Axel Harnack (mathematician)

Carl Gustav Axel Harnack (born April 25, ^jul. / 7. May 1851 ^greg. In Tartu , † 3. April 1888 in Dresden ) was a German mathematician who deals with real algebraic geometry , analysis and mathematical physics employed.

Axel Harnack

life and work

Harnack, son of theology professor Theodosius Harnack , studied in Dorpat from 1869 and in Erlangen from 1874 , where he received his doctorate under Felix Klein . In the winter semester of 1875/6 he completed his habilitation in Leipzig , where he was then a private lecturer. From 1876 he was a professor at the Technical University of Darmstadt and from 1877 at the Technical University of Dresden. Since 1885 he was a full member of the Royal Saxon Society of Sciences .

Harnack was a pioneer in real algebraic geometry, where Harnack's theorem (1876) states that a real algebraic curve of the nth order in the projective plane breaks down into at most parts. ${\ displaystyle {\ frac {1} {2}} (n-1) (n-2) +1}$

In potential theory he is known for Harnack's inequalities for harmonic functions . He is also one of the pioneers in the introduction of the concept of measure in analysis (alongside Georg Cantor and Otto Stolz ).

Axel Harnack was the twin brother of the theologian Adolf (von) Harnack ; a younger brother was the pharmacologist Erich Harnack , another younger brother was the literary scholar Otto Harnack . He died in Dresden in 1888 and was buried in the Trinitatisfriedhof .

Fonts

The elements of differential and integral calculus. As an introduction to the course. BG Teubner, Leipzig 1881. archive.org
The basics of the theory of logarithmic potential and the unique potential function in the plane. B. G. Teubner, Leipzig 1887. archive.org
Leibniz 'Significance in the History of Mathematics. v. Zahn & Jaensch, Dresden 1887. archive.org

literature

Gottwald , Ilgauds , Schlote : Lexicon of important mathematicians. 1990.
Moritz Cantor : Harnack, Axel . In: Allgemeine Deutsche Biographie (ADB). Volume 50, Duncker & Humblot, Leipzig 1905, pp. 6-8.

Web links

Overview of the courses given by Axel Harnack (mathematician) at the University of Leipzig (summer semester 1876 to winter semester 1876)
Baltic Historical Commission (ed.): Entry on Axel Harnack. In: BBLD - Baltic Biographical Lexicon digital
A. Voss: In memory of Axel Harnack . In: Mathematische Annalen , Volume 32, 1888, pp. 161-174.
M. Noether: Carl Gustav Axel Harnack . In: Journal for Mathematics and Physics , Volume 33, 1888, Historical-Literary Section, pp. 121–124.
Album academicum of the Imperial University of Dorpat , Dorpat 1889
Harnack, Carl Gustav Axel. Hessian biography. (As of April 3, 2020). In: Landesgeschichtliches Informationssystem Hessen (LAGIS).

Individual evidence

^ Technical University of Dresden (ed.): Graves of professors of the alma mater dresdensis in cemeteries in Dresden and the surrounding area . 2nd Edition. Lausitzer Druck- und Verlagshaus, 2003, p. 43.

personal data
SURNAME	Harnack, Axel
ALTERNATIVE NAMES	Harnack, Carl Gustav Axel (full name)
BRIEF DESCRIPTION	German mathematician
DATE OF BIRTH	May 7, 1851
PLACE OF BIRTH	Dorpat
DATE OF DEATH	April 3, 1888
Place of death	Dresden

[1] Technical University of Dresden (ed.): Graves of professors of the alma mater dresdensis in cemeteries in Dresden and the surrounding area . 2nd Edition. Lausitzer Druck- und Verlagshaus, 2003, p. 43.