Børge Christian Jessen was a Danish mathematician best known for his work in analysis, specifically on the Riemann zeta function, and in geometry, specifically on Hilbert's third problem.
Jessen (right) with Werner Fenchel, A.D. Alexandrov and Herbert Busemann in 1954
Jessen's icosahedron, sometimes called Jessen's orthogonal icosahedron, is a non-convex polyhedron with the same numbers of vertices, edges, and faces as the regular icosahedron. It is named for Børge
Børge Jessen
…Copenhagen. He was also active in the Danish Mathematical Society. After his death, the society named an award in his honor (Børge Jessen Diploma Award). Jessen's icosahedron Jessen–Wintner theorem…
Het Ding [nl], a tensegrity sculpture whose struts and cables form the outline of Jessen's icosahedron, at the University of Twente