Wednesday, 11 February 2026 130 years since the birth of a forgotten Slovenian mathematician
On February 11, 2026, a round table was held at UP FAMNIT in Koper to celebrate the release of the freely accessible electronic edition of the book The Life Path of Mathematics of Ivo Lah by Janez Mulec and the release of the commemorative postage stamp Ivo Lah – 130 years of birth, which was issued by Pošta Slovenije at the end of January.
The participants of the round table shed light on the life and work of Ivo Lah (1896–1979), a Slovenian mathematician, actuary, statistician and demographer, who with his work significantly marked the development of mathematical and actuarial sciences in the wider Central European area.
The work and, above all, the life of Ivo Lah was described in a book published at the end of 2023 by Janez Mulec the Elder. Prof. Dr. Tomaž Pisanski advocated that the University of Primorska also publish it in freely accessible electronic form.
The event was led by Dr. Simona Kustec, editor-in-chief of the University of Primorska Publishing House. The round table was attended by Dr. Janez Komelj, Dr. Tomaž Pisanski and Dr. Janez Mulec, who from different professional perspectives shed light on the significance of Lah's work and its influence on today's research in mathematics, actuarial science and statistics.
About Ivo Lah
Ivo Lah was born in 1896 in Štrukljeva vas and studied in Vienna and Zagreb. Early in his career, he established himself as one of the leading actuaries in the Balkans. Between 1937 and 1940, he published the first scientific journal with actuarial and mathematical content in Ljubljana, Glasnik Udruženja aktuara Kraljevine Jugoslavije, in which contributions were also published in the Slovene language, which made a significant contribution to the development of professional terminology.
In 1942 he published the first mortality tables, and after World War II the trilingual monograph Računske osnovnice životnog osiguranja (1947), which served as an expert basis for negotiations on war reparations; as a member of the Yugoslav state delegation, he participated in the negotiations in Rome. In 1954 he introduced numbers that were soon named after him – Lah numbers. These connect increasing and decreasing powers and, together with Stirling numbers, form an important structure in discrete mathematics. Although they originated in the context of actuarial research, they quickly found a place in modern mathematics and are still the subject of research today. Despite the scientific weight of his contributions, Ivo Lah was overlooked for many decades. It was only in 2002 that it became generally known that the author of Lah numbers was Slovenian. The mystery was solved by mathematicians Tomaž Pisanski and Marko Petkovšek. His professional and personal journey was also marked by post-war stigma, as he disagreed with the social order of the former Yugoslavia in many ways and was unjustly punished by losing his right to vote after the end of World War II.
