Before revision:  We can further boost the approximation ratio to (1 - 1 / e - \epsilon ) with the help of continuous greedy technique, which gives a tight randomized approximation algorithm for this case .
After revision:  We can further boost the approximation ratio to (1 - 1 / e-\epsilon randomized algorithm for the general case, thus achieving the same result as Fairstein et al. (ESA20) .