Geometry and Topology in Physical Models


International PhD Programme in Mathematics, Mathematical Physics and Computer Science


15. Homological methods in rigorous numerics of dynamical systems

Polish supervisor: Marian Mrozek
Cooperating partners: Konstantin Mischaikow (Rutgers University)
Warwick Tucker (Uppsala University)


The goal of this project is to develop new efficient algorithms for computing homological invariants of dynamical systems. Such topological invariants as the Conley index, fixed point index, connection matrices proved to be very helpful in rigorous numerical analysis of the asymptotic behaviour of dynamical systems. In particular, the first proof of the existence of chaos in the Lorenz equations presented in 1995 by Mischaikow and Mrozek was based on such methods. Since then numerous other problems in dynamics were settled by such or similar methods.

The direct computation of homological invariants is particularly important in the automated analysis of the asymptotic behaviour of a dynamical system under various values of a multidimensional parameter. Of course the extend of the applicability of such a method crucially depends on the efficiency of the applied algorithms. This causes a lasting demand for fast algorithms computing homological invariants of dynamical systems. The particularly challenging situation is the case of dynamical systems given by the Poincare map of a differential equation with stron expansion of error bounds. Recent work by Mrozek and Srzednicki shows that at least in some situations the very expensive rigorous integration of the differential equation for a long time may be avoided by studying the topology of the exit set of an isolating segment.

The student is expected to work on
  • the theory - finding a method to express the Conley index and/or the fixed point index of the Poincare map in terms of some computable information on the topology of the exit set of a respective isolating segment
  • the algorithms for extracting the necessary information on topology
which should result in an efficient method for computing some homological invariants of dynamical systems defined by the Poincare map.