Max Wilhelm Dehn (November 13, 1878 – June 27, 1952) was a German mathematician most famous for his work in geometry, topology and geometric group theory.

He studied the foundations of geometry with Hilbert at Göttingen in 1899, and obtained a proof of the Jordan curve theorem for polygons.

In his habilitation at the University of Münster in 1900 he resolved Hilbert's third problem, by introducing what was afterwards called the Dehn invariant.

In the early 1920s Dehn introduced the result that would come to be known as the Dehn-Nielsen theorem; its proof would be published in 1927 by Jakob Nielsen.

[8] As an example of its influence, the seminar has been credited for inspiring Siegel's discovery of the Riemann–Siegel formula among Riemann's unpublished notes.

[9] Dehn stayed in Germany until January 1939, when he fled to Copenhagen, and then to Trondheim, Norway, where he took a position at the Norwegian Institute of Technology.

In March 1944, Dehn was invited to give two talks at Black Mountain College on the philosophy and history of mathematics.

After negotiating his salary from $25 to $40 per month, Dehn and his wife moved into housing provided by the school and he began teaching in January 1945.

[10][3] In his class "Geometry for Artists," Dehn introduced students to geometric concepts such as points, lines, planes and solids; cones sectioned into circles, ellipses, parabolas, and hyperbolas; spheres and regular polyhedrons.

In the summer of 1952 Dehn was made Professor Emeritus, which allowed him to remain on campus and act as an advisor.