Romanas Yanushkevichius (in Lithuanian – Januškevičius, born July 10, 1953 in Vilnius) is a Lithuanian mathematician who worked in probability theory and characterization of probability distributions and its stability, professor of Lithuanian University of Educational Sciences, head of the Department of Mathematics, Informatics and Physics since 2001 until 2017, educator, participated actively in the preparation of teachers of mathematics and informatics in Lithuania.
Yanushkevichius was born in Vilnius on July 10, 1953. He graduated from one of Vilnius high school in 1971 and entered Vilnius University, from which he graduated in 1976.
In 1976-1978 Yanushkevichius trained in Steklov Institute of Mathematics in Moscow, where under the guidance of Professor Vladimir Zolotarev wrote and in 1978 he defended his thesis “Investigation of stability in some problems of characterization of distributions“ and received the Candidate of Sciences degree. The main result of this thesis was the work of the author , which considered the stability for decompositions of probability distributions into components.
Work and research interests
Characterization theorems in probability theory and mathematical statistics are such theorems that establish a connection between the type of the distribution of random variables or random vectors and certain general properties of functions in them. For example, the assumption that two linear (or non-linear) statistics are identically distributed (or independent, or have a constancy regression and so on) can be used to characterize various populations. Verification of conditions of this or that characterization theorem in practice is possible only with some error, i.e., only to a certain degree of accuracy. Such a situation is observed, for instance, in the cases where a sample of finite size is considered. That is why there arises the following natural question. Suppose that the conditions of the characterization theorem are fulfilled not exactly but only approximately. May we assert that the conclusion of the theorem is also fulfilled approximately? Questions of this kind give rise to a following problem: determine the degree of realizability of the conclusions of mathematical statements in the case of approximate validity of conditions.
In solving these problems, a special place is given to the convolution equation. Decisions of non-homogeneous convolution equations on the half and applications for building stability estimations in characterizations of probability distributions devoted one of the major works of the author . His investigation of stability of characterizations of probability distributions R. Yanushkevichius has completed in the book  in 2014.
Since 1997 until 2017 Yanushkevichius is the professor of Vilnius Pedagogical University. The main emphasis of his pedagogical activity – the training of teachers of mathematics and informatics.
Yanushkevichius pays great attention to the field of spiritual enlightenment. What is man? What is the real purpose of short human life? What will happen after death? Is it all going to end after death? Or, on the contrary, everything just starts? Are there absolute laws of human existence? Where lies the boundary between right and wrong? Moreover, why is there so much injustice?
For this problems is devoted the book of R. Yanushkevichius and O. Yanushkevichiene «Basics of ethics“, which has stood 8 editions (1st edition – Vilnius, Open Society Fund-Lithuania, 8th edition – Pro-Press Publisher, Moscow, 2010). The book was translated into the Ukrainian language , . Patriarch Alexy II during his visit to Vilnius on 25-27 July 1997 personally handed for Yanushkevichius Order of the Moscow Saint Duke Daniel of III degree  for the diligent work for the blessing of Orthodoxy in Lithuania in the affair of revival of spirituality. In April 2018 he was awarded the Jubilee Medal of Patriarch Kirill.
- ↑ Yanushkevichius. On estimates of the stability measure for decompositions of probability distributions into components. Theory of probability and its applications, 1978, vol. 23, N 3, p. 507-520.
- ↑ Yanushkevichius. Stability for characterizations of distributions. Vilnius, Mokslas, 1991.
- ↑ Yanushkevichius. Convolution equations in stability problems on characterizations of probability laws. Theory of probability and its applications, 1988, vol. 33, N 4, p. 668-681.
- ↑ Yanushkevichius. Stability characterizations of some probability distributions. Saarbrücken, LAP LAMBERT Academic Publishing, 2014.
- ↑Роман Янушкавічос, Ольга Янушкявічене. Основи благочестя. Бесіди з етики для старшокласників. Посібник для 9-11 кл., Астро, 570 стр., Киев, 2007.
- ↑Основи благочестя. Бесіди з етики для старшокласників. Издательство Астро, 570 стр., Киев, 2005. (Подробное описание книги).
- ↑Patriarchal decree on awarding the Order of the Moscow Saint Duke Daniel of III degree, 1997.
- Between Mathematics and Theology. List of R. Januškevičius publications, available in eLABa (Lithuanian Academic e-library) and in Research Gate.