Before revision:  We can take this advantage even more , precisely we can achieve a CR of 2+R{3} if the number of requests in each stage is at most Rk, 1  R  2, where we do not have to know the value of R in advance.
After revision:  We can take this advantage even more , precisely we can achieve a CR of 2+R{3} if the number of requests in each stage is at most Rk, 1  R \leq R \leq 2, where we do not have to know the value of R in advance.