In this second part, we try to understand why chaos occurs. We outline an argument that the existence of a 3-periodic solutions implies that the system in question is chaotic.
The argument is adapted from the paper mentioned in the video:
Li, Tien-Yien, and James A. Yorke. "Period three implies chaos." The theory of chaotic attractors (2004): 77-84. link.springer.com/chapter/10.1007/978-0-387-21830-4_6
More on the Sharkovsky ordering can be found here:
www.scholarpedia.org/article/Sharkovsky_ordering
Two good books on nonlinear and chaotic dynamics are
"Chaos" by James Gleick - a popular science book covering the history of chaos theory as a mathematical discipline
"Nonlinear dynamics and Chaos"...