Leonid Nisonovich Vaserstein (Russian: Леонид Нисонович Васерштейн) is a Russian-American mathematician, currently Professor of Mathematics at Penn State University.
He is well known for providing a simple proof of the Quillen–Suslin theorem, a result in commutative algebra, first conjectured by Jean-Pierre Serre in 1955, and then proved by Daniel Quillen and Andrei Suslin in 1976.
After his doctoral graduation he worked for the Moscow State University-associated "Informelectro" Institute, a Federal State Unitary Enterprise focused on ways to develop industries in Russia with emphases on electrical engineering, energy efficiency, and environmental technologies like greenhouse gas mitigation.
Vaserstein's research interests extend across the areas of topology, algebra, and number theory, and the applications of these areas, including classical groups over rings, algebraic K-theory, systems with local interactions, and optimization and planning.
Additionally, Vaserstein maintains the Penn State University Math Department's website on Algebra and Number Theory.