S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Industrial Engineering (산업공학과) Journal Papers (저널논문_산업공학과)
Approximability of the k-Server Disconnection Problem
- Hong, Sung-Pil; Choi, Byung-Cheon
- Issue Date
- Networks 50(2007), 273-282
- server–network disconnection; inapproximability; approximation algorithm; fixed-parameter cases
- The definitive version is available at www3.interscience.wiley.com.
- Consider a network of k servers and their users. Each server provides a unique service that has a certain utility for each user. Now comes an attacker who wishes to destroy a set of network edges to maximize his net gain, namely the total disconnected utilities of the users minus the total edge-destruction cost. This k -server disconnection problem is NP-hard and, furthermore, cannot be approximated within a polynomially computable factor of the optimumwhen k is part of the input. Even for any fixed k ≥ 2, there is a constant > 0 such that approximation of the problem within a factor 1/(1 + ) of the optimum is NP-hard. However, a 12 + 1 2k+1−2 -approximation can be created in the time of O(2k ) applications of a min-cut algorithm. The main idea is to approximate the optimum with special solutions computable in polynomial time due to supermodularity. Therefore, when the the network has, as is usual in most cases, only a few servers, a 0.5-approximation can be carried out in polynomial time.
- Files in This Item: There are no files associated with this item.