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ICC
2007
IEEE
104views Communications» more  ICC 2007»
15 years 4 months ago
Joint Design of Tx-Rx Beamformers in MIMO Downlink Channel
We consider a single-cell multiple-input multiple-output (MIMO) downlink channel where linear transmission and reception strategy is employed. The base station (BS) transmitter is...
Marian Codreanu, Antti Tölli, Markku J. Juntt...
FOCS
2008
IEEE
15 years 4 months ago
Beating the Random Ordering is Hard: Inapproximability of Maximum Acyclic Subgraph
We prove that approximating the Max Acyclic Subgraph problem within a factor better than 1/2 is Unique-Games hard. Specifically, for every constant ε > 0 the following holds:...
Venkatesan Guruswami, Rajsekar Manokaran, Prasad R...
PODS
2007
ACM
159views Database» more  PODS 2007»
15 years 9 months ago
Generalized hypertree decompositions: np-hardness and tractable variants
The generalized hypertree width GHW(H) of a hypergraph H is a measure of its cyclicity. Classes of conjunctive queries or constraint satisfaction problems whose associated hypergr...
Georg Gottlob, Thomas Schwentick, Zoltán Mi...
CP
2010
Springer
14 years 7 months ago
The Lattice Structure of Sets of Surjective Hyper-Operations
Abstract. We study the lattice structure of sets (monoids) of surjective hyper-operations on an n-element domain. Through a Galois connection, these monoids form the algebraic coun...
Barnaby Martin
CVPR
2003
IEEE
15 years 11 months ago
Transforming Camera Geometry to A Virtual Downward-Looking Camera: Robust Ego-Motion Estimation and Ground-Layer Detection
This paper presents a robust method to solve the two coupled problems: ground layer detection and vehicle egomotion estimation, which appear in visual navigation. We virtually rot...
Qifa Ke, Takeo Kanade