Richard Dedekind is best known for his work in number theory. He redefined irrational numbers, proposing that rational and irrational numbers form a continuum in which real numbers are located by "cuts" in the realm of rational numbers. He also introduced the notion of an ideal (for example, the collection of all integer multiples of a given integer), which allowed wider application of factorizationand is fundamental to modern ring theory. In addition to Dedekind cuts, about a dozen mathematical concepts carry his name. Although he was among the most capable and original mathematicians of his day, Dedekind was a modest man, spending most of his professional life as a teacher at the technical high school in his hometown of Brunswick. He was a gifted teacher, and his teaching was an integral part of his mathematical thinking.

Dedeking was born Julius Wilhelm Richard Dedekind on October 6, 1831, in Brunswick (Braunschweig...