**Moritz Abraham Stern** was a German mathematician who worked in number theory.

- Gauss in particular had a big influence on Stern's mathematical taste as he introduced him to number theory, which became one of his main areas of interest.
- Already in 1829 Stern received a doctorate for his thesis Observationum in fractiones continuas specimen Ⓣ(Some observations on continued fractions) on the theory of continued fractions.
- In 1848 Stern was finally appointed to an extraordinary professorship.
- Stern was not the first Jew to become an extraordinary professor, but even making a Jew a Privatdozent would have caused outrage at many other universities.
- Stern however stayed in Germany and was determined to become a professor.
- Interestingly, Stern was by no means a devout Jew, but belonged to Liberal or Reform Judaism.
- One reason for this appointment was the numerous petitions and recommendations that Stern's friends and colleagues, including the university's rector, had been sending to the government of the Kingdom of Hanover for the past 20 years.
- During his 55 years at the University of Göttingen, Stern lectured on a wide variety of topics, including algebraic analysis, analytic geometry, differential and integral calculus, variational calculus, mechanics, popular astronomy and, of course, number theory.
- In any case, Riemann received a profound knowledge of the state of the art of analysis as taught in Germany at that time from Stern's lectures on calculus.
- Stern's chair at Göttingen was filled by Felix Klein.
- Upon arrival in Zürich, Moritz Stern was made an honorary member of the local Society of Natural Scientists.
- Stern remained extraordinarily healthy and engaged in mathematical and philological research until his death.
- Nowadays Stern is primarily remembered for the fact that he was the first non-baptised Jewish university professor in Germany and not for his mathematical work.
- Nevertheless Stern published numerous papers in various German, French and Belgian journals, as well as in Acta Mathematica.
- Stern also translated Poisson's Lehrbuch der Mechanik (1835-36) and wrote his own textbook Lehrbuch der algebraischen Analysis Ⓣ(Textbook of algebraic Analysis) (1860).
- Stern was made an honorary member of the Physics Society of Frankfurt in 1855.
- One of Stern's papers that is of particular interest is Sur une assertion de Goldbach relative aux nombres impairs Ⓣ(On Goldbach's assertion about odd numbers) (Nouvelles annals de mathématiques, 1854).
- These primes are known as Stern primes.
- Since 1 was considered a prime in Stern's lifetime, the list of Stern primes can be extended to include 2 and 3 as well.
- In his paper Über eine zahlentheoretische Funktion Ⓣ(On a number theoretic function) (Crelle, 1858) Stern described the mathematics behind what is now called the Stern-Brocot tree.
- However Stern used continued fractions to describe the relations between the individual vertices of the tree rather than mediants, and he studied how mediants are related to the Euclidean algorithm.
- Taking all entries in the first iii levels of the tree together with the two initial parents 0/1 and 1/0 gives the Stern-Brocot sequence of order iii.
- In 1860 the French clockmaker Achille Brocot (1817-1878) discovered the tree independently of Stern.
- He had more practical applications in mind than Stern though, as he constructed the tree in order to choose the ratio of gears in watches.

Born 29 June 1807, Frankfurt am Main, Germany. Died 30 January 1894, Zürich, Switzerland.

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Origin Germany

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