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STOC
2006
ACM
113views Algorithms» more  STOC 2006»
14 years 6 days ago
Logarithmic hardness of the directed congestion minimization problem
We show that for any constant ε > 0, there is no Ω(log1−ε M)approximation algorithm for the directed congestion minimization problem on networks of size M unless NP ⊆ Z...
Matthew Andrews, Lisa Zhang
ECCC
2006
88views more  ECCC 2006»
13 years 6 months ago
Hardness of Directed Routing with Congestion
Given a graph G and a collection of source-sink pairs in G, what is the least integer c such that each source can be connected by a path to its sink, with at most c paths going th...
Julia Chuzhoy, Sanjeev Khanna
STOC
2005
ACM
135views Algorithms» more  STOC 2005»
14 years 6 months ago
Hardness of the undirected congestion minimization problem
We show that there is no log log M log log log M -approximation for the undirected congestion minimization problem unless NP ZPTIME(npolylog n ), where M is the size of the grap...
Matthew Andrews, Lisa Zhang
STOC
2007
ACM
134views Algorithms» more  STOC 2007»
14 years 6 months ago
Hardness of routing with congestion in directed graphs
Given as input a directed graph on N vertices and a set of source-destination pairs, we study the problem of routing the maximum possible number of source-destination pairs on pat...
Julia Chuzhoy, Venkatesan Guruswami, Sanjeev Khann...
MFCS
2007
Springer
14 years 12 days ago
Hardness Results for Tournament Isomorphism and Automorphism
A tournament is a graph in which each pair of distinct vertices is connected by exactly one directed edge. Tournaments are an important graph class, for which isomorphism testing ...
Fabian Wagner