Eva K. Lee
and John E. Mitchell
December 1996
An interior-point algorithm within a branch-and-bound framework for solving nonlinear mixed integer programs is described. In contrast to solving the relaxation to optimality at each tree node, the relaxation is only solved to near-optimality. Analogous to using advanced bases for warmstart solutions in the case of linear MIP, a ``dynamic'' collection of warmstart vectors is kept. Computational results on various classes of nonlinear mixed integer programs are presented.