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CC 513 2023
Coin set
Proof
Coin set proof
Slovenia · 150th birthday of Josip Plemelj
Mintage750
Issue price€90.00
Issue date19 Dec 2023
PackagingCoin set
Edge letteringSLOVENIJA •
Market price€129.90
Issue occasion
The coin commemorates the 150th birthday of the mathematician and astronomer Josip Plemelj. The design shows parts of an equation he was the first to solve; numbers and symbols on orbital paths illustrate planetary movements as well as the combining of individual unsolvable elements into a whole. The inscriptions “JOSIP PLEMELJ 1873” and “SLOVENIJA” are incorporated.
The design
The coin design depicts parts of the equation that Josip Plemelj was the first person in the world to solve. Numbers and symbols are arranged along orbital paths that illustrate the rotation of the planets, movement through space and, at the same time, the combination of individual insoluble elements into a whole. The coin design thus combines Plemelj’s two fields of work and research: mathematics and astronomy. The inscription “JOSIP PLEMELJ 1873”, the name of the issuing country “SLOVENIJA” and the year of issue “2023” are incorporated into the design.
The outer ring of the coin depicts the twelve stars of the European flag.
The outer ring of the coin depicts the twelve stars of the European flag.
Background on the topic
Josip Plemelj came from the area around Bled and studied mathematics, physics and astronomy at the University of Vienna (Universität Wien). His scientific career began there while it was still within the Habsburg monarchy. Later, he taught at the University of Czernowitz (Universität Czernowitz), which at that time also belonged to Austria-Hungary. After the First World War, he returned to the newly established Kingdom of Serbs, Croats and Slovenes and worked in Ljubljana.
Plemelj’s mathematical work primarily concerned function theory, differential equations and singular integral equations. The Sokhotski-Plemelj formulas are closely associated with his name. They describe how the boundary values of certain complex integrals on the two sides of a curve relate to each other. Such methods make it possible to address boundary-value problems in complex analysis.
Plemelj’s work on the so-called Riemann-Hilbert problem was also based on this. Put simply, the problem is to find an analytic function whose values exhibit a prescribed jump when crossing a given contour. The problem goes back to questions raised by Bernhard Riemann and was included by David Hilbert in his list of mathematical problems. At the beginning of the 20th century, Plemelj developed a method of solution that became fundamental to the further theory of integral equations and boundary-value problems. His work in astronomy was particularly connected with mathematical methods for describing the motion of celestial bodies.
Plemelj also played an institutional role in Slovenian higher education. The University of Ljubljana (Universität Ljubljana) was founded in 1919, after the dissolution of Austria-Hungary had created the political conditions for a university with Slovenian as its language of instruction. Plemelj was among its professors in the early period and became its first rector. In this way, he contributed to the development of independent mathematical and scientific education in Slovenia.
The choice of Plemelj for a Slovenian commemorative coin is therefore explained not only by his research. Plemelj also represents the development of modern mathematics and the emergence of university-level scholarship in the Slovenian language. His round-number birthday provided the specific occasion to commemorate both aspects together.
Plemelj’s mathematical work primarily concerned function theory, differential equations and singular integral equations. The Sokhotski-Plemelj formulas are closely associated with his name. They describe how the boundary values of certain complex integrals on the two sides of a curve relate to each other. Such methods make it possible to address boundary-value problems in complex analysis.
Plemelj’s work on the so-called Riemann-Hilbert problem was also based on this. Put simply, the problem is to find an analytic function whose values exhibit a prescribed jump when crossing a given contour. The problem goes back to questions raised by Bernhard Riemann and was included by David Hilbert in his list of mathematical problems. At the beginning of the 20th century, Plemelj developed a method of solution that became fundamental to the further theory of integral equations and boundary-value problems. His work in astronomy was particularly connected with mathematical methods for describing the motion of celestial bodies.
Plemelj also played an institutional role in Slovenian higher education. The University of Ljubljana (Universität Ljubljana) was founded in 1919, after the dissolution of Austria-Hungary had created the political conditions for a university with Slovenian as its language of instruction. Plemelj was among its professors in the early period and became its first rector. In this way, he contributed to the development of independent mathematical and scientific education in Slovenia.
The choice of Plemelj for a Slovenian commemorative coin is therefore explained not only by his research. Plemelj also represents the development of modern mathematics and the emergence of university-level scholarship in the Slovenian language. His round-number birthday provided the specific occasion to commemorate both aspects together.
Interesting Facts
This coin set contains all eight circulating coins from 1 cent to 2 euros, this 2-euro commemorative coin and a 3-euro collector coin (face value: 8,88 €).