150th anniversary of Josip Plemelj's birth

Josip Plemelj was born on 11 December 1873 in Bled. He studied mathematics, physics and astronomy in Vienna, earning a PhD in mathematics in 1898. From 1908 onward, he was full professor of mathematics at the University of Chernivtsi in Ukraine, where he also served as dean of the Faculty of Arts from 1912 to 1913. Even though he could have pursued a brilliant international academic career, he returned home and helped establish the first Slovenian university. In 1919, he was elected the first rector of the University of Ljubljana andwas full professor of mathematics from 1919 to 1957, first at the Faculty of Arts and later at the Faculty of Natural Sciences. He was a full member of the Slovenian Academy of Sciences and Arts from its inception in 1938, and a corresponding member of the Yugoslav (Zagreb), Serbian and Bavarian academies of sciences.

Plemelj's main research interests were differential equations in the complex domain, the Riemann–Hilbert problem, Fredholm's theory of integral equations and its application to potential theory, and similar topics. His most original and important contribution to science was the elementary solution he provided for the Riemann–Hilbert problem, which mathematicians had tried to solve for some fifty years, with no success in finding a sufficiently general solution. Plemelj published his solution in 1908, presenting his famous formula that he applied to jump matrices in Cauchy-type integrals on a curve, also known in the literature as the Plemelj jump formula. Even today this remains the best-known and most often cited achievement by a Slovenian mathematician. The solution is based on three formulas that now carry his name (the Plemelj formulae, and sometimes also the Sokhotsky-Plemelj formulae).

In 1949, Plemelj became the first honorary member of the Slovenian Society of Mathematicians, Physicists and Astronomers, to which he left his house in Bled. In 1954, he received the Prešeren Award and in 1963 he was awarded an honorary doctorate from the University of Ljubljana. Plemelj died on 22 May 1967 in Ljubljana.

The Republic of Slovenia is issuing a commemorative coin to mark the 150th anniversary of Josip Plemelj's birth. The design on the coin features part of an equation, with numbers and symbols that rotate in circles and illustrate the rotation of the planets, movement in space and at the same time the merging of individual insoluble elements into a whole. In this way, the coin illustrates Josip Plemelj's two areas of work and research: mathematics and astronomy.


Event proposed by: Jože Nemec, PAZU, SAZU, Municipality of Bled, University of Ljubljana, Slovenian Society of Mathematicians, Physicists and Astronomers, Marjan Godnjov

Artwork designed by: Jasna Čuk Kolavčič, Šempeter pri Gorici

Minting: Istituto Poligrafico e Zecca dello Stato, Italy

Commemorative coin Commemorative coin - proof
Nominal value: EUR 2
Issued: 990,250 coins
Nominal value: EUR 2
Issued: 3,000 coins
Issue date: 19. 12. 2023 Scheduled issue date Q1 2024

The list of Banka Slovenije's numismatic products and their availability as well as their price can be found at the following web page.