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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4
votes
2answers
318 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
votes
1answer
222 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 ...
21
votes
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
417 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
votes
3answers
629 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
votes
3answers
345 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 ...
1
vote
1answer
144 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
votes
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
169 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
202 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
votes
2answers
404 views

Smullyan Logic Puzzle about Nelson Goodman Principle - Knights and Knaves

In Smullyan's "Logical Labyrinths" there is the following problem 1.11: ...
8
votes
1answer
271 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
votes
1answer
375 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
votes
8answers
575 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 (...
7
votes
1answer
265 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
votes
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
votes
2answers
258 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
votes
2answers
182 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
votes
4answers
452 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 ...
1
vote
0answers
67 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. ...
36
votes
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
votes
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,...
6
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
votes
2answers
278 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
votes
1answer
244 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
votes
2answers
758 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
votes
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
votes
4answers
585 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
680 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
332 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
636 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
275 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
votes
1answer
387 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
votes
2answers
155 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
votes
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 ...
3
votes
5answers
410 views

A story about liars

Evelyn, Skylar, Alayna, Madelyn, Jonathon, Lara, Alyin, Felix, Iris, Bob and Roslina live on an island where some people always tell the truth, and the rest always lie. Roslina says "Alyin and Evelyn ...
43
votes
11answers
9k views

3 doors, three guards, one stone

You are in a room with three doors. Behind two of them, the darkest pit of hell waits for you to make a mistake. The other door leads to heaven and freedom. Each door is guarded by a guard: Michael, ...
10
votes
1answer
1k 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 ...
3
votes
1answer
4k views

Possible answer to the Heaven Hell Door riddle

There is a fairly common riddle You're standing between the door to heaven and the door to hell. A guard stands by each door. One guard always tells the truth, and the other always lies. You don't ...
1
vote
2answers
376 views

Brain twister. A simple riddle to play [duplicate]

You are lost big crowded (monster). There are only two human living Jacobe and Recode . Your task is to reach your home, there are two routes and you are confused. Conditions: Jacobe always tell the ...
2
votes
2answers
84 views

Does it exist a way to solve visually by using a grid or to find the truth among a set of five people telling different statements?

I am having problems with trying to solve this riddle therefore I am looking for help. The situation is as follows: At a semiconductor laboratory in Hsinchu a security guard caught five ...
-1
votes
2answers
116 views

who eats more fruits? [closed]

in a party 3 brothers discussing: first brother says " I ate more fruit than 2nd brother and 2nd brother ate more fruit than 3rd brother" 2nd brother says " 3nd brother ate more than me also 3rd ...
6
votes
3answers
602 views

Monty's Labyrinth

(A fun combination of two classic puzzles, hope seasoned puzzlers enjoy.) Having escaped through almost all of a labyrinth, you are met by three magical doors. Two of them lead to certain and ...
6
votes
1answer
2k views

Classic two guards and two doors

I recently heard a version of the classic two guards (one is a knight who always tells the truth and the other is a knave who always lies) standing by two doors (one leads to certain death and the ...
3
votes
4answers
683 views

The Three Mystery People- An Actual Mystery

I believe almost everyone has heard this riddle before. There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. You ...
4
votes
2answers
823 views

yes/no logic problem

There is a truth teller (always tells the truth), a liar (always lies), and one that sometimes answers truthfully and sometimes lies. Each person knows who is who. You may ask three yes or no ...
11
votes
1answer
765 views

Murder in the Royal Court

An entry in Fortnightly Topic Challenge #40: Retrograde Analysis! I can't believe it! Last night we heard a bit of fighting... but we had no idea that... our King was in check, and my fellow Rook and ...
6
votes
1answer
251 views

Truth tellers or liars among two people

Two guys, number One and number Two. You ask number One "Is there a truth-teller among you?". He replies and you have the answer to your question. What is number One and what is number Two?

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