From: smortaz@handel.Eng.Sun.COM (Shahrokh Mortazavi)
Newsgroups: soc.culture.iranian
Subject: seyed's topogh du jour
Date: 12 Oct 92 18:38:07 GMT
Organization: Sun Microsystems, Mountain View, CA  USA
NNTP-Posting-Host: handel


well seyed jaan, from your refusal to answer my pending questions, 
i can only assume that you have *finally* seen the light and have chosen
to be silent vs admitting to - god forbid - being, ahem, wrong.

its truuuuuly amusing that the *only* person who got stomped by 
the puzzle, cries foul and says that it was stated in a deceiving 
manner (me and a couple of sci readers had a good laugh about this 
over dinner last night!):

>That's because the problem, as stated by shahrokh, is vague and subject to
>different interpretations.
 ~~~~~~~~~~~~~~~~~~~~~~~~~

yes, especially your creative ones!

your original analysis (prior to resorting to 'oh, i interpreted it
differently' - apology tactic #4) was, ahem, wrong, as we all know:

>Wrong! "Given that #2 is empty", #1 and #3 are again equiprobable, and this
>is consistent with intuition, because your first choice (of #1) doesn't affect
>anything. 

your move to rephrase the puzzle, such that your, ahem, wrong answer
would be 'right', was pure entertainment.  all that trouble - creating
a whole new puzzle - just to cover up your topogh (am i using the
proper word, seyed?).    

even after i tried explaining it to you, you still didnt get the point and
ahem, wrongly tried to point out that *i* was mistaken:

sm> if you stay with door #1, youre chances of being right is 
sm> still only what?  1/100?  very good!  you get a cookie and and a pat

seyed> Fascinating!!!

well, since your intuition has failed you, and your logic needs a
tune up, let me explain again in *still* simpler terms, and hope that
youll get it.  actually, i think now you know that i was right
all along, and thats why youre not answering the questions.

first, the problem as stated originally isnt vague at all:

   3 doors, behind one is a prize.  you pick a door.
   host opens another door and shows you its empty (_obviously_
   implying knowledge about where the prize is, daaaaa).
   what is the probability of your first choice being right
   (of course, assuming this game is played repeatedly)?

from your comments:

> my previous solution is absolutely correct, and it doesn't
> make any difference [to switch].

>"Given that #2 is empty", #1 and #3 are again equiprobable, 
>and this is consistent with intuition,

its clear that you think that the remaining two doors have
an equal probability of holding the prize.  ahem, wrong.
no matter how you (humanly) interpreted it.  


		explanation attempt #2 
   (dont know how many more are needed before he gets it):

assume the following:

	door#1		door#2		door#3
	 		Prize		

you pick a door, randomly, say #1.  this divides the universe
of possibilities into two parts:
		
		 |
	door#1	 |	door#2		door#3
	         |	Prize	

          1/3 chance	        2/3 chance 

now, as the puzzle originally stated, i open a door and
show you there is no prize behind it:

		 |
	door#1	 |	door#2		
	         |	Prize	

          1/3		 2/3 

your 'i am absolutely correct' and 'it doesnt make any difference'
comments indicate you think that the chances for door#1 have
been 'increased' to 50%.  ahem, wrong again.  

you see, once you take away door#3, no matter what, 2/3's of the
time the prize is in the right half of the universe.  the chances
of the left side remain 1/3 and dont magically increase by 
eliminating door#3. 

perhaps if i 'plug in' the values youd belive your eyes
emaam seyed:

pick = you pick a door
open = i open empty door
   
   door 1	door 2	        door 3	     	switch  stay
   ------------ --------------  ----------   	------  ----
   Prize  	   -		-
   
   pick		open		-		lose  	win	
   -		pick		open		win	lose	
   -		open		pick		win	lose	
   						

   door 1	door 2	        door 3	     	switch  stay
   ------------ --------------  ----------   	------  ----
   -		Prize		-
   
   pick		-		open		win   	lose
   -		pick		open		lose	win 
   open		-		pick		win	lose	


   door 1	door 2	        door 3	     	switch  stay
   ------------ --------------  ----------   	------  ----
   -		-		Prize
   
   pick		open		-		win   	lose
   open		pick		-		win	lose 
   -		open		pick		lose    win
   
   
   				totals wins	6       3

so as you can see, it pays to switch.  infact, no matter what is
done with the other doors (as long as the prize door or at least
one empty door isnt opened [obviously, or we'd be 100% sure 
where the prize is, daaaaaaa]) sticking with your original choice 
gives you a 1/n chance of winning.

well, so much for your intuition & logic.  

and of course, there is a non-zero possibility that i could be all
wrong!  and if someone convinces me (including you) that i am, i
shall apologize, thank them and be in their debt forever.  too
bad your version of islam hasnt taught you this virtue.
frankly, we all know the problem doesnt lie with islam at all,
but rather with your overgrown ego, which qualifies for having
its very own nine digit zipcode.
Newsgroups: soc.culture.iranian