Re: probability space: how to understand the following?

In article
<18478878.1159832384809.JavaMail.jakarta@xxxxxxxxxxxxx
forum.org>,
Yuwu Xiong <xiongyw@xxxxxxxxxxx> wrote:

what i do not understand is the following two
sentences:

"Alpha consists of subsets A of Omega such that if
(a,b) E A then (a,b) E A.
there are 2^21 such subsets out of the total 2^36; "

Either you miscopied it or there is a typo in the
original. I think it
should read

"Alpha consists of subsets A of Omega such that if
(a,b) E A then (b,a) E A.
there are 2^21 such subsets out of the total 2^36; "


Mike Guy

thanks for the reply, mike.

i think u are correct.

after a short thinking, "if (a,b) E A then (b,a) E A" will
lead to 2^21: 6 + 30/2 = 21. where 6 is the number of (a,b) with
a=b, and 30/2 is the number of set {(a,b), (b,a)} with a!=b.

btw, this is a typo in the original copy of the english translation.

thanks again,
/bruin
.