On page 56 (Python ver.), it’s wrote, after stating we have p, q, initially, “We select the next packet, r, with probability 2/3. Suppose it is not selected.” My question is that why do we have 2/3 as a prob. that r belongs to new subset when we choose only one element out of three candidates, [p, q, r], even considering the replacing procedure afterwards?
i hope this helps