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Subject: Re: New and final solution of the Monty Hall Dilemma

Author: Gerrit Reubold

Date: 13:25:54 09/27/02

Go up one level in this thread


On September 27, 2002 at 16:14:08, Uri Blass wrote:

>On September 27, 2002 at 15:47:15, Peter Berger wrote:
>
>>On September 27, 2002 at 15:27:35, Uri Blass wrote:
>>
>>>On September 27, 2002 at 15:18:52, Peter Berger wrote:
>>>
>>>>On September 27, 2002 at 15:11:12, Uri Blass wrote:
>>>>
>>>>>On September 27, 2002 at 14:58:25, Peter Berger wrote:
>>>>>
>>>>>>On September 27, 2002 at 14:33:22, Uri Blass wrote:
>>>>>>
>>>>>>>Correction:
>>>>>>>I meant one and only one of us is right if incredible luck happened.
>>>>>>>of course in most cases we will discover that both of us wrong.
>>>>>>>
>>>>>>>Uri
>>>>>>
>>>>>>Read http://www.talkchess.com/forums/1/message.html?254769 . I am your friend on
>>>>>>g5 :).
>>>>>>
>>>>>>Peter
>>>>>
>>>>>I read it and replied it without the friend.
>>>>>simulation prove that out of 64000 games
>>>>>only 2000 are practically played and
>>>>>I win 1000 out of 2000 by not switching.
>>>>>
>>>>>With the friend I get the same and I see no reason to prefer a1 and not g5 if I
>>>>>know that the host does not choose g5.
>>>>>
>>>>>If the host choose random squares the game is
>>>>>practically the same because all the squares are the same
>>>>>from the host point of view when he knows nothing about them.
>>>>>
>>>>>Uri
>>>>
>>>>The right assumption IMHO is not that the friend sits on g5 but that the friend
>>>>always sits on the other field left the host didn't expose.
>>>>
>>>>Peter
>>>
>>>We assume that the host does not know the right square.
>>>
>>>suppose that the host strategy is not to expose a random square.
>>>
>>>62/64 of the games are canceled because the host exposed
>>>the king
>>>
>>>Let look only in 64000 game that the host did not expose g5
>>>
>>>62000 of them are canceled
>>>I win 1000 of them and the friend win 1000 of them.
>>>
>>>The same is for 64000 games when the host did not expose g4.
>>>
>>>For every square that the host does not expose I have the same number
>>>of wins and losses.
>>>
>>>Uri
>>
>>One last trial - to keep the analogy with the original Monty problem and the
>>adding of additional doors.
>>
>>I think it is just like this:
>>
>>1.) You have the first choice -> you take a1
>>2.) The host starts opening doors, he opens 62 of them and none has the king (he
>>is just lucky or he knows, doesn't matter).
>
>It is important.
>
>>3.) Then he adresses me : Which of the 64 fields that don't have Uri on them do
>>you want to choose -> I choose the one not exposed yet
>>4.) Then he adresses you: do you want to keep with your square or change to
>>Peter's?
>>
>>There are only two interesting squares left - one of them has the king. But I
>>think you will agree that yours sucks compaired to mine.
>>
>>Peter
>
>If the king was not exposed by luck then I do not agree.
>
>Last try to explain:
>Let suppose he does not know where is the king.
>
>Let suppose that I am not allowed to change my choice and I win only if I chose
>the king.
>My chances are 1/64 to be right.

Agreed.

>
>1)Do you agree that if he expose the king when he expose 62 squares then it is
>bad luck for me and I lost the game?

No. The game is canceled in this case. We assume the king is not exposed.

>
>2)Do you agree that it means that if he did not expose the king that it is good
>luck for me and the probability that my guess was correct increased?

No. Your odds are still 1/64.

>
>3)Do you agree that it means that my probability is more than 1/64 after he
>exposed no king?

No, when you stick to yóur initial choice.

>
>I say that it is 1/2 after exposing 62 squares.
>
>Uri

Greetings,
Gerrit



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