Studied in Palermo with G. B. Guccia, F. Gerbaldi and E. Cesaro . He took a degree in engineering in 1890 and another in mathematics in 1895. He taught Calculus in Messina (1901-09) where he escaped by chance to the terrible earthquake in 1908, in Palermo (1909-21) and eventually in Roma until his death in 1927.

In 1909 he won the Bordin prize for his work in collaboration with M. de Franchis on hyperelliptic surfaces. He was one of the most distinguished Italian scholars of the end of last century in group theory. He was member of the Accademia Nazionale dei Lincei and hononary professor of the Washington University .

Among his students we may quote M. Cipolla (who was above all an algebraist) and P. Nalli (an analyst in the University of Catania ) who was the first woman to get a chair of full professor in an Italian University .

Main commemorations and studies: F. Severi, *Rend. della R. Acc. Nazionale dei Lincei *, (6), 8, 1928, 12-20; Guido Zappa in *Opere *