Research Interests

Informatics Problems in Chemistry, Biology, and Medicine
With the recent accumulation of vast amounts of chemical, biological, and clinical data, many scientific fields are becoming increasingly data-driven as opposed to model-driven. This paradigm shift has brought about many challenging computational problems. Even though these problems originate from very disparate fields, they have very similar mathematical structures. In particular, they involve the use of a merit function to evaluate alternatives from very large, typically combinatorial, search spaces. Professor Sahinidis’ work in this area provides comprehensive and rigorous solutions to inverse imaging problems in X-ray crystallography, modeling and estimation of dynamic metabolic and signaling pathways, structural bioinformatics, medical diagnosis and prognosis, and the design of novel chemicals that are environmentally benign.

Optimization Theory, Algorithms, and Software
A plethora of problems in science and engineering require the solution of nonlinear optimization problems with multiple local solutions. Professor Sahinidis’ research has recently led to the development of an all-purpose, rigorous global optimization methodology. His results have included the development of a unifying framework for domain reduction; a theory of convex extensions that provides strong relaxations for a variety of mathematical programs; an entirely linear outer-approximation scheme for global optimization problems; finite branching schemes for certain continuous nonconvex problem classes; and the global optimization software BARON. Scientists and engineers have used the BARON software in many application areas, including the development of new Runge-Kutta methods for partial differential equations, energy policy making, modeling and design of metabolic processes, product and process design, engineering design, and automatic control. The ultimate goal of this research thrust is to provide precise and valuable computational optimization tools that will allow engineers and scientists to solve problems that are currently considered intractable. Towards this end, projects pursue fundamental advances in linear and nonlinear optimization, and the development of advanced computing technologies for optimization.

Representative Publications

Xie, W. and N. V. Sahinidis, A reduction-based exact algorithm for the contact map overlap problem, Journal of Computational Biology, 14(5), 637–654, 2007.

Tawarmalani, M. and N. V. Sahinidis, A polyhedral branch-and-cut approach to global optimization, Mathematical Programming, Ser. B, 103, 225-249, 2005.

Ahmed, S. and N. V. Sahinidis, An approximation scheme for stochastic integer programs arising in capacity expansion, Operations Research, 51(3), 461-471, 2003.

Shectman, J. P. and N. V. Sahinidis, A finite algorithm for global minimization of separable concave programs, Journal of Global Optimization, 12(1), 1-36, 1998.

Sahinidis, N. V. and I. E. Grossmann, MINLP model for cyclic multiproduct scheduling on continuous parallel lines, Computers & Chemical Engineering, 15(2), 85-103, 1991.