Professor Valentin Vladimirovich Petrov passed away on 31 May, 2025. He was born on 10 February, 1931, into the family of a physician in Kholomky in the Pskov region of Russia. In 1952 he finished his studies at the Faculty of Mathematics and Mechanics of the University of Leningrad (St. Petersburg). He started his PhD studies supervised by Yuri Linnik and defended his thesis three years later. Linnik also inspired him to conduct research on limit theorems for sums of independent random variables, and Petrov devoted his scientific life to this topic. It was also the title of his Habilitation thesis (Doctor of Science) defended at the Academy of Sciences of the Soviet Union in Moscow in 1961. Shortly after, in 1963, he became Professor at the University of Leningrad. From 1961–95 he chaired the Department of Probability Theory and Mathematical Statistics at the University of Leningrad.

Petrov was one of the world experts for limit theorems in probability theory and probability inequalities. His mathematical work went into the depth of existing results by Lyapunov, Cramér, Esseen, Gnedenko, and Linnik. He refined their findings in elegant ways and turned them into seminal statements. Petrov’s name is closely related to fundamental results in the theory of large deviations, improving upon results by Cramér and Linnik. He was a master in developing the necessary tools for deriving these results, including numerous generalizations of Borel–Cantelli lemmas and the inequalities by Lyapunov, Kolmogorov, Bernstein, and Lévy. These tools were successfully applied in the context of a.s. limit theory: he found necessary and sufficient conditions for generalized strong laws of large numbers and laws of the iterated logarithm.

Professor Petrov was an outstanding teacher at the University of Leningrad/St. Petersburg. In his lectures he presented the beauty and elegance of probability theory. He also lectured at numerous universities, including in USA, Mexico, Argentina, Uruguay, Switzerland, Germany, Brazil, Denmark. He loved teaching limit theory for sums of independent random variables and devoted his first monograph, Sums of Independent Random Variables, to this topic. First published in Russian in 1972 (Nauka, Moscow), the 1975 English translation became a global success (Springer, Berlin, Heidelberg). It served generations of probabilists and statisticians as an encyclopedic source of probability inequalities, rates of convergence, moment estimates, local and central limit theorems, a.s. limit theory, and so on. The monograph Limit Theorems of Probability Theory (Oxford University Press, 1995) was another publishing success. Petrov used this text for teaching graduate courses in many countries.

Valentin Petrov was a person with a subtle humor. For example, when his third monograph (1987, Nauka) was printed on beautiful white paper he explained this with the fact that the paper was actually reserved for Leonid Brezhnev’s last book; the Soviet leader had died in 1985, and nobody would read his books afterwards.

Petrov liked to talk about inspiring meetings with William Feller, Jerzy Neyman, Lucien Le Cam, C.R. Rao, Harald Cramér, Peter G. Hall, Allan Gut, and many others. He loved the arts and literature, and wrote poems himself.

For his achievements as a teacher, department chair and his world-wide reputation as a scientist and author, Petrov received various national and international awards and honors. He had 21 PhD students of whom eight chose a scientific career.

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Written by Sergey Ananjevskii, Allan Gut, Ildar Ibragimov, Mikhail Lifshits, Thomas Mikosch, and Valery Nevzorov