

\titleofpresentation{From FLT to Finite Groups.\\
The remarkable career of Otto Gr\"un.}

\presenter{Peter Roquette}

Students who start to learn group theory will soon be confronted with
the theorems of Gr\"un (or some generalization). Immediately
after publication in the mid 1930s \cite{roquette1} these theorems found
their way into group theory textbooks~\cite{roquette2}, and they turned
out to be of fundamental importance in connection with the classical
Sylow theorems. But little is known about the mathematician whose name
is connected with those theorems.

In my talk I shall report on the remarkable mathematical career of
Otto Gr\"un. The talk will be based largely on the letters which were
exchanged between Otto Gr\"un and Helmut Hasse. I found 50 such letters in
the archives of the University of G\"ottingen, from 1932 to 1972. They
document the fascinating story of a mathematician, quite rare in our
time, who was completely self-educated, without having attended
university, and nevertheless succeeded, starting at age 44, to give
important contributions to mathematics, in particular to group theory.
Gr\"un's first papers are concerned with class field theory around
Fermat's Last Theorem (FLT). It was Hasse who pointed out to him
the group theoretical problems in this connection, which then turned
Gr\"un's main interest to group theory.

We shall mention several documents about Gr\"un which were found after
publication of our paper \cite{roquette3}.

\begin{ourbiblio}{99}

\bibitem{roquette1} Gr{\"u}n, O. \emph{Beitr{\"a}ge zur
Gruppentheorie I.} J. Reine Angew. Math. 174 (1935) 1-14
\bibitem{roquette2} Zassenhaus, H. \emph{Lehrbuch der Gruppentheorie.}
Teubner Leipzig (1937)
\bibitem{roquette3} Roquette, P. \emph{From FLT to finite groups.}
Jber. DMV 107 (2005) 117-154

\end{ourbiblio}

\presenteraddress{Heidelberg University}

\email{roquette@uni-hd.de}

\web{www.roquette.uni-hd.de}

