Robert V. Kohn

Robert Vita Kohn (October 5, 1953 – January 12, 2026) was an American mathematician who worked on partial differential equations, calculus of variations, mathematical materials science and mathematical finance. He was a professor at the Courant Institute of Mathematical Sciences, New York University.

Background Kohn studied mathematics at Harvard University, obtaining his bachelor's degree in 1974. He obtained his Ph.D. at Princeton University in 1979, as a student of Frederick Almgren.

Kohn died of cancer on January 12, 2026, at the age of 72.

Work Kohn is best known for his work on non-linear partial differential equations, including work with Louis Nirenberg and Luis Caffarelli in which they obtained partial results about the regularity of weak solutions of the Navier–Stokes equations.

Honors Kohn received a Sloan Research Fellowship in 1984. In 2006, he was a plenary speaker at the International Congress of Mathematicians, in Madrid (Energy driven pattern formation). He was a member of the inaugural class of Fellows of the Society for Industrial and Applied Mathematics (SIAM) . He was a fellow of the American Mathematical Society. He was an elected member of American Academy of Arts and Sciences.

Selected publications with L. Caffarelli and L. Nirenberg: "Partial regularity of suitable weak solutions of the Navier–Stokes equations", Communications on Pure and Applied Mathematics, n. 35 i. 6, pp. 771–831. with L. Caffarelli and L. Nirenberg, "First order interpolation inequalities with weights", Compositio Mathematica n. 53 i. 3, pp. 259–275. with Gilbert Strang, "Optimal design and relaxation of variational problems, I", Communications on Pure and Applied Mathematics, n. 39 i. 1, pp. 113–137.