No abstract

In this paper, we model any nonconvex quadratic program having a mix of binary and continuous variables as a linear program over the dual of the cone of copositive matrices. This result can be viewed as an extension of earlier separate results, which have established the copositive representation of a small collection of NP-hard problems. A simplification, which reduces the dimension of the linear conic program, and an extension to complementarity constraints are established, and computational issues are discussed.

The low-rank semidefinite programming problem (LRSDP r ) is a restriction of the semidefinite programming problem (SDP) in which a bound r is imposed on the rank of X, and it is well known that LRSDP r is equivalent to SDP if r is not too small. In this paper, we classify the local minima of LRSDP r and prove the optimal convergence of a slight variant of the successful, yet experimental, algorithm of Burer and Monteiro [6], which handles LRSDP r via the nonconvex change of variables X = RR T . In addition, for particular problem classes, we describe a practical technique for obtaining lower bounds on the optimal solution value during the execution of the algorithm. Computational results are presented on a set of combinatorial optimization relaxations, including some of the largest quadratic assignment SDPs solved to date.