On September 15-23, 2024, seminars on the topic "Operators and waves" were held at the Institute of Mathematics of the Polish Academy of Sciences (Warsaw) within the framework of scientific work under the NAWA IMPRES-U project: Spectral and geometric methods for damped wave equations with applications to fiber lasers. The representatives of South Ukrainian National Pedagogical University named after K. D. Ushynsky were invited to the seminars: Pivovarchyk Vyacheslav Mykolayovych, Doctor of Sciences in Physics and Mathematics, the Head of the Department of Higher Mathematics and Statistics, Professor; Boyko Olha Pavlivna, PhD in Physics and Mathematics, Associate Professor of the Department of Applied Mathematics and Informatics, and Alesya Supranovich, the student of the 1st year of master's level studies in specialty Secondary Education (Physics and Astronomy) of the Institute of Natural and Mathematical Sciences, Informatics and Management. Professor V. M. Pyvovarchyk gave a speech on the topic " Restoration of the form of the graph according to the spectrum of the Sturm-Liouville equation."