On the Complexity of the Asymmetric VPN Problem
نویسندگان
چکیده
We give the first constant factor approximation algorithm for the asymmetric Virtual Private Network (Vpn) problem with arbitrary concave costs. We even show the stronger result, that there is always a tree solution of cost at most 2·OPT and that a tree solution of (expected) cost at most 49.84 ·OPT can be determined in polynomial time. For the case of linear cost we obtain a (2+ε S )-approximation algorithm for any fixed ε > 0, where S and R (R ≥ S) denote the outgoing and ingoing demand, respectively. Furthermore, we answer an outstanding open question about the complexity status of the so called balanced Vpn problem by proving its NPhardness.
منابع مشابه
The Effect of Asymmetric Water Entry on the Hydrodynamic Impact
The effect of the asymmetric water entry over a submerged part of a ship on the hydrodynamic impact is investigated numerically. A wedge body is considered to study and the problem is assumed to be two-dimensional. The Results of symmetric and asymmetric impacts are compared together. The effect is found significant in the numerical simulation. The maximum hydrodynamic pressure at a heel angle ...
متن کاملPerformance Analysis of Rejection Ratio in Cost Optimized Virtual Private Networks Provisioning Algorithm (COVPA) Using Waxman and Barabasi Model in Cyber Space
Problem statement: Virtual private networks have provided customers with a secure and low-cost communication environment. Approach: The COVPA, the provisioning algorithm for a Virtual Private Network service, which built and managed VPNs on demand. Results: The COVPA allowed each VPN to have guaranteed resources and customized control and supported a highly dynamic VPN service where creation an...
متن کاملAlgorithms for Provisioning Virtual Private Networks in the Hose Model
Virtual Private Networks (VPNs) provide customers with predictable and secure network connections over a shared network. The recently proposed hose model for VPNs allows for greater flexibility since it permits traffic to and from a hose endpoint to be arbitrarily distributed to other endpoints. In this paper, we develop novel algorithms for provisioning VPNs in the hose model. We connect VPN e...
متن کاملVirtual Private Network Design: A Proof of the Tree Routing Conjecture on Ring Networks
A basic question in Virtual Private Network (VPN) design is if the symmetric version of the problem always has an optimal solution which is a tree network. An affirmative answer would imply that the symmetric VPN problem is solvable in polynomial time. We give an affirmative answer in case the communication network within which to create the VPN is a circuit. This seems to be an important step ...
متن کاملModelling and Experimental Testing of Asymmetric Information Problems in Lease and Hire Contracts (Based on Contract Theory)
This article aims to study lease and hiring contract in the Iranian-Islamic setting and analyze the asymmetric information problem in these contracts. For doing this, we study the characteristics of lease and hiring contracts in Iran (real world experimental characteristics that recognized in other studies), using library method, then we mathematically model different aspects of asymmetric info...
متن کامل