Who was a Hungarian-American mathematician, physicist, and computer scientist that helped introduce a technique for using unbounded operators to study modules generated by a single vector?
John von Neumann John von Neumann ( ; Hungarian: "Neumann János Lajos" , ] ; December 28, 1903 – February 8, 1957) was a Hungarian-American mathematician, physicist, and computer scientist. He made major contributions to a number of fields, including mathematics (foundations of mathematics, functional analysis, ergodic theory, representation theory, operator algebras, geometry, topology, and numerical analysis), physics (quantum mechanics, hydrodynamics, and quantum statistical mechanics), economics (game theory), computing (Von Neumann architecture, linear programming, self-replicating machines, stochastic computing), and statistics.
Nicolae Popescu Nicolae Popescu, Ph.D., D.Phil. (] ; 22 September 1937 – 29 July 2010) was a Romanian mathematician and Emeritus Professor. Popescu was elected a Member of the Romanian Academy in 1992. He is best known for his contributions to Algebra and the theory of Abelian categories. Since 1964 and until 2007 he collaborated on the characterization of abelian categories with the well-known French mathematician Pierre Gabriel. His areas of expertise were: Category theory, Abelian categories with Applications to Rings and Modules, adjoint functors, limits/colimits, Theory of Sheaves, Theory of Rings, Fields and Polynomials, and Valuation Theory; he also had interests and published in the following areas: Algebraic Topology, Algebraic Geometry, Commutative Algebra, K-Theory, Class-Field theory, and Algebraic Function Theory. He published between 1962 and 2008 more than 102 papers in peer-reviewed, mathematics journals, several monographs on the theory of sheaves, and also six books on abelian category theory and abstract algebra. In a Grothendieck-like, energetic style, he initiated and provided scientific leadership to several seminars on category theory, sheaves and abstract algebra which resulted in a continuous stream of high-quality mathematical publications in international, peer-reviewed mathematics journals by several members participating in his Seminar series. His book "Abelian Categories with Applications to Rings and Modules" continues to provide valuable information to mathematicians around the world. His latest contributions have also branched into valuation and number theory. He has published over 110 original, peer-reviewed articles in mathematics, mostly in category theory, algebraic geometry, and Galois and number theory.