Israel Gelfand - Work

Work

Gelfand is known for many developments including:

• the book Calculus of Variations (1963), which he co-authored with Sergei Fomin
• the Gelfand representation in Banach algebra theory;
• the Gelfand–Mazur theorem in Banach algebra theory;
• the Gelfand–Naimark theorem;
• the Gelfand–Naimark–Segal construction;
• Gelfand–Shilov spaces
• the Gelfand–Pettis integral;
• the representation theory of the complex classical Lie groups;
• contributions to the theory of Verma modules in the representation theory of semisimple Lie algebras (with I.N. Bernstein and S.I. Gelfand);
• contributions to distribution theory and measures on infinite-dimensional spaces;
• the first observation of the connection of automorphic forms with representations (with Sergei Fomin);
• conjectures about the Atiyah–Singer index theorem;
• Ordinary differential equations (Gelfand–Levitan theory);
• work on calculus of variations and soliton theory (Gelfand–Dikii equations);
• contributions to the philosophy of cusp forms;
• Gelfand–Fuks cohomology of foliations;
• Gelfand–Kirillov dimension;
• integral geometry;
• combinatorial definition of the Pontryagin class;
• Coxeter functors;
• general hypergeometric functions;
• Gelfand - Tsetlin patterns;
• and many other results, particularly in the representation theory for the classical groups.