Russian mathematician best known for his work on the algebraic aspects of topology. He earned a degree in engineering at the Ecole Centrale in Paris and elected to travel to America when he was 21 years of age. While working at Westinghouse in Pittsburgh, he was in a laboratory accident that cost him both hands. Lefschetz turned to the study of mathematics, and, as a fellow of Clark University, he earned a doctorate in mathematics in 1911. He taught at Nebraska, Kansas, and Princeton universities. He edited the Annals of Mathematics for 30 years and was President of the American Mathematical Society for three years.