# 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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### Solving truth liar random puzzles without self refernce questions

You’re a logician who wants to know which of two roads leads to a village. Standing nearby, inevitably, are three natives: one always lies, one always tells the truth, and one answers randomly. You ...
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### Is Heaven real?

You stand before an omniscient being. It is either God, who always tells the truth, or the Devil, who always lies. You don't know which. Your task is to figure out whether Heaven is real. You may ask ...
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### Twins, identify the liar, find out their identity

Arthur and Robert are identical twins. One is a knave and he always lies. The other is a knight and always tells the truth, but you don’t know which one is which. One day you meet one of them and want ...
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### How many of the four Knaves were telling the truth?

Beginner puzzle This puzzle is intended to be suitable for people who are new to puzzle solving. Clarification: Both experienced solvers and new solvers are welcome to post solutions to this puzzle. ...
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### Identify the truth teller, the liar and the spy

Beginner puzzle This puzzle is intended to be suitable for people who are new to puzzle solving. Clarification: Both experienced solvers and new solvers are welcome to post solutions to this puzzle. ...
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### Knights, Knaves, and Spies [closed]

I need help understanding this problem. An island has three kinds of inhabitants: knights, who always tell the truth, knaves, who always lie, and spies, who can either tell the truth or lie. You ...
178 views

### Generalized knights and knaves puzzle

A basic knight-knave puzzle (for the purposes of this question) takes the form $Q(n, s, k, x)$, where: $n$ men are guarding $n$ doors. The guards and doors are numbered for easy reference: Guard #1 ...
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### 3 doors guarded by 1 knight and 2 knaves

3 men are guarding 3 doors. 1 door leads to a pot of gold, while the other 2 lead to hungry lions. 1 guard always tells the truth, and the other 2 always lie. You are allowed to ask 2 questions in ...
• 173
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### The Room Of Tiles

You are stuck in a room with 100 floor tiles, and a magic button which you can carry with you. There are three types of tiles: real, fake and nopey. There are at most 49 fake tiles, and there is at ...
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### How many Friends are there in the circle?

On the island of Friends and Foes, every citizen is either a Friend (who always tells the truth) or a Foe (who always lies). Seven citizens are sitting in a circle. Each declares “I am sitting between ...
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### Off-duty guards on liar island

It's a little-known fact that the guards on Liar Island have to continue their slavish devotion to the individual rules dictating the veracity of their statements. Of course, some always lie, and some ...
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### The Enigmatic Orbs

You find yourself in a peculiar room with three orbs placed on pedestals. Each orb has a unique color: red, blue, and green. A mysterious inscription on the wall reads: "Arrange the orbs in the ...
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### The Omniscient Vegetable

You've just broken into your half-sister's boyfriend's mother's secret stash. It is full of all sorts of magical devices, including a strange vegetative organism. According to some notes your friend ...
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### Minimum number of questions for real treasure

There are 2000 treasures, among which only one is real and the others are fake. There are also 2000 knights, among whom one always tells the truth while the others always lie. You can ask the knights ...
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### Lions vs. Pokémon

It is the year 10,000,000,000, and materalisation has been invented. At the same time, Nintendo has materialised every single Pokémon (countably infinitely many now!) to fight against finitely many ...
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339 views

### 5 guards, and get rid of the timer!

I like the lies and statistics question, but it is a bit too violent, so I suggest a (slightly harder) and way less violent version. You are looking at the basement of your house, and you see three ...
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### Murder Mystery. Who is the killer?

There is a riddle about a Murder Mystery. My friend, who is studying law, gave me this puzzle. It was originally given to him by his professor, who often gives puzzles to his students. There are 7 ...
• 161
284 views

### Benny, Denny, Kenny and Lenny: Who lies and who tells the truth?

To allow new users to solve this puzzle and earn reputation points, I encourage all users whose reputation is 200 or more to not post an answer until 48 hours after this question is posted. Thank you! ...
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399 views

### The Island of Careful Thought

Everyone who lives on the Island of Careful Thought is either sane (believing all true statements, and no false statements) or insane (believing all false statements, and no true statements). The ...
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906 views

### Who are the space adventurers?

I got this puzzle from a friend and thought it was a good one for this community: In this space adventure, women from Neptune and Men from Jupiter always speak the truth, while men from Neptune and ...
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### Knights and knaves variations

The knights and knaves puzzle is old, well known and thoroughly solved. https://en.m.wikipedia.org/wiki/Knights_and_Knaves In Labyrinth there's a variation, where one of the participants tell us the ...
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### The thief, liars, and the honest

There are four people: A, B, C, D. One person is a thief, the thief and two other people are lying. The other person is telling the truth. Who is telling the truth? A: I am not the thief. B: D is ...
498 views

### One always tells truth and the other lies, figure which is which in only n tries

Here's a simpler and finalized version of the puzzle, the previous got messy due to its WIP status. Enter the hall of the twin oracles. One of the oracles is true, and its purpose is to always tell ...
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956 views

### Was Humpty Dumpty right?

Raymond Smullyan's What is the Name of This Book? contains a puzzle which I'll paraphrase here: Of the identical twins Tweedledum and Tweedledee, one of them lies on Mondays, Tuesdays and Wednesdays ...
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203 views

### Beauty, chef and boxer

Sarah, Megan, and Mike all attended a party last night. Sarah is a beauty pageant winner, Megan is a chef, and Mike is a boxer. The host of the party said that one person told a lie during the evening,...
376 views

### An Infinitude of Perfidious Pupils

Here's an original puzzle I created. Enjoy! A teacher had infinitely many students, and he referred to them by the designations $\text{Student } 0$, $\text{Student } 1$, $\text{Student } 2$, and so on....
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### An Infinitude of Deceptive Devourers

Here's an original puzzle by me. I hope you enjoy! A mother had infinitely many children, with the following names: $\text{Albert}_1$, $\text{Albert}_2$, $\text{Albert}_3$, … , $\text{Beth}_1$, \$\text{...
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### Knights and knaves not on an island

On a fictional island there were two types of people: knights who always told the truth, and knaves, who always lied. They got irritated by people asking them so many questions so they all moved to ...
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### Two doors and two guards (variant) [duplicate]

So, I've finished building my "Island of Logic!", where there are a number of puzzles for travellers. So far, I have a bunch of rivers with river craft, wolves, goats, and cabbages; and a ...
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### In relation to "the two door riddle," what is which door either guard is guarding logically dependent upon?

Link to the two door riddle: https://nerdist.com/article/how-to-beat-the-labyrinth-two-door-riddle/ Question: In relation to "the two door riddle," what is which door either guard is ...
500 views

### Solving this "Who committed the murder" puzzle using truth tables or propositional logic

I'm trying to solve a logic problem, and I'm wondering if it can be done using truth tables or propositional logic. The problem goes like this: Who killed the mouse? The owl said the hawk did it. ...
1 vote
501 views

### Understanding solution for this puzzle where truth-tellers and liars describe game scores

Source (Page 26-28) Frieda was fond of visiting exotic locations. On her visit to the island of Yippiekaiyay, she was surprised that the natives of the island could be classified into one of two ...
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1 vote
241 views

### Need help solving the 'Who killed the vole' puzzle - Can you crack the code? [duplicate]

I am hoping to get some help with a puzzle that I've been struggling with. The puzzle is called "Who killed the vole" and it goes like this: There are four birds - hawk, owl, sparrow, and ...
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### Two Doors and a Guard

While trekking through the swamp of Knights and Knaves, you come upon a pair of doorways: One leading out of the swamp, the other leading to your doom. The swamp of Knights and Knaves is a strange ...
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1 vote
376 views

### A Possible Solution to George Boolos' "The Hardest Logic Puzzle Ever"

The full explanation of the puzzle, by George Boolos, can be found here. Basically, it goes as follows: Three gods A, B, and C are called, in no particular order, True, False, and Random. True always ...
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### The Fourth Hardest Logic Puzzle Ever

This is a beautiful variant of "The Hardest Logic Puzzle Ever". I learned it in high school math class a while ago. (I do not know if my teacher invented this variant.) I know the solution ...
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### Which gnome is the tallest?

This is a riddle I and some friends came up with. Say I have four gnomes with different heights. They state the following: Gnome 1: I am the shortest. Gnome 2: I am neither the tallest nor the ...
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491 views

While walking through the forest, on the way to confess to your crush, you come upon an old house. Outside of this house is an old, damaged Brazen Head, with a hastily wired coin-slot appended beside ...
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### This logic puzzle is impossible!

Rocks always tell the opposite of a statement and Rolls tell the truth. If I was to tell you the following: A says C is a roll. A says there are 2 rocks. B says they are a roll. C says they are a ...
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### Truths tellers and liars. A short one

On a strange island five people are living. Of the one half we know: they only speak the truth, of the other half we know: they only speak lies. How is that possible?
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### Get the treasure from an island of knights and a joker

You've learned that there's treasure buried somewhere on a small island, but not exactly where. The island is a perfect circle with a radius of 25 meters. There are 15 islanders there, one of whom is ...
1 vote
166 views

### Knights and Knaves [closed]

You are visiting an island with two types of people: knights who always tell the truth and knaves who always lie. From among the thousands of people who live on the island, you meet six people who ...
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### A logic puzzle with some lateral thinking

Original puzzle below created by me. The writing is... to be honest, not that good, but it's a puzzle. Focus on the puzzle part. Your name is John D. Tectif, and you're looking for 4 notorious ...
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1 vote
83 views

### Truth, error, and random [duplicate]

There are three machines named "truth," "error," and "random" (but you don't know who they are). Among them, "truth" always tells the truth, "error" ...
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1 vote
281 views

### Find Out Our Numbers (liars and truth-tellers)

You are an adventurer to a distant jungle that the news told you it was full on secrets. But, you could not find anything! So you decided to head home. When you were almost there, a troll (you ca't ...
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### Police Interrogation Puzzle [closed]

I have tried so hard to solve this puzzle. But I cannot get my head around it. I have attempted to eliminate the lies and I have come up with Dave as the criminal. But I do not know if it is the ...
1 vote
193 views

### The Truth And Lies Today: Revisited

A man is only capable of telling the truth four hours a day. They are either TTFTT or TFTTT (equiprobable). For the other twenty hours, he lies. All hours between 7pm and 6am are night; 7am and 11am ...
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1 vote
206 views

### The Truth And Lies Today

Suppose a man only tells the truth three hours a day. It is the same every week and it is known that the pattern of the truth hours are TFTFT. (which means he may tell the truth at midnight and 2am ...
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### Which day of the week is today (Tuesday, Wednesday, Saturday or Sunday) if one of the statements is false?

Today is neither Sunday nor Wednesday. Tomorrow is not Sunday or Wednesday. Yesterday was not Friday. Monday was not the day before yesterday, neither was Sunday. Which day of the week is today (...
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