David Sumner

David P. Sumner is an American mathematician known for his research in graph theory. He formulated Sumner's conjecture that tournaments are universal graphs for polytrees in 1971,^[1] and showed in 1974 that all claw-free graphs with an even number of vertices have perfect matchings.^[2] He and András Gyárfás independently formulated the Gyárfás–Sumner conjecture according to which, for every tree T, the T-free graphs are χ-bounded.

Sumner earned his doctorate from the University of Massachusetts Amherst in 1970, under the supervision of David J. Foulis.^[3] He is a distinguished professor emeritus at the University of South Carolina.^[4]