Results 1 - 10 of 556

Wireless Network Information Flow: A Deterministic Approach

by A. Salman Avestimehr, et al. , 2009
"... In contrast to wireline networks, not much is known about the flow of information over wireless networks. The main barrier is the complexity of the signal interaction in wireless channels in addition to the noise in the channel. A widely accepted model is the the additive Gaussian channel model, and ..."
Abstract - Cited by 296 (42 self) - Add to MetaCart
, but not the values of the channel gains or the signal-to-noise ratios. We show that existing strategies cannot achieve such a constant-gap approximation for arbitrary networks and propose a new quantizemap-and-forward scheme that does. We also give several extensions of the approximation framework including

1 Interference Alignment: From Degrees-of-Freedom to Constant-Gap Capacity Approximations

by Urs Niesen, Mohammad A. Maddah-ali
"... ar ..."
Abstract - Add to MetaCart
Abstract not found

Wireless Network Information Flow: A Deterministic Approach

by unknown authors , 2009
"... In contrast to wireline networks, not much is known about the flow of information over wireless networks. The main barrier is the complexity of the signal interaction in wireless channels in addition to the noise in the channel. A widely accepted model is the the additive Gaussian channel model, and ..."
Abstract - Add to MetaCart
, but not the values of the channel gains or the signal-to-noise ratios. We show that existing strategies cannot achieve such a constant-gap approximation for arbitrary networks and propose a new quantizemap-and-forward scheme that does. We also give several extensions of the approximation framework including

On the Limits of Non-Approximability of Lattice Problems

by Oded Goldreich, Shafi Goldwasser , 1998
"... We show simple constant-round interactive proof systems for problems capturing the approximability, to within a factor of p n, of optimization problems in integer lattices; specifically, the closest vector problem (CVP), and the shortest vector problem (SVP). These interactive proofs are for th ..."
Abstract - Cited by 99 (2 self) - Add to MetaCart
We show simple constant-round interactive proof systems for problems capturing the approximability, to within a factor of p n, of optimization problems in integer lattices; specifically, the closest vector problem (CVP), and the shortest vector problem (SVP). These interactive proofs

Approximating edit distance efficiently

by Ziv Bar-yossef, T. S. Jayram, Robert Krauthgamer, Ravi Kumar - In Proc. FOCS 2004 , 2004
"... Edit distance has been extensively studied for the past several years. Nevertheless, no linear-time algorithm is known to compute the edit distance between two strings, or even to approximate it to within a modest factor. Furthermore, for various natural algorithmic problems such as low-distortion e ..."
Abstract - Cited by 36 (5 self) - Add to MetaCart
-distortion embeddings into normed spaces, approximate nearest-neighbor schemes, and sketching algorithms, known results for the edit distance are rather weak. We develop algorithms that solve gap versions of the edit distance problem: given two strings of length n with the promise that their edit distance is either

Constant Factor Lasserre Integrality Gaps for Graph Partitioning Problems

by Venkatesan Guruswami, Ali Kemal, Sinop Yuan Zhou
"... Partitioning the vertices of a graph into two roughly equal parts while minimizing the number of edges crossing the cut is a fundamental problem (called Balanced Separator) that arises in many settings. For this problem, and variants such as the Uniform Sparsest Cut problem where the goal is to mini ..."
Abstract - Cited by 3 (2 self) - Add to MetaCart
is to minimize the fraction of pairs on opposite sides of the cut that are connected by an edge, there are large gaps between the known approximation algorithms and non-approximability results. While no constant factor approximation algorithms are known, even APX-hardness is not known either. In this work we

Approximation algorithms for allocation problems: Improving the Factor

by Uriel Feige - of 1 − 1/e. Proc. of IEEE FOCS , 2006
"... Combinatorial allocation problems require allocating items to players in a way that maximizes the total utility. Two such problems received attention recently, and were addressed using the same linear programming (LP) relaxation. In the Maximum Submodular Welfare (SMW) problem, utility functions of ..."
Abstract - Cited by 59 (9 self) - Add to MetaCart
of players are submodular, and for this case Dobzinski and Schapira [SODA 2006] showed an approximation ratio of 1 − 1/e. In the Generalized Assignment Problem (GAP) utility functions are linear but players also have capacity constraints. GAP admits a (1 − 1/e)approximation as well, as shown by Fleischer

Constant Integrality Gap LP Formulations of Unsplittable Flow on a Path

by Aris Anagnostopoulos, Fabrizio Grandoni, Stefano Leonardi, Andreas Wiese , 2013
"... The Unsplittable Flow Problem on a Path (UFPP) isacore problem in many important settings such as network flows, bandwidth allocation, resource constraint scheduling, and interval packing. We are given a path with capacities on the edges and a set of tasks, each task having a demand, a profit, a sou ..."
Abstract - Cited by 4 (4 self) - Add to MetaCart
whose LP-relaxation has an integrality gap that is provably constant. For the unweighted case, we show that adding a few constraints to the standard LP of the problem is sufficient to make the integrality gap drop from Ω(n) to O(1). This positively answers an open question in [Chekuri et al., APPROX

Approximate Bounds for Limited Backhaul Uplink Multicell Processing with Single-User Compression

by Yuhan Zhou, Wei Yu
"... Abstract—This paper studies single-user compression for the uplink multi-cell processing (MCP) model where multiple basestations are connected to a central processor via noiseless backhaul links with a sum capacity constraint. The proposed scheme is based on the virtual multiple-access channel (V-MA ..."
Abstract - Cited by 1 (0 self) - Add to MetaCart
dominant channel criterion and show the constant-gap result for the case when the covariance matrix of the received signals across the base-stations is κ-strictly diagonally dominant for some constant κ> 1. Second, we show that the constant-gap result holds for a special class of Wyner channel models

Streaming and sublinear approximation of entropy and information distances

by Sudipto Guha, Andrew Mcgregor, Suresh Venkatasubramanian - In ACM-SIAM Symposium on Discrete Algorithms , 2006
"... In most algorithmic applications which compare two distributions, information theoretic distances are more natural than standard ℓp norms. In this paper we design streaming and sublinear time property testing algorithms for entropy and various information theoretic distances. Batu et al posed the pr ..."
Abstract - Cited by 67 (13 self) - Add to MetaCart
and yields an asymptotic constant factor approximation scheme. An integral part of the algorithm is an interesting use of an F0 (the number of distinct elements in a set) estimation algorithm; we also provide other results along the space/time/approximation tradeoff curve. Our results have interesting
Results 1 - 10 of 556