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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89
votes
15answers
895k 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 ...
18
votes
3answers
3k views

Knights and jokers

There are $N$ men. $K$ of them are knights, $M$ of them are jokers. $N$ is known, $K$ and $M$ are unknown. You know that: $K + M = N$, $K \gt M$, $M \ge 1$, $N$ is odd. Knights always tell ...
14
votes
1answer
2k 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 ...
16
votes
11answers
8k 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, ...
22
votes
6answers
10k views

Which teacher is the murderer?

In the first day of a new class semester, a student was murdered inside the classroom. No witnesses, no murder weapon, and no evidence. The police got four teachers as possible suspects, but they all ...
13
votes
7answers
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 $j$ ...
10
votes
3answers
1k views

The Expedition Into The Ancient Cave

You are a archeologist and have taken 8 of your students on a expedition trip to a ancient cave to try and find ancient treasure. After you and your team entered the cave, you travel as a group ...
29
votes
1answer
3k views

Murdered down the Rabbit Hole (a long logic puzzle)

Backstory Disaster has struck for Leporidae throughout the fantasy realm -- a mass carrot famine has wreaked havoc upon all existences but our own. Because of this, 25 of the leading fantasy bunnies, ...
20
votes
8answers
10k 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 ...
10
votes
3answers
12k 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 ...
24
votes
3answers
2k views

A Space Station 13 tricky situation

You are the Captain of the Space Station 13, and everything went bad very quickly. Most of the crew died, and it took you not so long to figure out that some people are not who they're supposed to be (...
16
votes
3answers
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
4answers
1k views

5x5 statement table

Statement table. 3 2 1 4 1 2 3 3 3 3 3 4 6 4 4 2 3 4 4 3 1 1 2 4 3 Above 5x5 table contains numbers. A number at each cell represent a statement. x : This ...
1
vote
2answers
390 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-...
0
votes
3answers
2k 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. ...
27
votes
5answers
1k views

Council of Magic - a palace of deceptive spellcasters

Council of Magic: The King of Puzzlington has sent you to a distant palace to gain the aid of the Council of Magic. As your luck would have it though, spellcasters are a tricky sort. There are 4 ...
12
votes
3answers
721 views

A Space Station 13 complicated escape

After successfully resolving this tricky situation, you, the Captain of the Space Station 13, have ordered what remains of your crew to gather in the escape shuttle. Accompanied by the Security ...
5
votes
5answers
507 views

Identify who is who between 3 persons who tell the truth and lie alternately

Dipsy tells the truth in 1 day and lies in the next day alternately. If today he tell the truth, tomorrow he will lying, 2 days later he will tell the truth, and so on. Lala tells the truth in 2 ...
4
votes
2answers
896 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 ...
2
votes
4answers
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 ...
35
votes
8answers
6k views

Who committed the crime?

A crime has been carried out by one person, there are 5 suspects. Each suspect is asked under polygraph who they think committed the crime. Their answers are as follows: Terry : It wasn't Carl, It ...
33
votes
23answers
5k views

Unfortunately, you died [closed]

Your soul is on its way to the afterlife when suddenly you arrive in a room. You look around and notice six humanoids staring at you. You walk toward them and you can suddenly hear them talk between ...
33
votes
10answers
6k views

Liar liar pants on fire

Here is an easy and straightforward liar puzzle. Four people are in a room, stack reader, boboquack, Rand al'Thor and Brent Hackers. stack reader states that at least 2 of the other 3 are liars. ...
16
votes
2answers
1k 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 ...
22
votes
4answers
2k views

Art Accident at Airport!

There was an accident at the airport! A hanging art installation fell and landed on some passengers. In addition to tearing up all their tickets and mixing up their luggage, six people sustained ...
18
votes
4answers
2k 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 ...
15
votes
9answers
3k views

Find the correct door!

This is my first puzzle but I hope it will work out well and that everyone can enjoy it. While trying to get out of a dungeon, you arrive in a circular room with 5 doors at equal distances from each ...
14
votes
3answers
1k views

Truths, Lies, and Xors

Rusty is a member of the highly secretive Logician's guild. After years of grueling trials, he is now finally allowed to meet the three leaders of the guild. Their names are Truman, Lyle and Xavier, ...
6
votes
3answers
574 views

Which of my friends has a birthday today?

I have five close friends, Andrew, Benjamin, Cassie, Danielle and Eric. I know that one of them has a birthday today but I can't remember which. I asked Andrew who had a birthday today, and he ...
6
votes
3answers
815 views

How would one make a good liars puzzle?

I’ve seen and made a few liars puzzles, and a recurring theme with liars puzzles is that they can be too easy, and can be dull, perhaps a bit repetitive. How can you come up with a Liars puzzle that ...
11
votes
8answers
10k views

Survive from death by asking the right question from trolls

You are in the intersection of two roads, there is a troll in the beginning of each road. One of them is liar (always lies), and one of them always tells the truth. One of the roads, ends to your ...
-3
votes
2answers
602 views

3 guards, 3 objects, 3 monsters and 3 questions

You are standing before 3 objects. You need to give the right one to the right monster or else you'll die. There are 3 people in front of you for you to question. One always lies, one always tells ...
19
votes
4answers
6k views

Who stole the flying car in Hogwarts?

During a trial in a Hogwarts court, Ron claimed that the Flying Ford Anglia car was stolen by Hermione. Then Hermione and Harry gave testimonies which, for some reason, were not recorded. Later on ...
13
votes
9answers
4k views

Three boxes, Four questions, Three times not true, Once the truth

There are 3 boxes, only one of which contains a treasure. The guardian will only answer you truthfully once, the other three times he will lie. You may ask 4 YES or NO questions. Which questions ...
9
votes
3answers
587 views

Council of Magic, 5 years later - more spellcasters, more deception

Council of Magic - 5 Years Later: Five years ago, you managed to gain the support of the Council of Magic. However, now the King of Puzzlington needs their aid once again. As it worked last time, he ...
2
votes
2answers
3k 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.) ...
10
votes
1answer
871 views

Who stole my laptop?

It’s obvious that one of my “friends” was lying to me back in March this year. Someone who knew I’d be gone stole my $1,500 laptop and my crappy old broken microwave (I probably won’t ask for that one ...
9
votes
1answer
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 ...
6
votes
2answers
499 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 ...
6
votes
4answers
281 views

A Space Station 13 malfunctioning A.I

Disclaimer: It is not necessary to read the previous puzzle, or the one before even if it continues on the same story. The current puzzle is a different one which can work as a pure standalone. ...
6
votes
9answers
1k views

Five beautiful ladies

So there are five beautiful ladies whose faces are veiled. You can distinguish them well as they have written their (correct) names Alice, Betty, Cindy, Diana and Emily on their T-shirts. You know ...
6
votes
2answers
229 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, ...
4
votes
3answers
743 views

Identify A B & C using the least number of directed logic statements (Knights, Knaves, Normals)

Here is a puzzle I have not yet been able to solve: There are three people A, B and C who know each others identity. You may pick A, B or C show him a logic statement (truth functional compounds ...
1
vote
1answer
257 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),...
-1
votes
5answers
484 views

The People Of Trutham-And-Ly

Here's an interesting variation on the classical liar puzzles: Trutham-and-Ly is a small town in the north of Logistan. It is divided into two districts, Trutham and Ly, separated by a small stream. ...