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

Author: Uri Blass

Date: 14:26:13 09/27/02

Go up one level in this thread


On September 27, 2002 at 17:16:33, Gerrit Reubold wrote:

>On September 27, 2002 at 17:03:35, Uri Blass wrote:
>
>>On September 27, 2002 at 16:25:54, Gerrit Reubold wrote:
>>
>>>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.
>>
>>I was talking about a new game and not about the old game.
>>
>>The rules in the new game game is that I win if the king is in a1 and I lose if
>>the king is in another square.
>>
>>I will try to explain more clearly(I will not talk about winning the game but
>>about your probability to be right in guessing)
>>
>>1)P(a1 is the real place of the king)=1/64 in the beginning of the game.
>
>Agreed.
>
>>
>>2)p(a1 is the real place of the king) is reduced to 0 if the king is exposed in
>>another square.
>
>Agreed, but that doesn't matter, because in the game which I discuss the king is
>_not_ exposed.

It is only in the game that the other side knows the place of the king.
In the game that I discussed the king can be exposed.
The game is canceled but the probability to be at a1 is 1/64 before knowing if
the game will be canceled so we cannot ignore it.

Uri



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