Before revision:  First, we show that this algorithm can achieve an approximation factor of 0.405, which significantly improves the known factor of 0.357 given by Wolsey or (1-1/e)/2\approx 0.316 given by Khuller et al.
After revision:  First, we show that this algorithm can achieve an approximation factor of 0.405, which significantly improves the known factors of 0.357 given by Wolsey or (1-1/e)/2\approx 0.316 given by Khuller et al.