Software Defined Networks (SDNs) have been a new paradigm to separate the network control plane from the data forwarding plane. Controller placement is one fundamental problem which identifies the number of controller...
详细信息
Recent years have witnessed a tremendous growth using topological summaries, especially the persistence diagrams (encoding the so-called persistent homology) for analyzing complex shapes. Intuitively, persistent homol...
详细信息
The cycle packing number ve(G) of a graph G is the maximum number of pairwise edgedisjointcycles in G. Computing ve(G) is an NP-hard *** present approximation algorithms for computing v e(G) in both undirected and dir...
详细信息
The cycle packing number ve(G) of a graph G is the maximum number of pairwise edgedisjointcycles in G. Computing ve(G) is an NP-hard *** present approximation algorithms for computing v e(G) in both undirected and directed graphs. In the undirected case we analyze a variant of the modified greedy algorithm suggested by Caprara et al. [2003] and showthat it has approximation ratio Θ(√log n), where n = |V(G)|. This improves upon the previous O(log n) upper bound for the approximation ratio of this algorithm. In the directed case we present √n-approximation algorithm. Finally, we give an O(n2/3)- approximation algorithm for the problem of finding a maximum number of edge-disjoint cycles that intersect a specified subset S of *** also study generalizations of these problems. Our approximation ratios are the currently best-known ones and, in addition, provide upper bounds on the integrality gap of standard LP-relaxations of these problems. In addition, we give ower bounds for the integrality gap and approximability of ve(G) in directed graphs. Specifically, we prove a lower bound of Ω( log n log log n) for the integrality gap of edge-disjoint cycle packing. We also show that it is quasi-NP-hard to approximate ve(G) within a factor of O(log1-Ε n) for any constant Ε > 0. This improves upon the previously known APX-hardness result for this problem.
In this paper we consider the following time constrained scheduling problem. Given a set of jobs J with execution times e(j) E (0, 1] and an undirected graph G = (J, E), we consider the problem to find a schedule for ...
详细信息
This paper studies the stochastic variant of the classical k-TSP problem where rewards at the vertices are independent random variables which are instantiated upon the tour’s visit. The objective is to minimize the e...
详细信息
We consider the classical geometric problem of determining a shortest path through a weighted domain. We present approximation algorithms that compute Ε-short paths, i.e., paths whose costs are within a factor of 1 +...
详细信息
ISBN:
(纸本)1581131844
We consider the classical geometric problem of determining a shortest path through a weighted domain. We present approximation algorithms that compute Ε-short paths, i.e., paths whose costs are within a factor of 1 + Ε of the shortest path costs, for an arbitrary constant Ε > O, for the following geometric configurations: SPPS Problem: We are given a polyhedron P consisting of n convex faces and each face has a positive non-zero real valued weight. The shortest path on polyhedral surface problem (SPPS) is to compute a path of least cost that remains on the surface of P between any two vertices, where the cost of the path is defined to be the weighted sum of Euclidean lengths of the sub-paths within each face. Our algorithm runs in O(n/Ε log 1/Ε (1/√Ε + log n)) time for 0
Scheduling problems where the machines can be represented as the edges of a network and each job needs to be processed by a sequence of machines that form a path in this network have been the subject of many research ...
详细信息
In the Movement Repairmen (MR) problem we are given a metric space (V, d) along with a set R of k repairmen r1, r2,...,rk with their start depots s1, s2,...,sk ∈ V and speeds v1, v2,...,vk ≥ 0 respectively and a set...
详细信息
In this paper we present an overview about new approximation results for several optimization problems. During the last years we have worked on the design of approximation algorithms with a smaller approximation ratio...
详细信息
There are two major aspects of Data Privacy -identity disclosure and attribute disclosure. A number of algorithms have been developed to protect identity disclosure. However, many of these algorithms have not been muc...
详细信息
暂无评论