Explore the intricacies of Nijenhuis geometry in this advanced mathematics lecture delivered as part of the Thematic Programme on "Geometry beyond Riemann: Curvature and Rigidity" at the Erwin Schrödinger International Institute for Mathematics and Physics. Delve into complex mathematical concepts and theories as the speaker presents the fourth installment in a series on Nijenhuis geometry. Gain insights into cutting-edge research and developments in this specialized field of mathematics over the course of 51 minutes.