The Croatian Science Foundation grant IP-2018-01-7491

The theory of dynamical systems and especially the study of chaotic systems has been one of the important
breakthroughs in science in the 20th century. The field is still relatively young, but there is no question that it is
becoming more and more important in a variety of disciplines. Scientists have been able to apply the geometric and
qualitative techniques from dynamical systems to a number of important nonlinear problems ranging from physics and
chemistry to ecology and economics. Ergodic theory, topological, hyperbolic, symbolic dynamics, all has been developed as
disciplines in their own right. Development of powerful computers and computer graphics has shown that the dynamics of
low-dimensional systems can be at once beautiful and complicated.

The goal of the project is to study certain classes of these beautiful and complicated low-dimensional chaotic
dynamical systems. More precisely, our objectives are to investigate the following problems:

(1) The Lozi and Lozi-like maps of the plane. There are a lot of open problems related to the dynamics of these families
of maps. One of them, which we plan to study, is the transition between simple and chaotic dynamics, that is, the
transition from zero to positive topological entropy. We also plan to further investigate the chaotic dynamics, especially
the topological properties of the Lozi and Lozi-like attractors, and recently developed symbolic dynamics on these
attractors.

(2) The area-preserving twist diffeomorphisms on a cylinder. There is a number of fundamental ergodic theoretical questions
still unanswered for these classes of maps, in particular related to obtaining sharp bounds on topological and metric
entropy and Lyapunov exponents. We plan to develop further recently developed variational techniques to address these
problems.

(3) Ergodic theory on the Heisenberg group. We plan to derive estimates providing quantitative information on the norm
convergence of double ergodic averages with respect to two flows/maps generating the Heisenberg group. This will be
achieved by investigating properties of left-invariant flows and the corresponding analytical averages on the continuous
Heisenberg group, which is an interesting structure on its own. As byproducts of this investigation we will also deduce
boundedness and convergence of paraproducts with Heisenberg group dilations and characterize general pairs of flows l
eading to bounded paraproducts.

The expected results of the project are to further develop some aspects of the low-dimensional dynamical systems
and to contribute to deeper understanding of the theory.

- Kristijan Kilassa Kvaternik, PhD student
- Vjekoslav Kovač, Associate Professor
- Siniša Slijepčević, Professor
- Sonja Štimac, Professor (PI)

Address: Department of Mathematics, University of Zagreb, Bijenička 30, 10 000 Zagreb, Croatia