[extropy-chat] Re: monty hall paradox again: reds and green gorfs

[Alejandro Dubrovsky]

On Sat, 2004-05-22 at 19:48 -0700, Spike wrote:

> > Eliezer Yudkowsky
> >
> > >  ...The probability that
> > > the other envelope is larger must go to 1/3, it doesn't
> > > matter how it gets there."
> > 
> > Your mathematician friend is flat wrong, and needs to study Bayesian 
> > probability theory. --  Eliezer S. Yudkowsky 
> 
> OK cool, I was hoping someone would say that.  So where
> is the error?  Are you saying that Bayesian reasoning
> predicts that there *is* a profit in swapping?  Even
> if you have no idea how much a zorg is?  How do you
> set up the Bayesian priors?  How do you set up a
> sim to prove it?
> 

Like Brett said, the results change depending on how the problem is
stated.  If you run a simulation and you get an agent to stick and one
to switch on two envelopes one containing twice the amount of the other,
then they both end up with the same amount.  But if you set it up so
that the sticker gets 10 and the switcher gets 5 or 20 with equal
probability then switcher wins.  Of course, this equal probability is
set a posteriori to getting the 10, and it clashes with it having a 1/3
- 2/3 probability that comes up in the first simulation.  How this makes
any sense is beyond me, and will ruin me for another week at least.

(btw, spike, could you tell me if you got any of the two emails that i
sent to you directly?  your isp doesn't seem to like mine)

alejandro