David Sumner

{{short description|American mathematician}}

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,{{citation

| last1 = Kühn | first1 = Daniela | author1-link = Daniela Kühn

| last2 = Mycroft | first2 = Richard

| last3 = Osthus | first3 = Deryk

| arxiv = 1010.4430

| doi = 10.1112/plms/pdq035

| issue = 4

| journal = Proceedings of the London Mathematical Society | series = Third Series

| mr = 2793448 | zbl=1218.05034

| pages = 731–766

| title = A proof of Sumner's universal tournament conjecture for large tournaments

| volume = 102

| year = 2011| s2cid = 119169562 }}. and showed in 1974 that all claw-free graphs with an even number of vertices have perfect matchings.{{Citation

| last1 = Faudree | first1 = Ralph | author1-link = Ralph Faudree

| last2 = Flandrin | first2 = Evelyne

| last3 = Ryjáček | first3 = Zdeněk

| doi = 10.1016/S0012-365X(96)00045-3

| mr = 1432221

| issue = 1–3

| journal = Discrete Mathematics

| pages = 87–147

| title = Claw-free graphs — A survey

| volume = 164

| year = 1997| doi-access = free

}}. 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.{{mathgenealogy|id=7998}} He is a distinguished professor emeritus at the University of South Carolina.{{citation|url=http://www.math.sc.edu/david-sumner|title=Faculty & Staff Directory: David Sumner|publisher=University of South Carolina Department of Mathematics|accessdate=2015-08-30}}.