A comment on scheduling on uniform machines under chain-type precedence constraints

In a recent paper, Chekuri and Bender (Proceedings of IPCO’98, pp. 383–393) derive (among other results) a polynomial-time 6-approximation algorithm for makespan minimization on uniform parallel machines subject to chain-type precedence constraints. In this short note, we combine some straightforward observations and thereby derive an extremely simple 2-approximation algorithm for this problem