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Near-Optimal Expanding Generating Sets for Solvable Permutation Groups

2012/01/16 by V. Arvind, Partha Mukhopadhyay, Arvind, V. +5
Computer Science · #Computational Complexity (cs.CC) #Discrete Mathematics (cs.DM) #FOS: Computer and information sciences #cs.CC #cs.DM

paper · pdf · doi:10.48550/arxiv.1201.3181

15 pages

arxiv created 2012/01/16 · arxiv updated 2012/01/17

Abstract

Let G =<S> be a solvable permutation group of the symmetric group Sn given as input by the generating set S. We give a deterministic polynomial-time algorithm that computes an expanding generating set of size O(n2) for G. More precisely, the algorithm computes a subset T⊂ G of size O(n2)(1/λ)O(1) such that the undirected Cayley graph Cay(G,T) is a λ-spectral expander (the O notation suppresses log O(1)n factors). As a byproduct of our proof, we get a new explicit construction of ε-bias spaces of size O(n\poly(log d))((1)/(ε))O(1) for the groups \Zdn. The earlier known size bound was O((d+n/ε2))11/2 given by \citeAMN98.

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