综合论述了理论计算机科学领域中两个密切相关的NP-困难问题:分组Steiner问题和覆盖Steiner问题的不同解决途径.并就其若干特殊情形设计了近似比更好的近似算法。
We review different avenues to solve two closely-related NP-hard problems in theoretical computer science,the group Steiner problem and the covering Steiner problem,and design improved approximation algorithm for some special cases of them.