Author: Uri Blass
Date: 07:18:19 09/27/02
Go up one level in this thread
On September 27, 2002 at 10:04:42, Gerrit Reubold wrote: >On September 27, 2002 at 09:45:47, Uri Blass wrote: > >>On September 27, 2002 at 08:50:27, Gerrit Reubold wrote: >>> >>>I don't care what that probability was _before_ he opened the door. The door >>>with the goat is _now_ open. >> >>Suppose for the discussion that the candidate also guess door 1 >>and the host always open door 3 in case that door 1 has a goat. > >Do you mean "... in case that door 3 has a goat" ? You are right. I should assume he always choose door 3. I did a mistake here and I thought for a minute that if door 1 has a goat the game is over but the rest of my claims hold. > >(I assume that the host _must_ open a door, he is not allowed to keep both doors >closed.) > >I discuss this situation: >- The candidate chooses door 1 >- The host chooses (say) door 3, and is lucky, there is a goat in door 3 > >So there _is_ a game! > >Now the candidate should switch and double its winning chances. > >Do you agree? No > >If you don't agree: Consider the game with 1.000.000 doors, the candidate >chooses door 1. The host opens 999.998 doors, without knowing where the car is. >By incredible luck all those doors have goats behind them. There is now door 1 >and door 432.102 closed. So again there is a game! Do you agree that the >candidate should switch? No in 100000 cases you are going to have 999998 cases when there is no game 1 case when there is a game when it is a good idea to switch and 1 case when there is a game when it is a bad idea to switch It means that the probability to be right in switching is the same as the probability to be wrong in switching. > > >BTW, this seems all obvious to me, maybe we are discussing different situations? > >Greetings, >Gerrit I admit that I did a mistake in the start of my post. The words "in case that door 1 has a goat" that were wrong. Uri
This page took 0.03 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.