**Jan Popken** was a Dutch mathematician specialising in number theory.

- Popken was taught by Johan Antony Barrau (1873-1953) who had been advised by Diederik Korteweg for his doctorate.
- Another of Popken's teachers, who arrived in Groningen in 1923, was the number theorist Johannes Gaultherus van der Corput (1890-1975).
- Popken graduated with a candidate's degree (the candidate's degree in the Netherlands is a first degree of the standard of a B.Sc.) on 15 February 1927.
- Popken continued to study at Groningen, undertaking research, and obtained a second degree cum laude on 2 July 1930.
- Let us try to explain the problem on which Popken was undertaking research.
- The problem of finding the transcendental measure of e was posed by Émile Borel in 1899 and, in 1928, soon after he had completed his first degree, Popken read Borel's paper and decided to try to improve the bound for the transcendental measure of e.
- After graduating in July 1930, Popken spent two semesters at the University of Göttingen with the number theorist Edmund Landau.
- The result of the expertise that Popken gained from Edmund Landau was seen in his joint paper with Jurjen Koksma, Zur Transzendenz von eπ Ⓣ(On the Transcendence of e π) which was published by Crelle's Journal in 1932.
- After the study trip to Göttingen, Popken returned, for financial reasons back to his birthplace Smilde.
- In Popken's dissertation there are fifteen major propositions with almost twice as many, most elaborate, minor propositions, which, all artfully and ingeniously combined, yield exactly the intended results.
- In 1937 Popken habilitated at the University of Groningen with the thesis Over het rekenkundig karakter van getalen Ⓣ(On the arithmetic character of numbers).
- Popken left Groningen and moved to the University of Leiden where he was appointed as a docent in 1940.
- Popken was still able to work as a school teacher but he had no university position until 1945 when the war ended.
- After the war Popken was appointed as a scientific assistant at the University of Groningen, a position he held from 1945 to 1947.
- The war had caused a gap in Popken's publication record which had been an average of around two papers a year up to 1940.
- On 19 August 1950 Popken arrived in New York having sailed on the Volendam from Rotterdam, Netherlands.
- H D Kloosterman was chair of this committee with Haantjes as its secretary and Popken as one of the three other members.
- Popken held the position as professor at the University of Utrecht for eight years before moving to Amsterdam when he was appointed as Professor of analysis, algebra and number theory at the university there on 19 January 1955.
- The Amsterdam inaugural lecture of Prof dr Popken, also addresses the non-mathematicians in his audience in a richly documented argument.
- Popken spent the summer of 1959 at the University of California in Berkeley.
- While at Berkeley, from 18 June to 20 July 1959, Popken delivered the course 'Elementary mathematics for advanced students'.
- Popken was on his way the spend time at the University of California in Berkeley and gave their address in the United States as 1597 Hawthorne Terrace, Berkeley.
- While in the United States, Popken participated in the 1962 conference 'Studies in mathematical analysis and related topics' held at Stanford University.
- On 12 April 1965 Popken changed from the position of Professor of Analysis, algebra and number theory to being Professor of Pure Mathematics, still at the University of Amsterdam.
- In the later stages of his career, Popken became increasingly interested in the history of mathematics.

Born 14 December 1905, Hijkersmilde, near Smilde, Netherlands. Died 6 August 1970, Amsterdam, Netherlands.

View full biography at MacTutor

Origin Netherlands

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