**Jan Mikusiński** was a Polish mathematician known for his pioneering work in mathematical analysis.

- Jan Geniusz took part in the January Uprising of 1863, which began when Poles objected to being conscripted into the Russian Army.
- Jan Geniusz fled to Austria but later returned to Lithuania having changed his name to Mikusiński to avoid reprisals.
- Jan Mikusiński's maternal grandparents were Leopold Beldowski, an Austrian nobleman, and Emilia Skomorowska.
- Jan's school education was in Poznań.
- He entered the Ignacy Jan Paderewski Humanistic Gymnasium in 1923 and studied there for five years.
- Although Mikusiński excelled in mathematics, it was engineering that had always been his main interest.
- The University of Poznań was closed down by the occupying German forces in October 1939 and many of the faculty were arrested - Mikusiński fled to Kraków.
- The participants of Ważewski's seminar, in 1943, were the first persons to come in contact with a new theory which is now very well known in the world of mathematics as the Mikusiński operational calculus.
- stand for Jan G.-Mikusiński (G, being the first letter of Geniusz, the author's patronymic, which he later abandoned).
- The paper 'Hypernumbers' represents the first version of the Mikusiński operational calculus (improved afterwards by the use of the Titchmarsh theorem) and contains already the main ideas of this theory.
- In January 1945 Soviet forces liberated Kraków from the German occupation.
- Even before that Mikusiński had been undertaking research advised by Tadeusz Ważewski, but once the city was liberated, he was able to obtain an official position at the Jagiellonian University of Kraków.
- By the time Mikusiński was awarded his Ph.D., the Polish University of Poznań had reopened and he was able to return there and take up a position as assistant professor in the department headed by Władysław Orlicz.
- Mikusiński worked at the State Mathematical Institute from its foundation.
- The Mikusiński operational calculus was successfully used in ordinary differential equations, integral equations, partial differential equations and in the theory of special functions.
- It is worth mentioning that the Mikusiński scheme was extended by several mathematicians to develop operational calculi for differential operators with variable coefficients ...
- Mikusiński's career took an unfortunate turn shortly after he became a full professor.
- The State Mathematical Institute had become the Mathematical Institute of the Polish Academy of Sciences after the Academy was founded in 1952 and Mikusiński retained his position at the Institute.
- In 1960 Mikusiński moved to Katowice.
- After a year, the lectures turned to a regular seminar, first held at the Higher Pedagogical School, then at Mikusiński's home.
- The informal scientific contacts of Professor Mikusiński with Silesian mathematicians became formal only in 1966 when the Mathematical Laboratory (now the Branch of the Mathematical Institute of the Polish Academy of Sciences) was established.
- The existence of the seminar led to the establishment of the Katowice Branch of the Institute of Mathematics of the Polish Academy of Sciences which Mikusiński headed from its founding in 1966 until 1985.
- Mikusiński had, before the founding of the Katowice Branch of the Institute of Mathematics, been made head of the Department of Mathematical Analysis in the Mathematical Institute of the Polish Academy of Sciences.
- We should mention a number of Mikusiński's books in addition to The Calculus of Operators (1953) which we discussed above.
- Mikusiński received numerous honours, prizes and awards.
- Jan Mikusiński died on 27 July 1987 and was buried on the cemetery in Katowice.
- When Studia Mathematica published Mikusiński's 1944 paper Hypernumbers in 1983 it was to celebrate both the 40th anniversary of the original publication and Mikusiński's 70th birthday.

Born 3 April 1913, Stanislawów, Austrian-Hungarian Empire (now Ivano-Frankivsk, Ukraine). Died 27 July 1987, Katowice, Poland.

View full biography at MacTutor

Origin Ukraine

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive