BETTI, ENRICO

born Oct. 21, 1823, Pistoia, Tuscany died Aug. 11, 1892, Pisa, Kingdom of Italy mathematician who wrote a pioneering memoir on topology, the study of surfaces and space, and wrote the first rigorous exposition of the theory of equations developed by the noted French mathematician variste Galois (181132). Betti studied at the University of Pisa, where he obtained a chair of mathematics in 1857. His early work was in the theory of equations and algebra. He extended and furnished proofs for Galois's work, which had previously been stated in part without demonstrations or proofs. Betti was the first to resolve integral functions of a complex variable into their primary factors. His later work was decisively affected by the arrival in Pisa of the German mathematician Bernhard Riemann in 1863. They became close friends, and Riemann awakened Betti's interest in mathematical physics, in particular potential theory and elasticity, and inspired his memoir on topology.