Explore a captivating conference talk from the International Conference on Dynamical Systems, featuring Stefano Marmi from SNS-Pisa. Delve into the intricacies of Brjuno functions, Hölder continuity, and modular forms in this 46-minute presentation. Part of a broader event celebrating Marcelo Viana's 60th birthday, this talk showcases cutting-edge research in dynamical systems. Organized by the renowned Dynamics group at IMPA, the conference brings together leading researchers to discuss active topics and present new developments in the field. Gain insights into advanced mathematical concepts and their applications in this engaging lecture, hosted by the Instituto de Matemática Pura e Aplicada in Rio de Janeiro.