Nikolaus Hofreiter

Nikolaus Hofreiter (born May 8, 1904 in Linz - Urfahr ; † January 23, 1990 ) was an Austrian mathematician who mainly dealt with number theory.

Life

Nikolaus Hofreiter, whose mother brought a leather factory into the family, attended the secondary school in Linz and from 1923 studied in Vienna with Hans Hahn , Wilhelm Wirtinger , Emil Müller (at the Technical University of Vienna on descriptive geometry) and Philipp Furtwängler , with whom he worked in 1927 PhD was awarded with a thesis on the reduction theory of quadratic forms ( a new reduction theory for definite quadratic forms ). In 1928 he passed the teaching examination and also completed the probationary year as a teacher in Vienna, but then went back to the university (first as a research assistant at the TU Vienna), where he became an assistant at Furtwängler in 1929 and completed his habilitation in 1933 . Even then, he was considered an excellent teacher and gave lectures not only in Vienna, but also in Graz .

In his dissertation and habilitation thesis he deals with the reduction theory of square shapes, which, according to Gauss , was dealt with in particular by Charles Hermite and Hermann Minkowski . Hofreiter treated the four-variable case of a problem by Minkowski (which Minkowski had solved for two and Robert Remak for three variables) about the product of inhomogeneous linear forms and made important advances, the complete solution was not achieved until 15 years later (and the general case is up to unsolved today). In 1934, in number theory, he also proved the existence of an infinite number of real-quadratic number fields without a Euclidean algorithm . He also worked on the geometry of numbers and Diophantine approximations .

In 1939 he became an associate professor and married the mathematician Margarete Dostalik (1912–2013), who was also a student of Furtwängler, where she passed the teaching examination and received her doctorate with an important thesis on algebraic equations . At that time she was working as a meteorologist in Berlin . During the Second World War he had to enter Vienna in 1939 and was later transferred to the Hermann Göring Aviation Research Institute in Braunschweig , where his colleague Wolfgang Gröbner from Vienna, Bernhard Baule from Graz, Ernst Peschl and Josef Laub were already . He also managed to get his wife Margarete there. Inspired by practical work in aviation research, the idea arose here to publish an integral table together with Gröbner . The first part of the indefinite integral appeared in Braunschweig as an emergency print in 1944 and by Springer in 1949; 1950 followed the more difficult second part definite integrals . The tables were widely used up to the 5th edition in 1973/75. His wife Margarete checked both parts of the integral table by means of control calculations, while Laub also helped set up and check the formulas and wrote the final fair copy.

Hofreiter and Gröbner were able to hold lectures and seminars at the aviation research institute in addition to their work, and later also at the TU Braunschweig . After the war he returned to Vienna in 1946 and was able to immediately resume lecturing and continue his work on number theory, but increasingly he turned to linear optimization and numerical mathematics . In 1954 he became a full professor, in 1963/64 dean of the faculty and in 1965/66 he was rector of the University of Vienna . In 1974 he retired , but continued to give lectures, mainly on descriptive geometry and introductions to programming.

In 1970 he became a corresponding member of the Austrian Academy of Sciences . He received the Cross of Honor for Science and Art First Class , the Gold Medal of Honor of the Federal Capital Vienna , the Great Silver Medal of Honor for Services to the Republic of Austria , the Commander's Cross of the Order of Gregory and the Ring of Honor of the Austrian Mathematical Society. He was also an honorary senator of the University of Linz. He was buried at the Ober Sankt Veiter cemetery .

His doctoral students include Erich Bukovics , Edmund Hlawka , Peter Gruber , Leopold Butterer and Fritz Schweiger .

Individual evidence

1. ↑ List of all decorations awarded by the Federal President for services to the Republic of Austria from 1952 (PDF file; 6.59 MB)
2. ↑ Nikolaus Hofreiter grave site , Vienna, Ober Sankt Veiter Friedhof, Group J, Row 15, No. 11.
3. ↑ Nikolaus Hofreiter in the Mathematics Genealogy Project (English)

literature

• Edmund Hlawka : Nikolaus Hofreiter. In: Almanac of the Austrian Academy of Sciences for 1989/90. 140th year, Vienna 1990, pp. 327-340.
• Edmund Hlawka: Obituary for Nikolaus Hofreiter . In: Monthly books for mathematics . Volume 116, 1993, No. 3-4, pp. 263-273

Web links

• Biography, PDF (18 kB)
• Biography, House of Mathematics
• Nikolaus Hofreiter in the Mathematics Genealogy Project (English)