Julius Wilhelm Richard Dedekind (German: [ˈdeːdəˌkɪnt]; 6 October 1831 – 12 February 1916) was a German mathematician who made important contributions to number theory, abstract algebra (particularly ring theory), and the axiomatic foundations of arithmetic.

He is also considered a pioneer in the development of modern set theory and of the philosophy of mathematics known as logicism.

His mother was Caroline Henriette Dedekind (née Emperius), the daughter of a professor at the Collegium.

At that time, the University of Berlin, not Göttingen, was the main facility for mathematical research in Germany.

Thus Dedekind went to Berlin for two years of study, where he and Bernhard Riemann were contemporaries; they were both awarded the habilitation in 1854.

Dedekind returned to Göttingen to teach as a Privatdozent, giving courses on probability and geometry.

Thus the set N of natural numbers can be shown to be similar to the subset of N whose members are the squares of every member of N, (N → N2): Dedekind's work in this area anticipated that of Georg Cantor, who is commonly considered the founder of set theory.

Likewise, his contributions to the foundations of mathematics anticipated later works by major proponents of logicism, such as Gottlob Frege and Bertrand Russell.

In an 1882 article, Dedekind and Heinrich Martin Weber applied ideals to Riemann surfaces, giving an algebraic proof of the Riemann–Roch theorem.

In 1888, he published a short monograph titled Was sind und was sollen die Zahlen?

The next year, Giuseppe Peano, citing Dedekind, formulated an equivalent but simpler set of axioms, now the standard ones.