Semidefinite programming.

• M.X. Goemans and D.P. Williamson, Approximation Algorithms for MAX-3-CUT and Other Problems Via Complex Semidefinite Programming, Proceedings of 33rd STOC, Crete, 443--452, 2001. (The previous link is slightly different from the one from STOC.) Journal version in the STOC 2001 Special Issue of Journal of Computer and System Sciences, 68, 442--470, 2004.

• M.X. Goemans and L. Tuncel, When does the positive semidefiniteness constraint help in lifting procedures, Mathematics of Operations Research, 26, 796-815, 2001.

• M.X. Goemans and F. Rendl, Combinatorial Optimization, in Handbook of Semidefinite Programming: Theory, Algorithms and Applications, H. Wolkowicz, R. Saigal and L. Vandenberghe, Eds., 2000.

• M.X. Goemans and F. Rendl, Semidefinite Programs and Association Schemes, Computing, 63, 331--340, 1999.

• Survey. M.X. Goemans, Semidefinite Programming and Combinatorial Optimization, Documenta Mathematica, Extra Volume ICM 1998, Vol III, 657--666, 1998.

• J. Kleinberg and M.X. Goemans, The Lovasz Theta Function and a Semidefinite Programming Relaxation of Vertex Cover, SIAM Journal on Discrete Mathematics, 11, 196--204, 1998. Reprint.

• Survey. M.X. Goemans, Semidefinite Programming in Combinatorial Optimization, Mathematical Programming, 79, 143--161, 1997.

• U. Feige and M.X. Goemans, Approximating the value of two prover proof systems, with applications to MAX 2SAT and MAX DICUT, Proceedings of the Third Israel Symposium on Theory of Computing and Systems, Tel Aviv, Israel, 182--189, 1995.

• The MAXCUT paper. M.X. Goemans and D.P. Williamson, Improved Approximation Algorithms for Maximum Cut and Satisfiability Problems Using Semidefinite Programming, J. ACM, 42, 1115--1145, 1995. A preliminary version appeared in the Proceedings of the 26th Symposium on the Theory of Computing, Montreal, Canada, 422--431, 1994. Prepint in pdf. This paper received the Fulkerson Prize (in August 2000, see also here or here) awarded jointly between the American Mathematical Society and the Mathematical Programming Society, and also the SIAM Activity group on Optimization Prize (in May 1999) awarded by the Society for Industrial and Applied Mathematics. A few citations (see also here and there and there and there and there and there and there and there).