September 29, 2025 marked the 70th birthday of Oleg Ivanovich Klesov, Doctor of Physical and Mathematical Sciences, Professor, and Head of the Department of Mathematical Analysis and Probability Theory.
O.I. Klesov has been working at the Kyiv Polytechnic Institute since 1990: first as an associate professor, and since 2002, after defending his doctoral dissertation, as a professor. Since 2012, Oleg Ivanovich has been the head of the Department of Mathematical Analysis and Probability Theory of the Faculty of Physics and Mathematics.
Oleg Ivanovich Klesov is a well-known specialist in Ukraine and worldwide in the field of probability theory and random processes. O.I. Klesov's scientific output includes more than 300 scientific and scientific-methodological works, including five monographs. Oleg Ivanovich is an academician of the Academy of Sciences of Higher Education of Ukraine. He is the head of joint scientific projects with universities in Germany, France, and Switzerland, the curator of cooperation agreements between Igor Sikorsky KPI and universities in France, Germany, Sweden, and Norway, as well as the head of initiative and state budget topics.
O.I. Klesov successfully combines intensive scientific work with organizational and pedagogical activities. Oleg Ivanovich initiated the opening of the educational program “Insurance and Financial Mathematics” at the department, the purpose of which is to train highly qualified specialists whose knowledge, competence, and skills meet modern global requirements. He is the guarantor of the educational program “Mathematics” of the third (educational and scientific) level of higher education. Oleg Ivanovich is one of the leading teachers of the department, teaching normative and elective educational components within the educational program “Insurance and Financial Mathematics” of the first (bachelor's) and second (master's) levels of higher education and the educational program “Mathematics” of the third (educational and scientific) level of higher education. Oleg Klesov has developed new educational components, in particular “Development of Classical Ideas in Modern Mathematics” and “Random Wandering in Financial Mathematics Problems.” His lectures are an example of high pedagogical and methodological skill, impressing with their depth of thought and vividness of form, richness of new ideas, clarity, and accessibility of presentation. His creative approach to presenting material, his ability to interest students in the subject, and his sense of humor have earned him well-deserved respect among students and colleagues.
Professor O.I. Klesov actively works with young scientists and is a scientific supervisor of master's and doctoral dissertations. It is rare to find scientists who devote so much time to their graduate and postgraduate students. He patiently teaches, guides, and defends them in difficult situations.
A small digression. A word to Oleg Ivanovich's students.
"In my third year, I realized that I had to choose the Department of Mathematics and Theory of Information for further study, because Oleg Ivanovich's classes were the only ones I could never skip. Moreover, it turned out that probability theory and random process theory can be interesting, and the problems can be modern and related to real life. In general, it was Oleg Ivanovich, my scientific advisor, who inspired me to get into programming, because his incredibly complex problems could take years to solve, and modeling the experiment often suggested the way to the solution," says Natalia Kruglova.
“Oleg Ivanovich knows how to lead the audience to a paradox, when intuition fails and a mathematical trick is born. Once you realize this, mathematics no longer lets you go; it becomes the source of the only truth,” says Alexander Kolesnik.
Under the guidance of Professor O.I. Klesov and Professor O.V. Ivanov, a scientific seminar “Statistical Problems for Random Processes and Fields” has been operating at the department since 2012.
O.I. Klesov is the chair of ad hoc specialized academic councils for awarding the degree of Doctor of Philosophy. O.I. Klesov is the editor-in-chief of the journal “Mathematics in Modern Technical University” and a member of the editorial board of the journals “Theory of Stochastics Process” and “Scientific Notes of NaUKMA.”
He is the organizer of the first stage of the All-Ukrainian Student Olympiad in the academic discipline “Mathematics,” active assistant in conducting the mathematical holiday “Pi Day,” student “Mathematical Battles,” wise advisor and participant in the organization by the Department of Mathematical Analysis and Probability Theory of a number of international and All-Ukrainian scientific conferences on mathematics, in particular, “Mathematics in a Modern Technical University,” “M. Kravchuk International Conference,” “All-Ukrainian Scientific Conference of Young Mathematicians” – this is all about Oleg Ivanovich Klesov.
Since 2024, he has also been a member of the NAQA Sectoral Expert Council in the field of knowledge 11 “Mathematics and Statistics.”
In 2009, O.I. Klesov received a second-degree diploma as the winner of the competition for the best diploma project for supervising diploma design, in 2011 he became the winner of the competition “Teacher-Researcher of NTUU ”KPI", and in 2014, he won the NTUU “KPI” award for the best textbook, manual, or monograph. Oleg Ivanovich has been repeatedly awarded with Honorary Diplomas from Igor Sikorsky KPI. Oleg Klesov is a distinguished educator of Ukraine.
Through his conscientious work over many years, friendly relations with colleagues in the team, and support in these difficult times, Oleg Ivanovich has earned deep respect.
Please accept sincere congratulations and best wishes for good health for many years to come, boundless energy, great human happiness, prosperity, and a long and happy life from the staff of the Department of Mathematical Analysis and Probability Theory.
Your students join in:
"Oleg Ivanovich is not only an outstanding mathematician and a true leader of the department, but also a modern, European-oriented personality. Thanks to his openness and support for the most daring ideas, we have been able to implement many projects that went far beyond the usual.
We remember the unique Ukrainian-Austrian scientific project, which was among only 17 selected throughout Ukraine, the incredible Ukrainian-Norwegian educational partnership (2016-2023), as well as Mathematics Week at KPI, which grew into an event not only on a university scale, but also on a broader scale. All this was made possible thanks to Oleg Ivanovich's energy, creativity, and inspiration.
We sincerely wish you good health, inexhaustible energy, and new original ideas that will continue to unite people and open new horizons in science and education.
With deep respect and gratitude," writes Olena Tymoshenko.