Daniel J. Kleitman (born October 4, 1934) is a professor of applied mathematics at MIT. His research interests include combinatorics, graph theory, genomics, and operations research.
Kleitman was born in New York, New York in 1934. received his PhD in Physics from Harvard University in 1958 under Nobel Laureates Julian Schwinger and Roy Glauber. He is the "k" in G. W. Peck, a pseudonym for a group of six mathematicians that includes Kleitman. Formerly a physics professor at Brandeis University, Kleitman was encouraged by Paul Erdős to change his field of study to mathematics. Perhaps humorously, Erdős once asked him, "Why are you only a physicist?"
Kleitman joined the applied mathematics faculty at MIT in 1966, and was promoted to professor in 1969.
Kleitman coauthored at least six papers with Erdős, giving him an Erdős number of 1.
He was a math advisor and extra for the film Good Will Hunting. Since Minnie Driver, who appeared in Good Will Hunting, also appeared in Sleepers with Kevin Bacon, Kleitman has a Bacon number of 2. Adding the two numbers results in an Erdős–Bacon number of 3, tied for lowest currently.
"On a combinatorial problem of Erdős". Proc. Amer. Math. Soc. 17: 139–141. 1966. MR 0184866. doi:10.1090/s0002-9939-1966-0184866-9. "On Dedekind's problem: The number of monotone Boolean functions". Proc. Amer. Math. Soc. 21: 677–682. 1969. MR 0241334. doi:10.1090/s0002-9939-1969-0241334-6. with B. Rothschild: "The number of finite topologies". Proc. Amer. Math. Soc. 25: 276–282. 1970. MR 0253944. doi:10.1090/s0002-9939-1970-0253944-9. with P. Erdős: "On collections of subsets containing 4-member Boolean algebras". Proc. Amer. Math. Soc. 28: 87–90. 1971. MR 0270924. doi:10.1090/s0002-9939-1971-0270924-9. with B. Rothschild: "Asymptotic enumeration of partial orders on a finite set". Trans. Amer. Math. Soc. 205: 205–220. 1975. MR 0369090. doi:10.1090/s0002-9947-1975-0369090-9. with G. Markowsky: "On Dedekind's problem: The number of isotone Boolean functions. II.". Trans. Amer. Math. Soc. 213: 373–390. 1975. MR 0382107. doi:10.1090/s0002-9947-1975-0382107-0. with B. Rothschild and Joel H. Spencer: "The number of semigroups of order n". Proc. Amer. Math. Soc. 55 (1): 227–232. 1976. MR 0414380. doi:10.1090/s0002-9939-1976-0414380-0. with Gil Kalai: "A quasi-polynomial bound for the diameter of graphs of polyhedra". Bull. Amer. Math. Soc. (N.S.). 26 (2): 315–316. 1992. MR 1130448. doi:10.1090/s0273-0979-1992-00285-9. with Noga Alon: "Piercing convex sets". Bull. Amer. Math. Soc. (N.S.). 27 (2): 252–256. 1992. MR 1149871. doi:10.1090/s0273-0979-1992-00304-x. with Alex Coventry and Bonnie Berger: "MSARI: Multiple sequence alignments for statistical detection of RNA secondary structure". Proc Natl Acad Sci U S A. 101 (33): 12102–12107. 2004. PMC 514400 . PMID 15304649. doi:10.1073/pnas.0404193101. 
