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Monty Hall, we have a PROBLEM

Isn't there a scenario where you ask a liar if he/she is telling the truth and if they say No, it's the truth, but they can't tell the truth so they end up in an infinite loop?

Yes and Norman self-destructs just working it out :).
 
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Re: Monty Hall, we have a PROBLEM

Isn't there a scenario where you ask a liar if he/she is telling the truth and if they say No, it's the truth, but they can't tell the truth so they end up in an infinite loop?

You're arrested, thrown in jail, and given the death penalty.

The executioner, however, allows you to make one final statement in your last words. If it is a true statement, you'll be hanged. If it is false, you'll be beheaded.

Your statement should be "You're going to behead me." He would have to behead you to make it true, which means he should have hanged you instead. If he hangs you, then it was a false statement and he should have beheaded you instead.
 
Isn't there a scenario where you ask a liar if he/she is telling the truth and if they say No, it's the truth, but they can't tell the truth so they end up in an infinite loop?

Yes and Norman self-deconstructs just working it out :).
 
Re: Monty Hall, we have a PROBLEM

You're arrested, thrown in jail, and given the death penalty.

The executioner, however, allows you to make one final statement in your last words. If it is a true statement, you'll be hanged. If it is false, you'll be beheaded.

Your statement should be "You're going to behead me." He would have to behead you to make it true, which means he should have hanged you instead. If he hangs you, then it was a false statement and he should have beheaded you instead.
Very similar to Pinocchio saying "My nose will grow now!"
 
Re: Monty Hall, we have a PROBLEM

I have some reservations about Twitch Boy's auction, in white, in case anyone hasn't read his explanation:

In the abscence of spite, the key is that you only bid $99 if you're the *first* bidder. Even if the other guy has only bid $1 before your $99 bid, it would still be in his best interest to go ahead and bid $100 to improve his net position by $1 (form $1 lost to breaking even). In the real world, I wouldn't bid $99 even on the first bid with a 10-foot pole. Even if there's only a 0.0001% chance that there's a spiteful bidder in the room, throwing your hat into the ring at all exposes you to a huge potential loss, because as soon as the second bidder goes to $100, the infinite loop begins where bidding higher is not spiteful but is actually in both of your own self interests. Even if there's only that 0.0001% chance of a truly spiteful bidder, I guarantee there's at least a 10% chance of a moronic bidder who would bid $100 not out of spite but because he didn't know any better. :) Therefore, the optimal bid is not to bid at all.
 
Re: Monty Hall, we have a PROBLEM

The only winning move is not to play.
 
Re: Monty Hall, we have a PROBLEM

I have some reservations about Twitch Boy's auction

Reminds me of that childhood game, "let's have a contest to see who can hit each other the softest. You go first." ;)


When I hear / read about stuff parents of young children worry about today, I'm amazed that any of my peers and me made it to adulthood!
 
Re: Monty Hall, we have a PROBLEM

you ask a liar if he/she is telling the truth and if they say "no"...

ah but they'd never answer "no" in the first place, would they? They'd more likely respond with "I always tell the truth" or some other such non-truthful evasion.

I'll skip all the obvious political jokes too.
 
I agree. Owslachiefs answer is also "correct" in that it will give you the information you seek in this particular problem. The problem statement gives you 3 key pieces of information:

1) there is a truth teller
2) there is a liar
3) the truth teller is in front of the heaven door (so the liar is in front of the other).

Given those 3 pieces of info, owslachef's answer works perfectly. I've seen a similar problem statement that omitted item #3 above: the guardians are just standing together, off to the side, and not associated with either door. In that case, owslachef's answer doesn't work - his question will tell you which is the liar and which is the truth teller, but then you would need to ask a second question to find out which door to choose, as that information is not "linked" to which guardian is which. The answer I gave works whether the guardians are associated with the doors or not.

Interestingly, if the guardians are not assigned to particular doors and you ask the question I gave, you would be able to choose the correct door, but you would still *not* be able to identify which guardian was the liar.

My bad on that. Didn't really read it as I assumed it was the version I had seen before in which #3 was not a given.
 
Re: Monty Hall, we have a PROBLEM

This statement is false.

So you say...but how reliable are you? did you discover that truth on your own, or is it from sometihing you read on the internet and re-posted without checking its validity first? ;)
 
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Re: Monty Hall, we have a PROBLEM

Something about this thread reminds me of the story of Carl Friedrich Gauss as an elementary school student. Even at that age, he knew more than his teacher.

His harried teacher finally thought of a way to quiet the precocious child. "Add the numbers from 1 to 100" he instructed, hoping to gain a few moments' respite from the child's unrelenting questions.

"Oh, that's easy," supposedly replied the young Gauss. "You take 1+99, 2+98, 3+97, ... and that get's you to 4,900. Add 50 to get 4,950. Then it depends upon whether you said '1 to 100' or '1 through 100' which would make it 5,050."
 
Re: Monty Hall, we have a PROBLEM

If I were you and you were me and I shot you...who would die?

There is a verifiable answer, but it must be phrased correctly.
 
Re: Monty Hall, we have a PROBLEM

I have some reservations about Twitch Boy's auction, in white, in case anyone hasn't read his explanation:

In the abscence of spite, the key is that you only bid $99 if you're the *first* bidder. Even if the other guy has only bid $1 before your $99 bid, it would still be in his best interest to go ahead and bid $100 to improve his net position by $1 (form $1 lost to breaking even). In the real world, I wouldn't bid $99 even on the first bid with a 10-foot pole. Even if there's only a 0.0001% chance that there's a spiteful bidder in the room, throwing your hat into the ring at all exposes you to a huge potential loss, because as soon as the second bidder goes to $100, the infinite loop begins where bidding higher is not spiteful but is actually in both of your own self interests. Even if there's only that 0.0001% chance of a truly spiteful bidder, I guarantee there's at least a 10% chance of a moronic bidder who would bid $100 not out of spite but because he didn't know any better. :) Therefore, the optimal bid is not to bid at all.
http://www.heretical.com/pound/dollar.html
 
You're arrested, thrown in jail, and given the death penalty.

The executioner, however, allows you to make one final statement in your last words. If it is a true statement, you'll be hanged. If it is false, you'll be beheaded.

Your statement should be "You're going to behead me." He would have to behead you to make it true, which means he should have hanged you instead. If he hangs you, then it was a false statement and he should have beheaded you instead.

Another paradoxical scenario was used (unsuccessfully) by the doomed right after sentencing. A creative judge handed him an unusual sentence: he was to be executed during a one-week window, and the day of his execution was to be a surprise.

The man reasoned his salvation as follows: if I survive until the last day, next Friday, then I know it's Friday i'm to die, and it's no longer a surprise. So I can't die on Friday. Thursday then becomes the last possible day, but then the same reasoning applies as for Friday! Safe in the knowledge that he can inductively apply that back through the entire week, he serenely waited out the week, until Friday came. In the morning, the executioner arrived, to the doomed man's complete surprise.
 
Xml Something about this thread reminds me of the story of Carl Friedrich Gauss as an elementary school student. Even at that age, he knew more than his teacher.

His harried teacher finally thought of a way to quiet the precocious child. "Add the numbers from 1 to 100" he instructed, hoping to gain a few moments' respite from the child's unrelenting questions.

"Oh, that's easy," supposedly replied the young Gauss. "You take 1+99, 2+98, 3+97, ... and that get's you to 4,900. Add 50 to get 4,950. Then it depends upon whether you said '1 to 100' or '1 through 100' which would make it 5,050."[/QUOTE]

Yep the 100 x (avg. of #s between 1 and 99, which is 50)
 
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Re: Monty Hall, we have a PROBLEM

There are all kinds of series like that. Adding numbers = n(n+1)/2; the square of n is the summation (x = 1 to n) of 2x-1; so on and so forth.

Here's an interesting problem: On a site called moola.com, there is a game called Gold Rush. The idea is that you get "gold bars" weighed from 1 to 6, as does your opponent. Bars from 1 to 6 are up for grabs in each round. Whomever puts down the highest weight takes the round's pot. Ties put everything into the pot and carries over to the next round. How do you get yourself to win that?
 
Re: Monty Hall, we have a PROBLEM

You're at a party. I'll bet you $100 that at least two of the people in the room share a birthday.

How many people would need to be present for it to be an unfavorable bet for you?

Just 23. At 23 it's about a 50/50 shot that there will be a matching birthday. At 30 there's about a 70% chance of a match. At 50 it's a 97% chance.

Imagine it this way: the guests enter one at a time and state their birthday. If anyone repeats a birthday...THE ROOM EXPLODES!

First guest = can be any date. 365/365 odds of no match. (Assuming no leap years.)
Second guest = has to dodge the first date. 365/365 * 364/365 odds of no match.
Third guest = has to dodge the first and second dates. 365/365 * 364/365 * 363/365 odds of no match.
...
Tenth guest = has to dodge nine dates. 365/365 * 364/365 * ... * 356/365 odds of no match.
...
Twentieth guest = has to dodge NINETEEN dates. 365/365 * 364/365 * ... * 346/365 odds of no match.

It may seem like only a few days to dodge, but try dodging them 23 times in a row. Or 30. Or 50.
 
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