A disk-based parallel implementation for direct condensation of large permutation modules

  • Authors:
  • Eric Robinson;Jürgen Müller;Gene Cooperman

  • Affiliations:
  • Northeastern University, Boston, MA;Lehrstuhl D für Mathematik, RWTH Aachen, Aachen, Germany;Northeastern University, Boston, MA

  • Venue:
  • Proceedings of the 2007 international symposium on Symbolic and algebraic computation
  • Year:
  • 2007

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Abstract

Through the use of a new disk-based method for enumerating very large orbits, condensation for orbits with tens of billions of elements can be performed. The algorithm is novel in that it offers efficient access to data using distributed disk-based data structures. This provides fast access to hundreds of gigabytes of data,which allows for computing without worrying about memory limitations. The new algorithm is demonstrated on one of the long-standing open problems in the Modular Atlas Project [11]: the Brauer tree of the principal 17-block the sporadic simple Fischer group Fi23 The tree is completed by computing three orbit counting matrices for the Fi23 orbit of size 11, 739, 046, 176 acting on vectors of dimension 728 over GF (2). The construction of these matrices requires 3-1/2 days on a cluster of 56 computers,and uses 8 GB of disk storage and 800 MB of memory per machine.