Year 2000 problem | Boundary Waters Canoe Area Wilderness | Boundary Commission | Waring's problem | The Final Problem | The Problem with Popplers | List of Buckinghamshire boundary changes | Interstellar Boundary Explorer | Hume and the Problem of Causation | Dirichlet problem | Boolean satisfiability problem | The Dog Problem | Tammes problem | Species problem | Regional District of Kootenay Boundary | problem solving | Problem gambling | Packing problem | packing problem | Oregon boundary dispute | List of Berkshire boundary changes | chess problem | Boundary-Similkameen | Boundary marker | Boundary Dam | boundary (cricket) | Boundary Creek | boundary | Znám's problem | Year 10,000 problem |
He also substantially contributed to the development of the theory of capacities, nonlinear potential theory, the asymptotic and qualitative theory of arbitrary order elliptic equations, the theory of ill-posed problems, the theory of boundary value problems in domains with piecewise smooth boundary.
He obtained his PhD in 1963 from the Courant Institute of Mathematical Sciences at New York University; his thesis was entitled A Boundary Value Problem Arising in the Theory of Univalent Functions and was supervised by Paul Garabedian.