Fun Reasoning Puzzle - King and Prisoner - China DOS Union Forum

The king wants to execute a prisoner but gives him a chance to survive.
The prisoner is led to 5 closed doors, and one of them has a tiger behind it.
The king says to the prisoner: "You must open these doors in sequence. I can be certain that you won't know where the tiger is until you open the door that has the tiger behind it."
Before opening the doors, the prisoner made the following analysis:
1. Suppose the tiger is behind the 5th door, then after I open the first 4 doors, I will already know that the tiger is behind the 5th door, which contradicts the king's words.
=> The tiger can only be behind the first 4 doors.
2. Suppose the tiger is behind the 4th door, then after I open the first 3 doors, I will already know that the tiger is behind the 4th door, which contradicts the king's words.
=> The tiger can only be behind the first 3 doors.
3. By analogy.
=> There is no tiger!
The prisoner thought the king was scaring him and there was no tiger at all. So he confidently went to open the doors. But when he opened the 2nd door, the tiger jumped out and ate him.
The prisoner's reasoning seemed very rigorous. But the king's words also seemed correct: the prisoner really didn't know that the tiger was behind the 2nd door before opening it.
What on earth is going on?

This isn't too long, right? Hehe... Is there anyone who has figured it out???

Heh, I guess every door has its own tiger!!

He forgot one condition, that is, the situation where there are no tigers behind all five doors. His reasoning was carried out under the condition that there were tigers, but his final implementation added this condition, so his first reasoning was wrong from the beginning. Even if there are no tigers behind the first four doors, he can't judge whether there is a tiger behind the fifth door.

But the king said there must be a tiger~
Did the prisoner's first reasoning have a mistake?? He assumed the tiger was behind the fifth door, but the king said the tiger could only be behind the first four doors.
As long as the prisoner assumes a tiger is behind a door, the king said it must be behind one of the doors in front of the one he assumed. So the prisoner's final conclusion was also not wrong~~
But when he opened the second door, the tiger came out, so it should be that there is a tiger behind each door

DD, you didn't read the question clearly. There is only one tiger. Because the prisoner's answer is something that wasn't considered in his reasoning process. That is to say, he thought there was no tiger, in fact he admitted this condition, but he didn't consider this condition when reasoning, so his whole reasoning was wrong. What you said that there is a tiger behind each door is even less possible, because he was eaten by the tiger behind the second door. The question has said that there is no tiger behind the first door.

Strange, does the question say that there is no tiger behind the first door??
If it's because he was eaten behind the second door and then saying there's no tiger behind the first door, that's not right either!! It should be that there are no tigers behind the subsequent doors~~ Then the answer would be clear~~ So why ask??
Yes, the prisoner indeed didn't include the condition of "no tiger" in the reasoning, but the king said there must be a tiger at the beginning, so the prisoner didn't include the "no tiger" condition~~
And the prisoner didn't think there was "no tiger" at the beginning either~

How can I make it clear to you? Let's put it this way. The prisoner's conclusion is that there is no tiger, but precisely because the conclusion is no tiger, then his previous reasoning can't hold water, because his reasoning is deduced according to the situation of there being a tiger, that is, his reasoning must be valid only if there is a tiger, and the conclusion must not be no tiger. Otherwise, if he admits there is no tiger, the condition of there being a tiger is not established, and the whole reasoning is completely invalid. In fact, this conclusion of no tiger is both a conclusion and a condition. So he has to continue reasoning.

The prisoner should reason like this:
1. Assume the tiger is behind the 5th door, then after I open the first 4 doors, I will already know the tiger is behind the 5th door, which contradicts the king's words.
=> The tiger can only be behind the first 4 doors.
2. Assume the tiger is behind the 4th door, then after I open the first 3 doors, I will already know the tiger is behind the 4th door, which contradicts the king's words.
=> The tiger can only be behind the first 3 doors.
3. By analogy.
=> There is no tiger!
4. There is no tiger.
But if the king puts the tiger in the first door, because my conclusion is no tiger, so I don't know there is a tiger.
If the king puts the tiger in the second door, because my conclusion is no tiger, so I also don't know there is a tiger.
......
By analogy
The king puts the tiger in any door, the prisoner can't know there is a tiger before opening it, so the prisoner is doomed to die.
From another perspective, this reasoning is actually a vicious circle, that is, there is a tiger - no tiger - there is a tiger -...
That is, condition - conclusion (condition) - conclusion (condition) -...
So the final conclusion is that there is no way to reason, and the prisoner waits to die.

Assuming there are no tigers ahead during reasoning is problematic in itself. Because there must be a tiger ahead, and if the tiger eats the prisoner, there won't be the subsequent certainty.

The king's words "You must open these doors in sequence. I can be sure that you won't know where the tiger is behind until you open the door that has the tiger closed." will make people think in the direction that there must be a tiger~~
And at the beginning, no one would think with "there is no tiger" right?

His reasoning was not wrong at first, but rather that the reasoning itself is contradictory. Don't you understand? It's that the condition of having a tiger and the conclusion of not having a tiger are contradictory. It's precisely because of the conclusion of not having a tiger that the previous condition of having a tiger is overthrown, so the entire reasoning is overthrown. I think what I said is clear enough.
KO, you don't come out to announce the answer, just us arguing here aimlessly.

yiyesong is powerful. He said everything I wanted to say. Then what else should I read for?

This issue is fun just because of the debate.

Dizzy... Originally it was a debate topic~~

Floor1　ko20010214	Posted 2003-06-15 00:00
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The king wants to execute a prisoner but gives him a chance to survive. The prisoner is led to 5 closed doors, and one of them has a tiger behind it. The king says to the prisoner: "You must open these doors in sequence. I can be certain that you won't know where the tiger is until you open the door that has the tiger behind it." Before opening the doors, the prisoner made the following analysis: 1. Suppose the tiger is behind the 5th door, then after I open the first 4 doors, I will already know that the tiger is behind the 5th door, which contradicts the king's words. => The tiger can only be behind the first 4 doors. 2. Suppose the tiger is behind the 4th door, then after I open the first 3 doors, I will already know that the tiger is behind the 4th door, which contradicts the king's words. => The tiger can only be behind the first 3 doors. 3. By analogy. => There is no tiger! The prisoner thought the king was scaring him and there was no tiger at all. So he confidently went to open the doors. But when he opened the 2nd door, the tiger jumped out and ate him. The prisoner's reasoning seemed very rigorous. But the king's words also seemed correct: the prisoner really didn't know that the tiger was behind the 2nd door before opening it. What on earth is going on?

Floor2　西西	Posted 2003-06-15 00:00
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Still this long?

Floor3　ko20010214	Posted 2003-06-15 00:00
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This isn't too long, right? Hehe... Is there anyone who has figured it out???

Floor4　Dark-Destroy	Posted 2003-06-16 00:00
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Heh, I guess every door has its own tiger!!

Floor5　yiyesong	Posted 2003-06-16 00:00
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He forgot one condition, that is, the situation where there are no tigers behind all five doors. His reasoning was carried out under the condition that there were tigers, but his final implementation added this condition, so his first reasoning was wrong from the beginning. Even if there are no tigers behind the first four doors, he can't judge whether there is a tiger behind the fifth door.

Floor6　Dark-Destroy	Posted 2003-06-16 00:00
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But the king said there must be a tiger~ Did the prisoner's first reasoning have a mistake?? He assumed the tiger was behind the fifth door, but the king said the tiger could only be behind the first four doors. As long as the prisoner assumes a tiger is behind a door, the king said it must be behind one of the doors in front of the one he assumed. So the prisoner's final conclusion was also not wrong~~ But when he opened the second door, the tiger came out, so it should be that there is a tiger behind each door

Floor7　yiyesong	Posted 2003-06-16 00:00
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DD, you didn't read the question clearly. There is only one tiger. Because the prisoner's answer is something that wasn't considered in his reasoning process. That is to say, he thought there was no tiger, in fact he admitted this condition, but he didn't consider this condition when reasoning, so his whole reasoning was wrong. What you said that there is a tiger behind each door is even less possible, because he was eaten by the tiger behind the second door. The question has said that there is no tiger behind the first door.

Floor8　Dark-Destroy	Posted 2003-06-16 00:00
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Strange, does the question say that there is no tiger behind the first door?? If it's because he was eaten behind the second door and then saying there's no tiger behind the first door, that's not right either!! It should be that there are no tigers behind the subsequent doors~~ Then the answer would be clear~~ So why ask?? Yes, the prisoner indeed didn't include the condition of "no tiger" in the reasoning, but the king said there must be a tiger at the beginning, so the prisoner didn't include the "no tiger" condition~~ And the prisoner didn't think there was "no tiger" at the beginning either~

Floor9　szwy	Posted 2003-06-16 00:00
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How can I make it clear to you? Let's put it this way. The prisoner's conclusion is that there is no tiger, but precisely because the conclusion is no tiger, then his previous reasoning can't hold water, because his reasoning is deduced according to the situation of there being a tiger, that is, his reasoning must be valid only if there is a tiger, and the conclusion must not be no tiger. Otherwise, if he admits there is no tiger, the condition of there being a tiger is not established, and the whole reasoning is completely invalid. In fact, this conclusion of no tiger is both a conclusion and a condition. So he has to continue reasoning. The prisoner should reason like this: 1. Assume the tiger is behind the 5th door, then after I open the first 4 doors, I will already know the tiger is behind the 5th door, which contradicts the king's words. => The tiger can only be behind the first 4 doors. 2. Assume the tiger is behind the 4th door, then after I open the first 3 doors, I will already know the tiger is behind the 4th door, which contradicts the king's words. => The tiger can only be behind the first 3 doors. 3. By analogy. => There is no tiger! 4. There is no tiger. But if the king puts the tiger in the first door, because my conclusion is no tiger, so I don't know there is a tiger. If the king puts the tiger in the second door, because my conclusion is no tiger, so I also don't know there is a tiger. ...... By analogy The king puts the tiger in any door, the prisoner can't know there is a tiger before opening it, so the prisoner is doomed to die. From another perspective, this reasoning is actually a vicious circle, that is, there is a tiger - no tiger - there is a tiger -... That is, condition - conclusion (condition) - conclusion (condition) -... So the final conclusion is that there is no way to reason, and the prisoner waits to die.

Floor10　boyachang	Posted 2003-06-16 00:00
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Assuming there are no tigers ahead during reasoning is problematic in itself. Because there must be a tiger ahead, and if the tiger eats the prisoner, there won't be the subsequent certainty.

Floor11　Dark-Destroy	Posted 2003-06-16 00:00
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The king's words "You must open these doors in sequence. I can be sure that you won't know where the tiger is behind until you open the door that has the tiger closed." will make people think in the direction that there must be a tiger~~ And at the beginning, no one would think with "there is no tiger" right?

Floor12　yiyesong	Posted 2003-06-16 00:00
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His reasoning was not wrong at first, but rather that the reasoning itself is contradictory. Don't you understand? It's that the condition of having a tiger and the conclusion of not having a tiger are contradictory. It's precisely because of the conclusion of not having a tiger that the previous condition of having a tiger is overthrown, so the entire reasoning is overthrown. I think what I said is clear enough. KO, you don't come out to announce the answer, just us arguing here aimlessly.

Floor13　如是大师	Posted 2003-06-17 00:00
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yiyesong is powerful. He said everything I wanted to say. Then what else should I read for?

Floor14　ko20010214	Posted 2003-06-17 00:00
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This issue is fun just because of the debate.

Floor15　Dark-Destroy	Posted 2003-06-18 00:00
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Dizzy... Originally it was a debate topic~~