Jon Folkman

Jon Hal Folkman (8 December 1938 to 23 January 1969) was an American mathematician and a researcher at the RAND Corporation. A Putnam Fellow in 1960, he received his doctorate from Princeton University in 1964 under John Milnor. He contributed theorems across combinatorics: pioneering studies of oriented matroids, a proof of a conjecture of Gian-Carlo Rota on the homology of geometric lattices, the first study of semi-symmetric graphs, which gave the Folkman graph its name, and a Ramsey-type result on graphs with no large complete subgraph. With his colleague Lloyd Shapley he proved the Shapley-Folkman lemma and theorem, which show that sums of sets are approximately convex and which economists use to explain approximate equilibria. Folkman theorem in additive combinatorics was named in his memory by his friends. He died young, in 1969.