Riddle

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Mo0o

Lifer
Jul 31, 2001
24,227
3
76
Originally posted by: bradruth
It'd be two days. After the first day nobody would be killed, since each man assumes it's another wife that's unfaithful. The second day each man would assume it's his wife that's unfaithful and would then kill her.

 

ThePresence

Elite Member
Nov 19, 2001
27,727
16
81
Answer:
N = 2, which means there are only 2 wise men.
On the morning of the 2nd day, each one reasons as follows: If my neighbor knows there is only one unfaithful wife, and he didn't kill his own wife, then he assumes that my wife, not his, is unfaithful. He and I are the only ones in this town, so my wife obviously betrayed me with him.

EDIT: This proof works for any N with the help of mathematical induction.
 

walla

Senior member
Jun 2, 2001
987
0
0
Originally posted by: ifoundthetao
why are you trying to figure out how many days? the answer wont be a number. Why will it take as many days to kill all the wives as there are wisemen? I think Godmare is close.


it will take as many days as there are wives.

in the example where N=2, on the first day no wife will be killed since each husband assumes their wifes faithfulness. However, on the second day, a wiseman A will KNOW that if the other man B KNEW that wife A was faithful to man A, he would have killed is own wife B knowing that AT LEAST one of the two wifes was unfaithful. Since both wives are still alive, they can both conclude that their wives are unfaithful.

This extends to N.
 

Mo0o

Lifer
Jul 31, 2001
24,227
3
76
Originally posted by: ThePresence
In the town of X there are N families. All the husbands in town are wise men, and they spend their mornings thinking. Every afternoon they implement their decisions. All of the wives in this town are unfaithful. There is a rule in town that if a husband should learn that his wife is unfaithful, he kills her that day. But while each husband knows about the unfaithfulness of all the other wives, he believes his own wife is an exception.

One day a traveler arrives, looks around, and announces "there is an unfaithful wife in this town". Although the traveler imparts no new information, in exactly N days all N wives are killed by their husbands. Explain why.

Answer:
N = 2, which means there are only 2 wise men.
On the morning of the 2nd day, each one reasons as follows: If my neighbor knows there is only one unfaithful wife, and he didn't kill his own wife, then he assumes that my wife, not his, is unfaithful. He and I are the only ones in this town, so my wife obviously betrayed me with him.

:confused:
 

ThePresence

Elite Member
Nov 19, 2001
27,727
16
81
Originally posted by: Mo0o
Originally posted by: ThePresence
In the town of X there are N families. All the husbands in town are wise men, and they spend their mornings thinking. Every afternoon they implement their decisions. All of the wives in this town are unfaithful. There is a rule in town that if a husband should learn that his wife is unfaithful, he kills her that day. But while each husband knows about the unfaithfulness of all the other wives, he believes his own wife is an exception.

One day a traveler arrives, looks around, and announces "there is an unfaithful wife in this town". Although the traveler imparts no new information, in exactly N days all N wives are killed by their husbands. Explain why.

Answer:
N = 2, which means there are only 2 wise men.
On the morning of the 2nd day, each one reasons as follows: If my neighbor knows there is only one unfaithful wife, and he didn't kill his own wife, then he assumes that my wife, not his, is unfaithful. He and I are the only ones in this town, so my wife obviously betrayed me with him.

:confused:

Oh come on. 2 can be all.
 

bradruth

Lifer
Aug 9, 2002
13,479
2
81
Originally posted by: ThePresence
Originally posted by: Mo0o
Originally posted by: ThePresence
In the town of X there are N families. All the husbands in town are wise men, and they spend their mornings thinking. Every afternoon they implement their decisions. All of the wives in this town are unfaithful. There is a rule in town that if a husband should learn that his wife is unfaithful, he kills her that day. But while each husband knows about the unfaithfulness of all the other wives, he believes his own wife is an exception.

One day a traveler arrives, looks around, and announces "there is an unfaithful wife in this town". Although the traveler imparts no new information, in exactly N days all N wives are killed by their husbands. Explain why.

Answer:
N = 2, which means there are only 2 wise men.
On the morning of the 2nd day, each one reasons as follows: If my neighbor knows there is only one unfaithful wife, and he didn't kill his own wife, then he assumes that my wife, not his, is unfaithful. He and I are the only ones in this town, so my wife obviously betrayed me with him.

:confused:

Oh come on. 2 can be all.

He's right. It can.
 

Mo0o

Lifer
Jul 31, 2001
24,227
3
76
Originally posted by: bradruth
Originally posted by: ThePresence
Originally posted by: Mo0o
Originally posted by: ThePresence
In the town of X there are N families. All the husbands in town are wise men, and they spend their mornings thinking. Every afternoon they implement their decisions. All of the wives in this town are unfaithful. There is a rule in town that if a husband should learn that his wife is unfaithful, he kills her that day. But while each husband knows about the unfaithfulness of all the other wives, he believes his own wife is an exception.

One day a traveler arrives, looks around, and announces "there is an unfaithful wife in this town". Although the traveler imparts no new information, in exactly N days all N wives are killed by their husbands. Explain why.

Answer:
N = 2, which means there are only 2 wise men.
On the morning of the 2nd day, each one reasons as follows: If my neighbor knows there is only one unfaithful wife, and he didn't kill his own wife, then he assumes that my wife, not his, is unfaithful. He and I are the only ones in this town, so my wife obviously betrayed me with him.

:confused:

Oh come on. 2 can be all.

He's right. It can.

oh ok right on.
 
Jan 18, 2001
14,465
1
0
so after the traveler makes his announcement, each husband contemplates who the cheater is. He begins systematically seducing 1 woman per day, but the women, knowing that this would result in their death, they refuse the men.

Day 1...pick a woman to seduce, and spend the afternoon trying, but failing, to seduce her (all wives know that if they sleep around they will be killed and thus refuse all propositions).
Day 2...ditto
...
Day N-1...pick last woman (other than wife), spend afternoon failing to seduce her.

Day N. based on elimination, each man decides that it must be his wife that is unfaithful, and later that afternoon all the wives are murdered.
 

ThePresence

Elite Member
Nov 19, 2001
27,727
16
81
Originally posted by: HomeBrewerDude
so after the traveler makes his announcement, each husband contemplates who the cheater is. He begins systematically seducing 1 woman per day, but the women, knowing that this would result in their death, they refuse the men.

But they are all unfaithful. That's a fact.
 

RaynorWolfcastle

Diamond Member
Feb 8, 2001
8,968
16
81
Originally posted by: HomeBrewerDude
so after the traveler makes his announcement, each husband contemplates who the cheater is. He begins systematically seducing 1 woman per day, but the women, knowing that this would result in their death, they refuse the men.

Day 1...pick a woman to seduce, and spend the afternoon trying, but failing, to seduce her (all wives know that if they sleep around they will be killed and thus refuse all propositions).
Day 2...ditto
...
Day N-1...pick last woman (other than wife), spend afternoon failing to seduce her.

Day N. based on elimination, each man decides that it must be his wife that is unfaithful, and later that afternoon all the wives are murdered.

All nice and good but under this scenario it is assumed that the unfaithful wife will cheat with anyone. If this isn't assumed then you cannot follow that logical chain because each husband can only conclude that no wife cheated with him.
 
Jun 4, 2005
19,723
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I think it's retarded to make the assumption that there are only two men in the village. That changes everyone's answeres dramatically thus changing the outcome of the puzzle. That riddle is based on the hopes that the person attempting to solve it will use some common sense, and not cheat and assume there are so few people.
 

ThePresence

Elite Member
Nov 19, 2001
27,727
16
81
Originally posted by: LoKe
I think it's retarded to make the assumption that there are only two men in the village. That changes everyone's answeres dramatically thus changing the outcome of the puzzle. That riddle is based on the hopes that the person attempting to solve it will use some common sense, and not cheat and assume there are so few people.

How is 2 cheating??????????????
 
Jun 4, 2005
19,723
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I explained it. A person would logically assume a civilisation would consist of more than four people, thus making the answer different.
 

ThePresence

Elite Member
Nov 19, 2001
27,727
16
81
Originally posted by: LoKe
I explained it. A person would logically assume a civilisation would consist of more than four people, thus making the answer different.

There is no mathematical reason to assume that.
 

chuckywang

Lifer
Jan 12, 2004
20,133
1
0
You need to explain it better. Why should the husband believe his neighbor that his own wife is unfaithful?
 
Jun 4, 2005
19,723
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Originally posted by: lobadobadingdong
That wasn't a riddle...it was a math problem.

That's more or less my point.

The people answering this riddle weren't necessarily mathematicians, naturally we'd assume the most probably scenario, there are many people in the village.
 

ThePresence

Elite Member
Nov 19, 2001
27,727
16
81
Originally posted by: LoKe
Originally posted by: lobadobadingdong
That wasn't a riddle...it was a math problem.

That's more or less my point.

The people answering this riddle weren't necessarily mathematicians, naturally we'd assume the most probably scenario, there are many people in the village.

I think it was quite evident from the nature of the question that it was a math problem.
 
Jun 4, 2005
19,723
1
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Hardly, it looked like a more logical riddle.

I'm not saying anything against you, for you didn't write the riddle, but more towards the classification of the riddle.