Speaker: Christopher Jefferson (St Andrews)
Title: Dynamically Created Orderings for Finding Orbit Representatives in Permutation Groups
Abstract:
Finding if two algebraic structures are in the same orbit of a group G is a computationally difficult problem. One practical algorithm is to calculate the minimal image of the structure under the group -- two structures are in the same orbit if and only if they have the same minimal image. This raises an obvious question -- What ordering should the minimal image be taken under? We will show how the ordering used can greatly effect the practical performance of the algorithm, and how a good ordering can be created for a given group and algebraic structure.