Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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

7
votes
1answer
589 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
164 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?
2
votes
3answers
177 views

Fami-liar Situation

Exactly one of Sam or Tom has family visiting. They make these statements: Sam: "Tom has family visiting, but I don't." Tom: "Sam is lying, or I am lying, or possibly we're both lying." ...
3
votes
4answers
213 views

Classic 2 Guards But With 3 Doors Instead

So the rules are almost the same : You get to ask just one question to whichever guard you want to (just 1 guard; asking both guards is not allowed) There are 2 guards, one tells the truth and ...
4
votes
1answer
106 views

A Tournament to Remember

The King: Recently we had a big tournament, worth being immortalized in the chronicles of my kingdom. Unfortunately, the court scribe misplaced the record of the final event, and we need to restore it....
-4
votes
3answers
107 views

Riddle Again, Riddle Again, What am I? [closed]

1. If a chicken says, "All chickens are liars" is the chicken telling the truth? 2. A man is traveling to a town and comes to a fork in the road. If he goes left, he goes to the liars' village....
6
votes
4answers
172 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. ...
1
vote
1answer
229 views

Tell the truth Puzzle [duplicate]

There are three people (Ajay, Bhuvi and Chandu), one of them is a Gun, one a missile, and one a robot. The Gun always tells the truth, the missile always lies, and the robot can either lie or tell the ...
11
votes
3answers
624 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 ...
23
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 (...
4
votes
3answers
417 views

The Magical Prison Riddle

(I made up this riddle myself, hope you enjoy it) A criminal was using magic to flatten a building, while everyone, except 2 people, ran away being super scared. The police of magic came, and with ...
1
vote
1answer
376 views

7 Prisoners Say

Prisoner 3 says: "Prisoner 5, Prisoner 6 and I are truthful". Prisoner 6 says: "Prisoner 5 and Prisoner 1 are truthful". Prisoner 4 says: "Prisoner 7 lies". Prisoner 1 says: "...
8
votes
6answers
497 views

Eye exam for the truth-teller, liar and joker

A, B and C went for a eye exam together for their driver licenses. All 3 of them have bad eye sight and needed their own glasses to see clearly. However only 1 of them remembers to bring the glasses....
11
votes
3answers
2k views

Knights and liars

An island is inhabited by both Liars and Knights. Knight always tells the truth and Liar always lies. One day 12 islanders gathered together and issued a few statements. 2 of the islanders said "...
18
votes
4answers
2k views

On which day The Joker usually going on a date?

You are an investigator. You are to investigate The Joker to know on which day he usually goes on a date with Harley Quinn. The Inspector said that The Joker is lying if and only if it's Monday, ...
3
votes
3answers
303 views

Who is the Culprit

One day you were at the hospital that you work at. You have 7 people you are over for their residency, since you are the head pediatric doctor. There was Ava, Ben, Chris, Delilah, Evan, Francine, and ...
11
votes
1answer
421 views

Einsteins knights and knaves

For an upcoming major puzzling event, I was honored with the task of creating one of the puzzles which will be presented. I decided to go with a variation of Einstein's puzzle. I selected four ...
1
vote
3answers
615 views

Who broke it. 3 person logic

D walks into a room and sees his computer is broken. He asks "Who broke my computer?". A says B did it B says A is lying C says he did not Of the three, it is known that only one is ...
6
votes
10answers
1k views

Knights and Knaves Puzzle

On the island of knights and knaves, one of the inhabitants says "If I am a knight, then I will eat my hat." Will the inhabitant eat his hat?
25
votes
6answers
5k views

Out of these 20 Doors, Which One Leads You to the Jackpot?

Congratulations for achieving this final stage of "Millionaire Super Logic" show! Once again, my name is Athin, and I'll be your host to help you win the jackpot of one, milLION, DOLLARS! *audience ...
21
votes
6answers
4k views

The Knight never lies, the knave always lies, and the spy either lies or tells the truth

A says he is not the knight, B says he is not a spy, and C says he is not the knave. Who is who?
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 ...
7
votes
6answers
2k views

Contradictional Ceremony Puzzle

Can you find out who is the killer behind this wedding ceremony case? Your friend asked you to attend a wedding ceremony of his younger brother, Mike. The ceremony ran smoothly and lively. Mike and ...
4
votes
5answers
635 views

Who broke Mrs. Smith's kitchen window?

you are a detective in the local neighborhood. Four windows have been broken: the school's window, Mrs. Smith's kitchen window, Mr. Brown's car window, and the police officer's window. The four ...
-1
votes
2answers
240 views

Round tabel conference with liars?

In a conference, 8 People sit in a round table all pointing inwards .They are A,B,C,D,E,F,G and H. 3 people out the 8 people always lie .While others always speaks truth . Here are there 8 ...
32
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. ...
6
votes
3answers
561 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 ...
3
votes
2answers
219 views

Where’s my present?

sequel of: Which of my friends has a birthday today? Hello. It's me again. Today is my birthday! So of course I met my friends today, along with a new friend that I made the other day. This new ...
6
votes
3answers
553 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 ...
4
votes
1answer
307 views

Are all “Who did it?” puzzles the same?

I recently came across this puzzle here and several others not on Stack Exchange, which seem to follow a common pattern I call "Who did it?" for now. "Who did it?" does not refer to any puzzle ...
28
votes
7answers
10k views

Who killed Jeremy?

Jeremy was killed. Peter claims that Tom is guilty. Tom says that Ralph is guilty. John swears he didn't kill Jeremy. Ralph says that Tom is lying. If only one person is telling the ...
-2
votes
3answers
576 views

Which teacher is telling the truth?

It is generally known that lecturers for some course either always tell the truth or always lie. Arthur and Ignaz are those lecturers. Arthur says: "Exactly one of us is lying". Ignaz says: "...
4
votes
5answers
515 views

You meet Yessayer, Nosayer, Truther, Liar

You meet 4 persons you haven't seen before, and must ask questions to determine who is who.They know each other, and their friends' behaviour. You may ask each as many times as you want but only yes/...
9
votes
6answers
4k views

Solve the following knights and knaves problem

A says: “B is a knave.” B says: “A and C are of the same type.” Knights tell the truth and Knaves lie. What is C? (i.e. a knight, or a knave?)
37
votes
3answers
10k views

How many liars are in the room?

There are five people in a room. Each person is either a knight, who always tells the truth, or a liar, who always lies. Each person is asked the following question: How many liars are among you?...
35
votes
12answers
9k views

Batman vs 4 villains

One day after having his morning Bat-coffee, Batman received the following message on his Bat-computer: Hello there Dark Knight. I, the Riddler, along with Joker, Two-Face, and Penguin, are ...
5
votes
1answer
302 views

Four boxes, four questions, only one truthful answer

This is a harder variant of the following question: Three boxes, Four questions, Three times not true, Once the truth The difference is that now there are four (not three) boxes, one of which ...
13
votes
9answers
3k 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 ...
17
votes
4answers
2k views

Can anything be deduced from the statement “If I am a truth teller, the other two are liars”?

There is a scenario which goes along the following lines: There are three friends. The friends are either truth tellers, or liars. One friend makes the statement: "If I am a truth teller, the ...
10
votes
6answers
1k views

Three Doors Logic Puzzle

One day you wake up in a strange room with no windows and three exits (don't ask why, you just do). Between you and the doors is a very moody looking guard who will no doubt kick your ass if you try ...
4
votes
9answers
2k views

Choose the right door for golds

Choose the right door for golds. Do it very carefully. If you choose the wrong door you will be dead.
-5
votes
4answers
356 views

Knights Knaves and Spies

There are inhabitants of an island on which there are three kinds of people: Knights who always tell the truth Knaves who always lie Spies who can either lie or tell the truth. You encounter three ...
3
votes
1answer
962 views

Alternate answer to the 2 guard 2 door question?

I asked a friend the classic question about the two guards and two doors that goes as follows: The rules are clear: there are two doors. One leads to the castle, the other, to certain death. You may ...
3
votes
1answer
504 views

Who lies and who tells the truth?

Six PLK secret agents are arrested and interrogated for several days. An agent tells the truth when all his statements are true, otherwise he lies. A report is drawn up containing the following ...
8
votes
7answers
4k views

Stolen Computer [duplicate]

A retail businessman had his computer stolen. The thief had to be Ruma, Jennifer, Djokovic, Tuhin, or Monisha. When questioned, each executive made three statements: Ruma (a) I didn't take the ...
8
votes
3answers
453 views

Hired by the Council of Magic - Language Barrier at the Circle

Hired by the Council of Magic - Language Barrier at the Circle: After your two successful visits to call upon the aid of the Council of Magic, the Council has called in one of the favors the King of ...
7
votes
4answers
1k views

Knight and knave impostors!

While on some adventure, you are transported away from your companion magically. Your companion, confused, enters a nearby building that suddenly materialised overnight. Inside the building there is ...
6
votes
3answers
759 views

Telling the truth or lying?

There are two men, Bob and Dylan. Bob says “One of the two of us is a liar”. Dylan says “Actually, we’re both liars”. Honest men always tell the truth and liars always lie. What are these men? Both ...
7
votes
2answers
649 views

What did he say he said? Liars with a twist!

5 shy dudes who can never talk for themselves stand in a circle. Every time you ask one of them a question, the dude to their right will answer for them. 3 of them always lie and 2 of them always tell ...
-1
votes
3answers
192 views

Boxed AI, Ethics, and Chivalry, oh my

(Inspired by this somewhat) So, your science lab is on the forefront of super AI. However they may not be on the forefront of good AI. Hence the AI is in a box until they can figure out what to do ...