Questions tagged [liars]

Puzzles that focus on getting information from truth-tellers (who never lie), liars (who always lie), and Jokers (who answer at random).

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167 views

Propositional Logic Puzzle [closed]

There is an island with two mythical creatures, the Komos and the Dragos. Komos loves eating visitors to the island while Dragos hates to eat visitors. One fine day, you mysteriously end up on the ...
1
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1answer
104 views

Knight can't answer about joker

If you ask a knight (True) about a Joker's answer (random), then she can't answer because she doesn't know? Does this give a NaN response or is it not allowed? I looked at similar questions and couldn'...
4
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2answers
483 views

The wrapping machines of Santa

Christmas is coming and Santa is working hard to wrap all the presents until the 24th of December. He has six wrapping machines: A, B, C, D, E and F, that work $24/7$ all at the same time. But the ...
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2answers
106 views

Guess the hat colors - Riddle 6

And for today, a new original hat guessing puzzle! CHALLENGE: Guess the hats of the 4 prisoners. SPECIAL RULE: One of the prisoners is lying DESCRIPTION: Each one can see the hats that are in front ...
8
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2answers
165 views

Great puzzle makers of yore: #1, Martin Hollis: “The Poacher's Funeral”

When Peter the Poacher died, his six direct descendants all came to the funeral, each being a son, grandson or great-grandson of the old reprobate. The "Chippings Post" sent a man to compile ...
5
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2answers
392 views

2 weird problems I came across

A man accused of murder hires a lawyer who is always believed by the court to be telling the truth. The prosecution's attorney says that if the accused man committed the murder, he had an accomplice. ...
3
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2answers
220 views

The ice cream puzzle

I am a new user, and I made this puzzle myself, but I lost the answer key, can anyone solve it so I can make a new one? The owner of the ' Super Ice Cream' shop was terrified. One of his workers was ...
8
votes
1answer
197 views

Mirror, mirror on the wall, who's the fairest of us all?

Three evil queens, accompanied by their magic mirrors, go for a girls' night out. At some point of the night they decide to finally settle the eternal question: who's the fairest of them all? Of ...
5
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4answers
1k views

One truthteller/liar and one random person

You come across two peculiar aliens: Alice and Bob. You know the following about them: -Alice is either a "truthteller" (she always tells the truth) or a "liar" (she always lies). -...
3
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3answers
300 views

Vampires, Insanity and Transylvanian Sisters

This is a puzzle from this site: https://medium.com/i-math/vampires-insanity-transylvanian-sisters-88ce3516fd I thought it was very nice, so I wanted to share it with you. WARNING: the above link ...
10
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3answers
634 views

Eight campers and the right path

In the spirit of some of my Raymond Smullyan favorites, here's a relatively hard puzzle from a Dennis Shasha collection of $1988$: Eight kids and their guide are lost on a forest exactly one hour ...
4
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6answers
950 views

Who broke the window? [closed]

There is a broken window in the house. I asked who broke the window: Gregory: I was not! April : I didn’t do it. August: April was. June : August says the truth Two of them said the truth, and two ...
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3answers
108 views

City of Lies or Truth [duplicate]

Try to solve this one: You are at an unmarked intersection ... one way is the City of Lies and another way is the City of Truth. Citizens of the City of Lies always lie. Citizens of the City of ...
4
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2answers
747 views

Two Truths and a Lie: a logic puzzle

I'm crafting an answer to the game Two Truths and a Lie: each person playing the game says three statements (usually about themselves, though I'm ignoring that requirement for this), two of which are ...
6
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1answer
240 views

Question which is sort of puzzle from mathematics Exam

I am self studying and trying questions of quantitative aptitude in my mathematics exam and I am unable to solve this problem. Of three persons $A$, $B$ and $C$, one always lies while the others ...
20
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4answers
2k views

Boys and girls in a circle

There are $28$ students in a class, and each of them are either boy or girl. They sit in a circle, and claim that “The two people next to me are of different gender than each other.” It's known that ...
7
votes
1answer
440 views

Sane and crazy persons

I have found this puzzle on internet. 40 persons sit in a round table . All of them are either sane or crazy. When you ask a person "is the person sitting to your right sane or crazy?" a sane person ...
9
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3answers
652 views

Knight and Knaves Castle

I was pretty bored in the lockdown so I thought up a mathematics puzzle, which I haven's solved yet, so the community can solve together. Let $n>1$ be a positive integer. There is a square castle ...
5
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3answers
368 views

Shocks and guesses

The Liar, the Random and Truth teller were captured and brainwashed to forget whether they always lie or tell truth or randomly answer.Everyone is handcuffed to a chair and gagged with gray, white and ...
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1answer
168 views

The Lying Brothers

The little town of Stackville is exactly like hundreds of other little communities in every respect but one. Its scenery, its stores, its churches all have their counterparts at every crossroads in ...
30
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5answers
2k views

How many spots do these frogs have?

You are approached by 5 spotted frogs who appear to be venomous, to avoid getting bitten by them, you must find out how many spots they have. The frogs with an even number of spots always tell the ...
3
votes
1answer
178 views

Fork in the road problem - with a single person

You walk to a fork from where two roads come out - one leading to a post office and the other to a university. You want to go to the university, but do not know which road would lead you to it. A ...
7
votes
1answer
215 views

Two persons and one question “Is the shaman honest”. Which one of them is the shaman?

An anthropologist arrived to the shaman's den where there were two persons, one with a green hat and one with a blue hat. One of the shaman's students had said that there was a Star Predictor with the ...
6
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2answers
443 views

Smullyan Logic Puzzle about Nelson Goodman Principle - Knights and Knaves

In Smullyan's "Logical Labyrinths" there is the following problem 1.11: ...
8
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1answer
282 views

Constructing an island according to rules in Smullyan's “What is the Name of this Book”

I've recently finished dropping my jaw at Raymond Smullyan's "What is the Name of this Book," and the section on Gödel's incompleteness theorem, involving islands of knights (truthers) and knaves (...
2
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1answer
414 views

What is the smallest number of lies needed to solve a Dragon Joust puzzle?

I recently watched this video which presents a deduction "riddle" about dragon jousting. The rules for the puzzle (from the video) are as follows: After centuries of war, the world’s ...
3
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8answers
608 views

Two doors, two guards, and two keys

Table of contents Introduction - read about where the puzzle comes from. The puzzle - read the puzzle itself. Warming up - read about solutions to a simpler variation of the puzzle. Introduction (...
6
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1answer
270 views

The scales never lie (oh yes they do!)

There are $10$ coins, one of which is a fake, and weighs either more or less than the others - you don't know which. There are two sets of scales - one tells the truth, the other lies (always says ...
13
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8answers
4k views

2 Guards, 3 Keys, 2 Locks

There are 2 guards: one only tells the truth, the other only lies. There are 2 locks and 3 keys: each lock can only have 1 key matched - the 3rd key doesn't do anything. You can only ask one ...
4
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2answers
295 views

Knights and knaves puzzler

A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet three inhabitants: Peggy, Joe and Zippy. Peggy claims, "I am a knight or ...
3
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2answers
229 views

Knight and knaves

A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet three inhabitants: Alice, Rex and Bob, where Alice tells you that "Rex is ...
7
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4answers
472 views

Island of Knights, Knaves, Spies

There are 3 types of inhabitants of a village: knight, knaves, normal. You should map each inhabitant with its type, by asking only this type of question to a person: "Hey X, what is the type of ...
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0answers
70 views

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

You are at a path and there is two roads splitting from it. The first one is certain death and the other is the way home. You do not know which way is the right way home, but there are two people. ...
35
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10answers
5k views

Knights and Knaves: What does C say?

You are on a fictional island with two types of people: knights who always tell the truth, and knaves, who always lie. Three of the inhabitants - A, B, and C are standing in the garden. A says, "B and ...
8
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12answers
3k views

Time to call the bluff [closed]

You are located outside of two rooms which have a door between them. Each room has one or more computers whose total power is unknown, so they cannot be reliably used as proof-of-work to compare times,...
5
votes
18answers
4k views

Ask one verbal question to figure out who is blind and who is mute among three persons

This is another "You can ask only one question" puzzle. This is an edited very restricted version There may be multiple answers but I could come up with only one. There are three persons in three ...
9
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2answers
287 views

Knights and Knaves on a (Not So) Deserted Island

One day, while flying your single-engine seaplane out over the Pacific, the electrical system shorts out, all of your electrical systems (including the radio) fail, and the engine dies. You are in a ...
2
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1answer
251 views

The chariot race

In a chariot race only 4 cars came to the finish: the blue, the green, the red and the white one. Titus, who is in bed with a cold, inquires to Quintus about the outcome of the race, because he ...
12
votes
4answers
4k views

The joke office

Alice and Bob are supposed to get form A at the joke office. Forms A, B, C, D and E are each at exactly one of the following five terminals. At one Terminal is only one form. Terminal 1: Here ...
14
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2answers
769 views

The alcoholic village festival

The villages Arriba and Abajo together have 2019 inhabitants. At the annual festival are more than 2000 villagers this year. When they form a huge circle for dancing, everyone calls happy: ...
21
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8answers
3k views

Robots in a spaceship

Xerxes has 6, 7 and 8-arm robots in his spaceship. Unfortunately, the 7-arm robots are misprogrammed and everything they say is a lie. The other robots are fine, they always speak the truth. Once ...
6
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4answers
589 views

Simple logic puzzle

We think of an island inhabited by rogues and knights. Rogues are always lying, knights always speak the truth. One day 12 islanders come together among which is at least one knight and at ...
15
votes
3answers
2k views

The warming up game

The theater group began today with a warming up game. Everyone has been assigned a role and is now either a bad guy who always lies, or a good guy who always tells the truth. Max, who comes late, ...
10
votes
2answers
698 views

Six liars, truth-tellers and jokers

As in this puzzle, there are three different kinds of people: truth-tellers (always telling the truth), liars (always lying) and jokers (who may either tell the truth or lie). Based on these aspects ...
6
votes
2answers
361 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, ...
7
votes
3answers
643 views

Three knights or knaves, three different hair colors

In a group of three people (A, B and C), everyone has a different hair color (blond, black or brown, not necessarily in this order) and everyone may be either a knight (always telling the truth) or a ...
4
votes
1answer
287 views

Four Doors, One Escape

You are trapped in a room with four adjacent doors upon a wall. On each door is one of the first letters of the alphabet, in order, from left to right. You know that one of the doors leads to freedom, ...
4
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1answer
389 views

Lying under arrest

I'm in a custody, under arrest, no contact with the outside world. I do not know if in that jurisdiction authorities are allowed to lie. Some real-world knowledge suggest lying by authorities is ...
3
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2answers
159 views

The truth within

Someone living in the remote cabin that you do put a virus onto your PC. Here are your suspects: Your brother, Liam, who only tells the truth about his opinions. Your sister, Irene, who tells the ...
19
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5answers
1k views

Island of Knights, Knaves and Spies

There is an island with $N$ inhabitants (for example $A_1, A_2, \dots, A_N$), each of them is either a knight, a knave, or a spy. As usual: knights will always tell the truth upon answering a ...

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