Don reble wrote:
 
<<
[Guy Haworth wrote:
> In the 'knockout' first round involving 128 players and 64 matches, what
> is the probability that none of 19 specific players are matched against
> each other?
 
            126*124*122*120*...*92
Could it be ---------------------- ~= .20822833 ?
            127*126*125*124*...110
>>
 
I wrote what amounts to
 
<<
109*108*107*...92*91
--------------------,
127*125*123*...93*91
>>
 
which is ~= .20822833 also,
 
so I presume Don's answer is another way to calculate
the same probability.  But I don't see why yet.  Can
someone please explain his method to me?
 
--Dan