Paolo Ruffini (22 September 1765 – 10 May 1822) was an Italian mathematician and philosopher.

Education and career

By 1788 he had earned university degrees in philosophy, medicine/surgery and mathematics. His works include developments in algebra: He also wrote on probability and the quadrature of the circle. He was a professor of mathematics at the University of Modena and a medical doctor including scientific work on typhus.

Group theory

In 1799 Ruffini marked a major improvement for group theory, developing Joseph-Louis Lagrange's work on permutation theory ("Réflexions sur la théorie algébrique des équations", 1770–1771). Lagrange's work was largely ignored until Ruffini established strong connections between permutations and the solvability of algebraic equations. Ruffini was the first to assert, controversially, the unsolvability by radicals of algebraic equations higher than quartics, which angered many members of the community such as Gian Francesco Malfatti (1731–1807). Work in that area was later carried on by those such as Abel and Galois, who succeeded in such a proof.

Publications