Convex cone Convex function Convex set Legendre–Fenchel transformation Convex minimization Fenchel's duality theorem Geometry Convex geometry Brunn–Minkowski theorem Differential geometry Fenchel's theorem Hyperbolic geometry Jakob Nielsen Fenchel–Nielsen coordinates Nonlinear programming References External links Werner Fenchel website – contains CV, biography, links to archive, etc. Geometers Differential geometers 20th-century German mathematicians Danish mathematicians Jewish emigrants from Nazi Germany to Denmark 1905 births 1988 deaths Variational analysts