A Note on: `Algorithms for Connected Set Cover Problem and   Fault-Tolerant Connected Set Cover Problem'
  A flaw in the greedy approximation algorithm proposed by Zhang et al. for minimum connected set cover problem is corrected, and a stronger result on the approximation ratio of the modified greedy algorithm is established. The results are now consistent with the existing results on connected dominating set problem which is a special case of the minimum connected set cover problem. 
Wei Ren, Qing Zhao
cs.DS