A note on hierarchical scheduling on two uniform machines

This paper studies online hierarchical scheduling on two uniform machines with the objective to minimize makespan. Machines are provided with different capability, i.e., the one with speed s can schedule all jobs, while the other one with speed 1 can only process partial jobs. Optimal algorithms for any 0<s<∞ are given in the paper. For 0<s<1, it has a competitive ratio of ${\displaystyle min\{1+s,1+\frac{1+s}{1+s+s^2}\}}$ . For s>1, the competitive ratio is ${\displaystyle min\{\frac{1+s}{s},1+\frac{2s}{1+s+s^2}\}}$ .