Approximation algorithms for NP-hard problems
The quest for security in mobile ad hoc networks
MobiHoc '01 Proceedings of the 2nd ACM international symposium on Mobile ad hoc networking & computing
Self-Organized Public-Key Management for Mobile Ad Hoc Networks
IEEE Transactions on Mobile Computing
Certificate Dispersal in Ad-Hoc Networks
ICDCS '04 Proceedings of the 24th International Conference on Distributed Computing Systems (ICDCS'04)
An Optimal Certificate Dispersal Algorithm for Mobile Ad Hoc Networks*
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Complexity of approximating bounded variants of optimization problems
Theoretical Computer Science - Foundations of computation theory (FCT 2003)
Algorithmic construction of sets for k-restrictions
ACM Transactions on Algorithms (TALG)
An Approximation Algorithm for Minimum Certificate Dispersal Problems
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Stabilizing certificate dispersal
SSS'05 Proceedings of the 7th international conference on Self-Stabilizing Systems
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Given a graph G = (V ,E ) and a set R *** V ×V of requests, we consider to assign a set of edges to each node in G so that for every request (u , v ) in R the union of the edge sets assigned to u and v contains a path from u to v . The Minimum Certificate Dispersal Problem (MCD) is defined as one to find an assignment that minimizes the sum of the cardinality of the edge set assigned to each node. In this paper, we give an advanced investigation about the difficulty of MCD by focusing on the relationship between its (in)approximability and request structures. We first show that MCD with general R has ***(logn ) lower and upper bounds on approximation ratio under the assumption P *** NP , where n is the number of nodes in G . We then assume R forms a clique structure, called Subset-Full , which is a natural setting in the context of the application. Interestingly, under this natural setting, MCD becomes to be 2-approximable, though it has still no polynomial time approximation algorithm whose factor better than 677/676 unless P = NP . Finally, we show that this approximation ratio can be improved to 3/2 for undirected variant of MCD with Subset-Full.