Ernst Sigismund Fischer

Ernst S. Fischer
ca. 1920
Born(1875-07-12)12 July 1875
Died14 November 1954(1954-11-14) (aged 79)
NationalityAustrian
Alma materUniversity of Vienna
Known forRiesz–Fischer theorem
Fischer's inequality
SpouseEllis Strauss
ChildrenUrsula
Scientific career
FieldsMathematics
InstitutionsUniversity of Cologne
Thesis Zur Theorie der Determinanten  (1899)
Doctoral advisorFranz Mertens
Leopold Gegenbauer

Ernst Sigismund Fischer (12 July 1875 – 14 November 1954) was a mathematician born in Vienna, Austria. He worked alongside both Mertens and Minkowski at the Universities of Vienna and Zurich, respectively. He later became professor at the University of Erlangen, where he worked with Emmy Noether.

His main area of research was mathematical analysis, specifically orthonormal sequences of functions, which laid groundwork for the emergence of the concept of a Hilbert space.

The Riesz–Fischer theorem in Lebesgue integration is named in his honour.

He is the grandson of composer Karl Graedener.[1][2]

  1. ^ Ernst Sigismund Fischer http://www-history.mcs.st-andrews.ac.uk/Biographies/Fischer.html.
  2. ^ Sur la convergence en moyenne und Applications d'un théorème sur la convergence en moyenne, Comptes rendus Acad.Science, 1907