Explore the third class of the Topology series taught by Oscar Reula from the National University of Córdoba, Argentina, as part of the ICTP-SAIFR Minicourse on Partial Differential Equations: Analytical and Numerical Tools. Delve into advanced topological concepts and their applications in the study of partial differential equations during this 54-minute lecture. This class continues the progression of topological foundations established in previous sessions, providing essential mathematical tools for analyzing PDEs. The minicourse runs from May 5 to June 30, 2025, offering comprehensive training in both analytical and numerical approaches to differential equations.