# On three types of dynamics, and the notion of attractor

## TL;DR

This paper introduces a theoretical framework explaining the phenomenon of attractor-repeller merger, classifies attractors into three types, and proves that reversible systems with elliptic orbits exhibit maximal complexity.

## Contribution

It identifies three types of attractors, including a new 'reversible core' type, and proves generic properties of reversible systems with elliptic orbits.

## Key findings

- Reversible cores represent a new type of chaos.
- Generic reversible systems with elliptic orbits are maximally complex.
- The framework explains attractor-repeller mergers in dynamical systems.

## Abstract

We propose a theoretical framework for an explanation of the numerically discovered phenomenon of the attractor-repeller merger. We identify regimes which are observed in dynamical systems with attractors as defined in a work by Ruelle and show that these attractors can be of three different types. The first two types correspond to th ewell-known types of chaotic behavior - conservative and dissipative, while the attractors of the third type, the reversible cores, provide a new type of chaos, the so-called mixed dynamics, characterized by the inseparability of dissipative and conservative regimes. We prove that every elliptic orbit of a generic non-conservative time-reversible system is a reversible core. We also prove that a generic reversible system with an elliptic orbit is universal, i.e., it displays dynamics of maximum possible richness and complexity.