Memory-based and disk-based algorithms for very high degree permutation groups

  • Authors:

  • Gene Cooperman;Eric Robinson

  • Affiliations:

  • Northeastern University, Boston, MA;Northeastern University, Boston, MA

  • Venue:
  • ISSAC '03 Proceedings of the 2003 international symposium on Symbolic and algebraic computation
  • Year:
  • 2003

Quantified Score

Hi-index 0.00

Visualization

Abstract

Group membership is a fundamental algorithm, upon which most other algorithms of computational group theory depend. Until now, group membership for permutation groups has been limited to ten million points or less. We extend the applicability of group membership algorithms to permutation groups acting on more than 100,000,000 points. As an example, we experimentally construct a group membership data structure for Thompson's group, acting on 143,127,000 points, in 36 minutes. More significantly, we require approximately 10 GB of RAM for the computation --- even though a single permutation of Thompson's group already requires half a gigabyte of storage.In addition, we propose a disk-based group membership algorithm with the promise of extending group membership to well over one billion (1,000,000,000) points. Such a disk-based algorithm has formerly been impossible, due in part to the lack of a practical disk-based algorithm for multiplying and taking inverses of such large permutations. Random access to disk is prohibitively expensive. We demonstrate the first practical disk-based implementation of the basic permutation operations. We also propose a disk-based architecture for group membership data structures.