Heng Cao, Haifeng Xi, et al.
WSC 2003
We show that the standard linear programming relaxation for the tree augmentation problem in undirected graphs has an integrality ratio that approaches frac(3, 2). This refutes a conjecture of Cheriyan, Jordán, and Ravi [J. Cheriyan, T. Jordán, R. Ravi, On 2-coverings and 2-packings of laminar families, in: Proceedings, European Symposium on Algorithms, 1999, pp. 510-520. A longer version is on the web: http://www.math.uwaterloo.ca/jcheriyan/publications.html] that the integrality ratio is frac(4, 3). Crown Copyright © 2008.
Heng Cao, Haifeng Xi, et al.
WSC 2003
James Lee Hafner
Journal of Number Theory
W.C. Tang, H. Rosen, et al.
SPIE Optics, Electro-Optics, and Laser Applications in Science and Engineering 1991
Charles A Micchelli
Journal of Approximation Theory