Person: Vidav, Ivan
Ivan Vidav was a Slovenian mathematician who worked in differential equations, functional analysis and algebra.
Mathematical Profile (Excerpt):
 In 1937 Vidav began to study mathematics at the University of Ljubljana.
 They often discussed mathematics of all kinds and on one occasion, after his lecture in 1940, Plemelj mentioned to Vidav an open problem concerning homogeneous linear differential equations.
 Then, during the summer holidays of 1940, the 22 year old Vidav solved the problem and passed the solution to professor Plemelj at their first meeting at the beginning of the autumn semester.
 Although this is the first paper of Ivan Vidav, it contains no beginner's deficiency; on the contrary, it has the flavour of a mature mathematician's work.
 This first original scientific work of Vidav, in which he considered the socalled Fuchsian differential equation with five singular points, became the basis of his dissertation entitled The theorems of Klein in the theory of linear differential equations.
 It is worth mentioning that Vidav was awarded his diploma and the Ph.D. degree (with Plemelj as advisor) in the same year, 1941, just when the war was spreading to SouthEast Europe.
 The final result is called the 'VidavPalmer theorem'.
 Some other notions and results are named after Vidav: a definition of Hermitian elements, a lemma about their numerical range, an involution, and an algebra.
 In the following years Vidav published further papers on functional analysis, some in German, some in French, and later some in English.
 In the midsixties, physicists attracted Vidav to consider various problems in neutron transport theory.
 Vidav became, as a longtime chair, the master architect of the Mathematics Department at the University of Ljubljana after 1960.
 Professor Vidav was a leading scientific and moral authority in Slovenian mathematics after World War Two until his retirement.
Born 17 January 1918, Opcine, near Trieste, Italy. Died 6 October 2015, Ljubljana, Slovenia.
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Origin Italy
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References
Adapted from other CC BYSA 4.0 Sources:
 Oâ€™Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive