Karl Friedrich Wilhelm Rohn (January 25, 1855 in Schwanheim – August 4, 1920 in

Leipzig Leipzig ( , ; Upper Saxon: ) is the most populous city in the German state of Saxony. Leipzig's population of 605,407 inhabitants (1.1 million in the larger urban zone) as of 2021 places the city as Germany's eighth most populous, as wel ...

) was a German

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

, who studied

geometry Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...

Life and work

Rohn studied in

Darmstadt Darmstadt () is a city in the States of Germany, state of Hesse in Germany, located in the southern part of the Frankfurt Rhine Main Area, Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it th ...

and

Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...

, initially engineering but then mathematics by the influence of Alexander von Brill, among the others. In 1878 he received a doctorate under the supervision of Felix Klein in Munich, and in 1879 he habilitated at Leipzig. The subject of his doctoral thesis and habilitation was the

Kummer surface In algebraic geometry, a Kummer quartic surface, first studied by , is an irreducible nodal surface of degree 4 in \mathbb^3 with the maximal possible number of 16 double points. Any such surface is the Kummer variety of the Jacobian variety o ...

s of order 4 and their relationship with

hyperelliptic function In algebraic geometry, a hyperelliptic curve is an algebraic curve of genus ''g'' > 1, given by an equation of the form y^2 + h(x)y = f(x) where ''f''(''x'') is a polynomial of degree ''n'' = 2''g'' + 1 > 4 or ''n'' = 2''g'' + 2 > 4 with ''n'' dis ...

s (with Riemann surfaces of genus 2). In 1884 he became an associate professor at the University of Leipzig and a year later at the Dresden University of Technology, where in 1887 he was a professor of descriptive geometry. In 1904 he became a professor at Leipzig. In addition to the Kummer surfaces, he studied algebraic space curves and completed the classification work of Georges Henri Halphen, Georges Halphen and Max Noether. In 1913 he was the president of the German Mathematical Society.

Writings

* ''Die verschiedenen Gestalten der Kummer'schen Fläche.'' In: ''Mathematische Annalen.'' 18. Band. Leipzig 1881, S. 99–159.
online
* with Erwin Papperitz
''Lehrbuch der Darstellenden Geometrie''
2 Bände, Leipzig 1893, 1896. * with L. Berzolari: ''Algebraische Raumkurven und abwickelbare Flächen.'' In: ''Enzyklopädie der mathematischen Wissenschaften.'' Erschienen 1926.
online

References

The original article was a Google translation of the corresponding German article. * * Siegfried Gottwald, Hans J. Ilgauds, Karl-Heinz Schlote (Eds):'' Encyclopedia of important mathematicians.'' Second Edition. Harri German, Frankfurt am Main 2006, . * Friedrich Schur
''Karl Rohn''
Nachruf. In: ''Jahresbericht der Deutschen Mathematiker-Vereinigung.'' 32. Band, Leipzig 1923, S. 201–211

External links

* * {{DEFAULTSORT:Rohn, Karl 19th-century German mathematicians 1855 births 1920 deaths Technische Universität Darmstadt alumni 20th-century German mathematicians