Minkowski was born in Russia, but lived and worked mostly in Germany and Switzerland. He received his doctorate degree in 1884 from the University of Königsberg, and taught at universities in Bonn, Königsberg, Zurich, and Göttingen. He perhaps best known for his work on the 4–dimensional space time continuum, that later provided a basis for Albert Einstein's general theory of relativity. In mathematics, Minkowski worked on quadratic forms, continued fractions and geometrical packing problems. Students of analysis remember Minkowski for the inequality that bears his name, relating the norm of a sum to the sum of the norms.