Raul Miller wrote:
> I think that randomness might be something of a distraction
> from the main point

OK: here's my argument.

Let p and q be random nonzero integers.

Define events

E   : denominator of reduced fraction p/q is even.

E(n): q is divisible by 2^n ; q is divisible by 2^n-1 but not 2^n.

Then the E(n) constitute a partition of E.

Since p(E(n))=1/2^(2*n),

p(E)=1/4+1/16+1/64+....=1/3.

The same argument gives the even more surprising result that the
probability of the denominator being divisible by a prime p is
1/((p^2)-1.

The problem of this argument is that it depends on p and q: the E(n)'s
become empty after a while.  Whether this is is important depends on
how randomness is defined.

Best wishes,

John



----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm

Reply via email to