Full Professor in Bonn, 1921–1933

Mathematics in Bonn underwent some significant changes both during the war and in its aftermath. Shortly before the death of Franz London in 1917, Hans Hahn was called as his successor. In early 1921, though, Hahn accepted an attractive offer from the University of Vienna, where he became one of the leading members of the famous Vienna Circle. In this new situation, Eduard Study hoped to bring Hausdorff back to Bonn as Hahn’s successor, much as he had largely engineered his earlier appointment more than a decade earlier. In the meantime, however, circumstances had changed, even though Study remained the key figure in Bonn mathematical circles. By now, younger talents had emerged, mathematicians whose accomplishments were in some respects comparable to Hausdorff’s own. Another novel development in Bonn, entirely absent during the years when London taught there, concerned internal frictions and outright factionalism. Both of these circumstances played a role in the process of choosing candidates to succeed Hans Hahn, and although Study’s favorite ultimately prevailed, Hausdorff’s appointment signaled the end of harmonious relations between the mathematicians in Bonn. To appreciate how the atmosphere changed, though, first requires a glance backward to events in Bonn during the period after Hausdorff had departed for Greifswald in 1913.