About Felix Hausdorff
Wikipedia Biographical Summary:
"...Felix Hausdorff (November 8, 1868 – January 26, 1942) was a German mathematician who is considered to be one of the founders of modern topology and who contributed significantly to set theory, descriptive set theory, measure theory, function theory, and functional analysis.
Hausdorff's father, the Jewish merchant Louis Hausdorff (1843-1896), moved in the autumn of 1870 with his young family to Leipzig and worked over time at various companies, including a linen-and cotton goods factory. He was an educated man and had become a Morenu at the age of 14. There are several treatises from his pen, including a long work on the Aramaic translations of the Bible from the perspective of Talmudic law.
Hausdorff's mother, Hedwig (1848-1902), who is also referred to in various documents as Johanna, came from the Jewish Tietz family. From another branch of this family came Hermann Tietz, founder of the first department store, and later co-owner of the department store chain called "Hermann Tietz". During the period of Nazi dictatorship the name was "Aryanised" to Hertie.
From 1878 to Felix Hausdorff attended the Nicolai School in Leipzig, a facility that had a reputation as a hotbed of humanistic education. He was an excellent student, class leader for many years and often recited self-written Latin or German poems at school celebrations. In his graduation in 1887 (with two Oberprimen), he was the only one who reached the highest grade.
The choice of subject was not easy for Hausdorff. Magda Dierkesmann, who was often a guest in the home of Hausdorff as a student in Bonn in the years 1926-1932, reported in 1967 that:
"His versatile musical talent was so great that he only the insistence of his father made him give up his plan to study music and become a composer."
The decision was made to study the sciences in high school.
From summer term 1887 to summer semester 1891 Hausdorff studied mathematics and astronomy, mainly in his native city of Leipzig, interrupted by one semester in Freiburg (summer semester 1888) and Berlin (winter semester 1888/1889). The surviving testimony of other students show him as extremely versatile interested young man, who, in addition to the mathematical and astronomical lectures, attended lectures in physics, chemistry and geography, and also lectures on philosophy and history of philosophy as well as on issues of language, literature and social sciences. In Leipzig he heard lectures on the history of music from musicologist Paul. His early love of music lasted a lifetime; in Hausdorff's house there were impressive musical evenings with the landlord at the piano, according to witness statements made by various participants. Even as a student in Leipzig, he was an admirer and connoisseur of the music of Richard Wagner.
In later semesters of his studies, Hausdorff was close to Heinrich Brun (1848-1919). Bruns was professor of astronomy and director of the observatory at the University of Leipzig. Under him, Hausdorff graduated in 1891 with a work on the theory of astronomical refraction of light in the atmosphere. Two publications on the same subject followed, and in 1895 his habilitation also followed with a thesis on the absorbance of light in the atmosphere. These early astronomical work Hausdorff have - despite their excellent mathematical working through - not gained importance. Firstly, the underlying idea of Brunswick has not proved viable (there were needs for refraction observations near the astronomical horizon, which - as Julius Bauschinger could show a little later - in principle can not be obtained with the required accuracy). On the other hand, the progress in the direct measurement of atmospheric data (balloon ascents) has soon made the painstaking accuracy of this data from refraction observations unnecessary. In the time between PhD and habilitation Hausdorff completed the yearlong-volunteer military requirement and worked for two years as a computer at the observatory in Leipzig ..."
"...In December 1901 Hausdorff was appointed as adjunct associate professor at the University of Leipzig..."
"...In the summer of 1912 he also began work on his magnum opus, the book "Basics of set theory". It was completed in Greifswald, where Hausdorff had been appointed for the summer semester as full professor in 1913, and was released in April 1914.
The University of Greifswald was the smallest of the Prussian universities. Also, the mathematical institute was small; in the summer semester 1916 and winter semester 1916/17 Hausdorff was the only mathematician in Greifswald. This brought with it that he was almost fully occupied in teaching the basic courses. It was a substantial improvement of his academic situation when Hausdorff was appointed in 1921 to Bonn. Here he could develop a thematically wide-spanned teaching and always lecture on the latest research. He gave a particularly noteworthy lecture on probability theory (NL Hausdorff: Capsule 21: Fasz 64) in the summer semester 1923, in which he grounded this theory in measure-theoretic axiomatic theory, and this occurred ten years before AT Kolmogorov's "Basic concepts of probability theory" (reprinted in full in the collected works, Volume V). In Bonn, Hausdorff had Eduard Study, and later with Otto Toeplitz, outstanding mathematicians as well as colleagues and friends..."