Logical riddle

Logic riddles are pastimes or games that consist of finding the solution to an enigma or finding the hidden meaning of a sentence only through intuition and reasoning, and not by virtue of possession of certain knowledge. The difference with riddles is that these pose the enigma in the form of a rhyme and are generally aimed at children.

As for all logic puzzles, a logic puzzle should have a mathematical or logical basis. However, riddles that once solved reveal a more or less humorous nature are widespread. For example, due to the fact that they are based on puns or due to the way in which the statement is proposed. A more or less typical scheme consists of presenting a paradoxical situation and asking the participant how it is possible for this situation to occur.

To solve the most common riddles you have to use your imagination and the ability to deduce. The resolution has to be given with the mere statement of the statement, so questions are not allowed.

A fundamental subdivision in logic puzzles are yes-or-no puzzles in which the initial information provided is incomplete. In this category, the riddle based on paradoxes must be solved. In them, an atypical situation is described and the participants, through questions, must discover the origin of it. The person who proposes it can only answer yes or no to the questions that are asked, so these must be very specific. It is important to make it known at the beginning that the solutions cannot be found by deduction, so it will be necessary to ask several questions to reach the correct answer.

Classic Riddles

Paradoxical riddles

The most common puzzles reflect situations in which an unusual event or result has occurred and the cause must be found. Here are some of the many existing examples:

1. A cowboy came to a town with his horse and arrived on Friday and stayed a day and then left on Friday, how did he do it?
3. A man appears hanged in his cell without any support under his feet. Both the door and the window are locked inside, and there is no other way out. There's no other furniture in the room. How did you do it?
4. A bridge holds only a thousand kilos of weight, from which it sinks irremediably. A truck weighs exactly a thousand pounds when it enters the bridge. Halfway through, a feather sits softly on it but the bridge doesn't sink. Why?
5. By turning off a forest fire, a hydroplane collects water at sea. Then they discover the horned body of a diver. Why?
6. How many grooves have an audio record? A vinyl disc, you understand.
7. A pilot has a mission. You must fly with your plane and drop a bomb on a certain point. The whole device has been revised and works perfectly. Upon arrival at destination, trigger commands but the bomb doesn't fall. Why?
8. A gentleman lives on the eighth floor of a building. Every day he climbs up the elevator to the room and then climbs the remaining four stairs, except when it rains. Why?
9. Three women appear in a swimsuit. One is happy but weep. The other two are sad but smile. Why?
10. A king is about to die and calls his two sons, big horse enthusiasts. The king tells them that he will inherit the kingdom that proves that he has the horse that later came to the ends of the kingdom and return. One of them decides to pass the days and the other, after consulting a wise man of the kingdom, takes a horse and goes out to the gallop. In the end, this is the one who inherits the kingdom. Why?

Solutions

1. The horse is called "Friday" as the "in" preposition tells you.
2. He went up to an ice block that became water that, in turn, evaporated./ No one has said that he would have tied the rope to the ceiling... I could have tied her to the bars in the cell.
3. He's consumed some of his gas so he weighs less than when he came in.
4. The hydroplane that collected water from the lake to quench the fire hooked it and threw it into the forest.
5. Two: one for each face.
6. The plane flies upside down.
7. The master is dwarf and only presses the fourth floor button, but when it rains you can press the eighth button with the tip of the umbrella.
8. It is a beauty contest; the one that has won weeps, those who have lost it congratulating smiling.
9. The prince who goes out to the gallop has taken a horse from his brother's block.

Cheating or pun

Some riddles are simple entertainment games that contain a little trap consisting of expressions with double meanings or puns. Their advantage is that they are brief and do not require prior announcement, so they can be raised at any time during a conversation.

1. This bank is occupied by a father and a son, the father is called John and the son has told him.
2. How many apricots would you be able to eat in fasts?
3. How many times can you take six to 36?
4. What sheep give more wool, white or black?
5. A building has seven floors that are called the days of the week: Monday, Tuesday, Wednesday, etc. What will you call the elevator?

Solutions

1. Esteban, Joel or Joseph.
2. Generally, an amount greater than one will be answered. You mean one. The rest, you won't take them fast anymore.
3. Generally, 6 will be answered. Just one. Next you take it off at 30.
4. The white ones, because there's more.
5. With the button, like everyone else.

Propositional Logic Riddles

Riddles that are based on propositional logic challenge the viewer to get the correct answer from a set of sentences, which can be true or false depending on the conditions of the riddle itself.

Special mention are the puzzles based on different characters or objects that are assumed to be telling the truth or lying. The most popular variant is the one known as "Knights and Knaves" (where the knights always tell the truth and the squires always lie), although we can find other characters such as zombies, vampires, chests or unicorns. Each character of these can also carry another condition that makes the riddle itself difficult, for example: "unicorns lie Monday, Wednesday and Friday" or "the inscription on the chest is half erased so we dont know what it says".

As a reference author of logic puzzles we can highlight the figure of Raymond Smullyan, who in his work deals with all the casuistry of this variant of recreational logic.

The following are some examples that illustrate this type of riddle:

1. In a prison we must leave, there are two doors. One leads to the exit. The other one, to safe death. Each door is guarded by a guardian. We know that one of them always tells the truth and that the other lies always, but we do not know what each one is. The question is: if you could ask only one question to one of the two, what question would you ask him to know which door is the good one?
2. A visitor finds three inhabitants of the island of the knights and squids (an island where the knights always tell the truth and the squids always lie). He approaches the first and asks, "Are you a gentleman or a squire?" This answer, but the visitor doesn't understand him well. For his part, the second says, "He said he's squire." And the third apostolate: "That's a lie." What are the second and third inhabitants?
3. We have 4 chests and inside one there is a treasure. Each chest contains an inscription and we know that 2 tell the truth and 2 lie. Where's the treasure?
   • Box 1: The treasure is not here.
   • Box 2: The chest 1 says the truth.
   • Box 3: Treasure is not in the chest 2.
   • Box 4: The chest 3 is empty.

Solutions

1. The question I would ask you is, "What's the door your partner would say is the right one?". In any case, the answer will be false.
2. No one can say of himself that he is squire, since, if he is a gentleman, he must tell the truth and, if he is squire, he will also say that he is a gentleman because he lies always. Therefore, the second inhabitant lies: he is squire. And, the third, says the truth, therefore, is a gentleman.
3. For two to be fulfilled to tell the truth and two lie, the treasure must be in the chest 1

Yes or no riddles

As said before, these are riddles in which participants must ask questions (yes or no) until they find the solution. Here are some examples:

1. A man walks through the desert. Get to a drink stand and order a glass of water. The waiter, instead of giving it to him, points to him with a gun. The traveler says "Thank you!" and he's on his way.
2. A dead man appears in the middle of the desert and with a match in his hand.
3. An Englishman receives a package, opens it and smiles. He closes it and, in turn, sends it to a Frenchman, who opens it and smiles. He closes it and sends it, like, to an Italian, who does the same thing. At the end of time, the Italian finds the fourth friend at an airport, which when he comes down from the plane greets him with his hand. Immediately, he kills him.
4. A man is thrown down the balcony with intent to kill himself. When he walks through a floor he hears a phone and repents.
5. A man opens the door, lowers the stairs and dies.
6. Marco Antonio and Cleopatra lived happily. Someone came in, opened the window and both died.
7. Joseph and Mary are dead on the floor of a room next to the bed with water and broken glass.

Solutions

1. The walker has no thirst but hypo. That's why he asks for a glass of water. By pointing at him with the gun he disappears the hypo of the scare, which he appreciates
2. Several travelers fly in a balloon. Suddenly, a breakdown occurs so the ladder should be released. Little by little, they throw all the luggage, including their clothes. When there's nothing left, someone has to jump and draw him for the matches game. The one who takes the shortest is the one chosen
3. A shipwreck and only four shipwrecks remain that are the protagonists of history. When they run out of food, they're gonna get one to cut his arm to eat it. That's how English does it. Then it's the Frenchman and later the Italian. Before we do the room, they're rescued. Then, they agree that he will amputate his arm in fate and send it to his friends to prove it. The day the Italian finds him at the airport, he understands that it was not his arm that sent them for what kills him.
4. There's been a nuclear hecatombe on earth with a survivor. Seeing himself alone in the world, he decides to commit suicide. However, he hears a phone so he understands that there is someone more alive and repents
5. It's an astronaut. He has reached an atmosphereless planet and there is a leak in his suit so he suffocates.
6. Marco Antonio and Cleopatra were two fish living in their fish. When the window opened, the fish fell to the ground and died asphyxiated.
7. Joseph and Mary were two fish that were in their fish. But there was an earthquake and they fell to the ground.