Mathematician, born in Königsberg, Germany. He studied at Königsberg and became professor there (1893). He moved to Göttingen in 1895, where he critically examined the foundations of geometry. He made important contributions to the theory of numbers, the theory of invariants and algebraic geometry, and the application of integral equations to physical problems. He later extended his axiomatic approach to geometry to an attempt to base all mathematics on finitely many axioms - an approach shown to be inadequate by Gödel in 1931. At the International Congress of Mathematicians in 1900 he listed 23 problems which he regarded as important for contemporary mathematics; the solutions of many of these have led to interesting advances, while others are still unsolved.