Next Meeting

Topics:

Permutation Group Algorithms in Parallel Jason Hill University of Colorado Boulder In his 1991 paper on permutation group algorithms based on partitions, Jeffrey Leon commented that the algorithms would be suitable for parallel computations. Yet, twenty years later, no parallel implementation had been attempted. We will discuss a parallel implementation of partition backtrack for permutation group centralizer computations and examine performance on various machines, from personal computers to supercomputers. This talk will span several disciplines (from permutation group algorithms, to programming, to computer architectures) and members of the audience are not expected to be experts in any of those areas.

Completing pseudo-arcs to pseudo-ovals Tim Penttila Colorado State University A pseudo-arc is a set of (n-1)-spaces in projective (3n-1)-space, such that any 3 of them span the whole space. Over a finite field of order q, if such a set has size qn+1, it is called a pseudo-oval (and this is the maximum size if q is odd). How large must a pseudo-arc be in order to be able to be completed to a pseudo-oval? Cameo roles for Laguerre planes, generalized quadrangles and Desargues arise in the course of the talk. (Joint work with Geertrui van de Voorde)