**Octav Onicescu** was a Romanian mathematician with research interests that included many areas such as probability, Riemannian manifolds, absolute differential calculus, functional analysis, algebra, and the topological theory of functions. He is considered as the founder of the Romanian school of probability.

- Octav's primary education was at the Boys' Primary School in Botoşani and then he entered the "August Treboniu Laurian" High School, one of the best high schools in the country, which had been founded in 1858.
- In 1911 Onicescu took the baccalaureate examinations, and then enrolled in the Faculty of Sciences of the University of Bucharest; he also attended courses in the Faculty of Philosophy.
- Onicescu attended lectures in the Faculty of Philosophy by Constantin Radulescu-Motru (1868-1957) and Petre Paul Negulescu (1870-1951).
- At the University of Bucharest, Onicescu won the admiration of his teachers, especially Gheorghe Țițeica, the leading Romanian mathematician at that time.
- Onicescu and Țițeica became friends and had a long mathematical collaboration.
- In 1913 Onicescu graduated in Mathematics and Philosophy, completing his studies a year earlier than his fellow students.
- This Military High School had only been founded in 1912, two years before Onicescu began teaching there, by Nicolae Filipescu.
- Octav and Luiza Onicescu had two sons, Dan and Mircea.
- Mircea Onicescu (1925-2011) became a gynaecologist.
- Onicescu volunteered for military action and joined the Romanian army as an active fighter on the front.
- Onicescu ended his military service in 1918.
- We see how topical this was if we note that Albert Einstein had only published the general theory in late 1915, three years before Onicescu began to undertake research.
- In his thesis Onicescu took the 3-dimensional ideas of these papers and generalised them into the 4-dimensional analogues relevant to general relativity.
- We should note here that while Onicescu was in Rome, he attended lectures on probability by Francesco Paolo Cantelli.
- These lectures, based on Guido Castelnuovo's book Calcolo della probabilità Ⓣ(Calculus of probability) (1919), created a strong impression and later in his career, Onicescu would do impressive work on probability and statistics.
- After the award of his doctorate, Onicescu spent the year 1920-21 in Paris.
- Élie Cartan's lectures on integral invariants made a strong impression on Onicescu and gave him an interest in mechanics.
- Onicescu organised a seminar in which all these Romanians took part.
- After his year in Paris, Onicescu returned to Romania where he continued as a teacher at the Military High School at the Dealu Monastery but was invited to lecture on general relativity at several institutions.
- In 1922 Onicescu was appointed as a lecturer in the Faculty of Sciences of the University of Bucharest.
- It is perhaps surprising that he headed departments concerning very different areas of mathematics but we should emphasise that Onicescu's mathematical interests were indeed very broad.
- In 1924 Onicescu gave a course on Probability, Statistics and Applications, the first university level course on this topic to be given in Romania.
- There are two distinct phases to Onicescu's work on probability.
- He undertook research for a doctorate advised by Onicescu and, in 1934, he submitted his thesis On the general properties of dependent statistical variables (Romanian) to the University of Bucharest and was awarded a doctorate in mathematics on 28 April of that year.
- We noted above that there was a second phase in Onicescu's work on probability.
- Another of Onicescu's contributions was his work on mechanics.
- Onicescu's activities were so broad that it is impossible to give details of most of his contributions to the development of mathematics and statistics in Romania.
- A Probability Section of the Institute of Mathematical Sciences was created in 1949 with Onicescu as its head.
- Onicescu was hard working up to the end.
- Among the many honours given to Onicescu let us mention that he was elected a full member of the Romanian Academy in 1965, was elected as member of the Academy of Science in Torino in 1976 and became an honorary member of the International Statistical Institute in 1982.
- The "Octav Onicescu" museum was founded in Botoşani in October 1995; it is the only museum in Romania for a mathematician.

Born 20 August 1892, Botoșani, North Moldavia (now Romania). Died 19 August 1983, Bucharest, Romania.

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Origin Romania

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