 20 cards with 10 card pairs. They try to make the most pairs in a row, after everyone had a turn they make the following statements: ...
  • 1,378
14 votes
2 answers
638 views

Liar Puzzle with Stack Exchange Users

You are in a chatroom with three Stack Exchange users. They are a Spambot, a Trusted User, and a Moderator, but you don't know who is who; the chatroom only displays their names (user314, user2718, ...
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3 votes
2 answers
670 views

How does a common man solve impossibly hard truthteller/falsifier questions?

How does one solve the World's hardest puzzle, and other questions of the type? Is there a proper approach to such a question, or does one just have to be incredibly smart to do so? And here's an ...
1 vote
2 answers
1k views

What color is the statue? [duplicate]

This question has been tagged as duplicate of Two doors with two guards. What makes this questions different: Let me state the obvious about this question: you meet one islander. you ask one ...
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-3 votes
1 answer
587 views

3 suspects Logic Puzzle [duplicate]

The following puzzle was posted here, but providing answers to the puzzle was closed without a correct and complete answer being provided: An inspector knows that exactly one of 3 suspects committed ...
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 ...
  • 209
25 votes
4 answers
10k 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 ...
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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30 votes
13 answers
98k views

Three Doors, One Truth-Teller, One Question

You are in a prison. There are 3 doors, and a ghost standing in the middle of the prison. He says one of the doors is the way to freedom while the other two lead to death. You get to ask only one ...
  • 357
12 votes
5 answers
2k views

The 10 Logicians

There are two types of logicians: knights and knaves. Knights will always give a statement that is true whereas knaves will always give a statement that is false. After listening in on a conversation ...
  • 642
12 votes
2 answers
855 views

The Three Seers

Your kingdom has been aided, for as long as anyone remembers, by three great seers. These seers are all-knowing and will truthfully answer one question of any person that seeks them. This question ...
  • 538
8 votes
1 answer
942 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, ...
  • 11.5k
6 votes
4 answers
913 views

Knights and Knaves in the Wild West

Late at night at a bar in the Wild West only two cowboys from out of town are left, playing poker with the barkeeper. One of them cheats, so another throws over the table and they have a fistfight (...
  • 696
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 ...
  • 11.5k
19 votes
1 answer
2k views

The Pirates of Beal Isle - very long logic grid puzzle

Story Let me tell ye a tale: Somewhere northeast o' the Bahamas there be a tiny scrap o' rocks stickin' up out o' the sea known as Beal Island. It be a barren, rocky place, and no man ever called it ...
  • 610
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 ...
  • 31.5k
4 votes
1 answer
391 views

Ultimate family dart game

A family of 3 - a father, mother and son - are practising on a dart board. It has 3 shapes - a triangle, a circle and a square - on it. Scoring is as follows: Intersection of all 3 shapes - 5 points ...
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 ...
6 votes
5 answers
1k views

Over the Bridge, If You Dare [closed]

A young man walks through the forest. He comes to a bridge. In front of the bridge is a large man carrying an axe. The man says, "If you want to cross this bridge, you must tell me something. If ...
  • 1,460
5 votes
1 answer
697 views

Schizoid twin brothers

There are two identical twin brothers. The first one is honest, but he lies in his schizophrenic situations. The second one is well-known liar, but he tells the truth when he gets one of his ...
  • 974
4 votes
2 answers
1k views

Island inhabitants: Who lies and who tells the truth? [duplicate]

On some island, the population is split into native people and into outlanders. There are more natives than outlanders. Someone with extreme logical and mathematical thinking wants to know who are ...
  • 974
7 votes
2 answers
563 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 ...
  • 1,302
7 votes
6 answers
2k views

Knights and knaves at a party

On an island, all inhabitants are either knights or knaves. Knights always tell the truth and knaves always lie. No tribe is gender related and some people marry into a different tribe. When I ...
  • 3,144
13 votes
4 answers
44k 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 ...
  • 544
23 votes
5 answers
4k views

Knights and Knaves : Liar , Liar - How many are you?

There are 2014 persons in a row Each of them is either a Knave (who always lies) or a Knight (who always tells the truth). Each person says 'There are more knaves to my left than knights to my ...
  • 523
7 votes
4 answers
3k views

Lying, truthful and merciless guards (variation)

This is a variation of the riddle of 2 guards and 2 doors: You are stuck in a room with 3 doors. Each of the doors have a guard posted. One guard always tells the truth, one always lies, and the ...
  • 193
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 ...
  • 995
45 votes
10 answers
20k views

Puzzle: Who hacked the computer?

I was working my way through some Knight and Knave Puzzles in Discrete Maths by Rosen, when I came across the following question: Four friends have been identified as suspects for an unauthorized ...
  • 995
2 votes
2 answers
3k views

Knights , Knaves and Spies - Part 2

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 ...
  • 995
10 votes
3 answers
23k 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 ...
  • 995
3 votes
1 answer
5k views

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

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 ...
  • 995
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. ...
  • 457
1 vote
2 answers
544 views

If The Knights and Knaves got together [closed]

If the island of knights and knaves got together and there were n people, including a joker, how many questions would it take for all of the knights and knaves found the joker? Nobody knows who each ...
  • 14.2k
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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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 ...
  • 4,996
1 vote
1 answer
301 views

T Knights, L Knaves and R Jokers with one question type only

I would like to try more strict conditions for puzzle, which frodoskywalker solved so simply. Basically all the same, but only one type of questions is allowed. We have T Knights (truth-tellers),...
  • 15.9k
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 ...
  • 14.2k
8 votes
3 answers
1k views

Teenage Knight/Knave/Joker

You find yourself in the usual situation with three locals whose answering is highly restricted. First, they can only answer yes or no questions. Second, one will always answer truthfully, one will ...
  • 5,417
2 votes
2 answers
509 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-...
  • 15.9k
4 votes
2 answers
2k views

Knight/Knave/Joker - impasse challenge

You are at an impasse with 30 doors - 29 of them lead to endless wandering the depths of hell - and one of them leads to paradise. In front of them stand the typical trio of good friends, a Knight, a ...
  • 12.7k
0 votes
2 answers
535 views

Is there probability based Knight-Knave puzzles?

Have you seen Knight-Knave puzzles based on probability rather then facts? For example a puzzle with condition like this: Knight tells the answer, probability to which according to his knowledge is ...
  • 15.9k
4 votes
1 answer
840 views

The knaves come out at night

Standard knights and knaves problem. There are 10 people in a room, you know that each person will either always tell the truth or always lie, but you don't know who is a truth teller or liar. You ...
  • 1,451
-4 votes
3 answers
17k views

Crossroad with an Indian from one of two tribes [duplicate]

You are on a trail in a desert. You already drank all your water, and are 2 miles from the next well. There is a crossroads in the trail. One path leads directly to the fountain, and one leads out ...
  • 249
15 votes
2 answers
3k 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 ...
  • 12.7k
14 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 $j$ ...
  • 759
18 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, ...
  • 15.9k
5 votes
2 answers
2k views

The 3 Talking Hats

There are 3 talking hats on the table. Each can ask 2 questions, to either hat. 1 of them speaks only truth. 1 speaks only lies. 1 can speak only when spoken to, he will speak at random. YOU know who'...
  • 14.2k
3 votes
5 answers
1k views

About Knights and Knaves and their consistency

On an Island of Knights and Knaves (where Knights always tell the truth and Knaves always lie), a Knight will never contradict himself unless some true fact changes. I was wondering: can a Knave ...
3 votes
3 answers
2k views

About the island of Knights and Knaves

On one of the Islands of Knights and Knaves you land for the purposes of an anthropological survey. The Island has Knights who always tell the truth ( if they know enough information regarding a ...
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 ...
  • 5,400

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