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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3 votes
1 answer
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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 ...
Lise Andreasen's user avatar
14 votes
9 answers
3k views

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 ...
ChickinBorgur's user avatar
-6 votes
5 answers
454 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 ...
dtech's user avatar
  • 97
6 votes
4 answers
926 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 ...
fblundun's user avatar
  • 1,367
-6 votes
1 answer
186 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,...
Uk rain troll's user avatar
11 votes
1 answer
351 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....
Gavin Dooley's user avatar
36 votes
2 answers
1k views

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{...
Gavin Dooley's user avatar
10 votes
6 answers
3k views

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 ...
Will Octagon Gibson's user avatar
0 votes
0 answers
75 views

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 ...
enkorvaks's user avatar
  • 296
-3 votes
2 answers
212 views

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 ...
Dennis Francis Blewett's user avatar
-1 votes
2 answers
270 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. ...
cricket900's user avatar
0 votes
1 answer
413 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 ...
Fin27's user avatar
  • 111
1 vote
1 answer
225 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 ...
cricket900's user avatar
3 votes
2 answers
2k views

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 ...
Ichthys King's user avatar
  • 1,185
1 vote
1 answer
273 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 ...
ducky628's user avatar
11 votes
3 answers
681 views

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 ...
3m0o's user avatar
  • 293
37 votes
3 answers
3k views

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 ...
user1098302's user avatar
6 votes
1 answer
478 views

The Old Brazen Head

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 ...
Ichthys King's user avatar
  • 1,185
15 votes
4 answers
4k views

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 ...
Beastly Gerbil's user avatar
-4 votes
2 answers
181 views

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?
Florian F's user avatar
  • 26.8k
7 votes
4 answers
662 views

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 ...
Joseph Sible-Reinstate Monica's user avatar
1 vote
2 answers
157 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 ...
Emily's user avatar
  • 19
3 votes
2 answers
375 views

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 ...
Auride's user avatar
  • 624
1 vote
0 answers
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" ...
Mr Monkey's user avatar
  • 101
1 vote
1 answer
205 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 ...
HelloWorld's user avatar
-5 votes
1 answer
304 views

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 ...
Ogzibok's user avatar
1 vote
1 answer
189 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 ...
HelloWorld's user avatar
1 vote
1 answer
201 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 ...
HelloWorld's user avatar
-1 votes
2 answers
680 views

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 (...
Xyzq's user avatar
  • 11
4 votes
4 answers
233 views

Constraint Satisfaction Problem: who killed Warren White?

Warren White was found shot dead one morning, police have then investigated who was behind the incident. There were 3 suspects who could be suspects in the incident. That afternoon, the 3 suspects ...
Jamklok's user avatar
  • 41
3 votes
2 answers
423 views

I'm not a robot, I'm not a MONKEY

The city of Roboville has been invaded by robots, monkeys, and dancers, who will dance if the beat's funky. Some of the invaders can be two of them (e.g. both monkeys and robots) and some can be all ...
HelloWorld's user avatar
0 votes
2 answers
397 views

Is this Among Us logic puzzle possible? [closed]

In 11 Among Us players, some of them are crewmates, who always tell the truth, and imposters, who can either lie or tell the truth. Can you figure out who the imposters are? (There can be any number ...
HelloWorld's user avatar
5 votes
1 answer
225 views

Sobot or fauxbot?

Through the bustling hallway, you followed your speed-walking, speed-talking brother, who was hoping to submit an article about the upcoming demonstration to his beloved Logic and Philately Semi-...
C. P. Boyko's user avatar
4 votes
2 answers
645 views

You are left on a deserted island with 15 trolls

You are left on a deserted island with 15 trolls and you must identify who is who to leave. A tells the truth (truthful) B lies (liar) C always says yes (yes taker) D always says no (no taker) E says ...
HelloWorld's user avatar
4 votes
1 answer
263 views

Thieves for questioning

The police got three thieves when they tried to rob a bank. But the officer wants to give them a chance to get free, so he asks them who is the main brain behind the robbery. The thieves were puzzle ...
Sketch's user avatar
  • 43
6 votes
7 answers
2k views

Probability that truth is spoken on Thursdays

A man speaks the truth on only two days a week. The days are the same for each week and they are in the TFT form (TFT = True False True. This means that the days on which he speaks the truth are ...
Hemant Agarwal's user avatar
-3 votes
1 answer
172 views

2 blue eyes 99 red eyes

There are 101 normal people on an island. 2 have blue eyes and the rest have red eyes. The people with red eyes can leave the island. But the people with red eyes always tell the truth and the people ...
Varun W.'s user avatar
  • 1,313
4 votes
1 answer
973 views

Puzzle 1.3 from Montague island mysteries

I'm on puzzle 1.3 "The Missing Painting" in the book Montague island mysteries The Missing Painting An envelope that was pushed under your door during the night contains this piece of ...
Jess Thayer's user avatar
8 votes
1 answer
503 views

Identify someone as a truth-teller, liar or toggler with one yes/no question

You are visiting an island and need some information. The island has liars, truth-tellers, and togglers. Critically, togglers alternate truths and lies in their answers. When you meet someone, how can ...
Emerson's user avatar
  • 89
29 votes
2 answers
3k views

Liar Wordle - Yet Another Wordle Variant!

In Liar Wordle, standard rules apply except each row contains exactly one clue of the wrong colour. For instance if we consider only the first row the correct colours could be Y-B-B-B-Y and the ...
happystar's user avatar
  • 7,444
4 votes
1 answer
247 views

The age of three ladies

Three ladies A, B and C have a discussion, where each lady says the truth twice and lies once. A: B is two years older than me B: C is 38 years old C: A is older than me B: The age difference between ...
ThomasL's user avatar
  • 11.9k
10 votes
2 answers
446 views

How many times do the magicians' coats change color?

In a small town, there live 110 magicians, who can be identified by their magical color-changing coats. These magical coats turn green whenever the wearer tells the truth, and red whenever the wearer ...
danielmike293's user avatar
3 votes
1 answer
259 views

Choose your guardian wisely!

I must issue a word of caution dear traveler. As your journey nears its end, you have one final obstacle to overcome. Ahead lies the gate of the guardians. As you might suspect, the gate is protected ...
Hazel へいぜる's user avatar
7 votes
9 answers
748 views

The Land of Truth and Lies [closed]

You live in The Land of Truth and Lies, where any of your statements may be inverted in meaning, without prior warning. For example, if you intend to say "You're looking good today", you may ...
Avi's user avatar
  • 10.4k
24 votes
11 answers
6k views

Who robbed the store?

You are investigating a shop robbery. The CCTV footage shows that there was one criminal, but it doesn't show their face. There are 10 suspects and you know that one of them is the criminal. The ...
Dmitry Kamenetsky's user avatar
0 votes
2 answers
405 views

How many liars were there at the party? [duplicate]

Andy’s birthday party has just been moved up by a week. All the toys in Andy’s room are worried about being replaced by fancy new toys. Sheriff Woody, Andy’s favourite toy, and the others are waiting ...
Gem's user avatar
  • 101
-1 votes
1 answer
336 views

A one liner question for marriage to a beautiful girl [closed]

Question: One day I saw an extremely beautiful lady on this island which consisted of only knights (that always are truthful) and knaves (that always lie) and was immediately smitten with her. I ...
Shogo Makishima's user avatar
1 vote
1 answer
276 views

Magicians, Knights and Knaves

My solution for this puzzle did not well match with the book's solution. I thought it would be good to check my argument's reasoning, though you can also propose your own answer. There is an island ...
Shogo Makishima's user avatar
5 votes
2 answers
281 views

Knight-Knave-Normal Meta-Knowledge

A traveller visited one of the islands described by Raymond Smullyan on which all inhabitants are either knights, who always tell the truth, knaves, who always lie, or normals, who can say anything. ...
fblundun's user avatar
  • 1,367
-7 votes
1 answer
160 views

The Ultimate Liars

At the bathhouse, 27 travellers arrive. According to a book they have brought, each one follows a different one of the following rules: Traveller Yes Unknown No Sheep Y Y Y Knightly Sheep Y Y R ...
Ichthys King's user avatar
  • 1,185

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