The second homotopy group of the sphere: π₂(S²) in classical and digital topology

A very gentle introduction to the second higher homotopy group of the 2-sphere, plus some digital topology. The paper is: "A Second Homotopy Group for Digital Images" by Gregory Lupton, Oleg Musin, Nicholas A. Scoville, P. Christopher Staecker, Jonathan Treviño-Marroquín, at arxiv here: https://arxiv.org/abs/2310.08706 Talk given at the Fairfield University math department research seminar, Nov 17, 2023.