A new surrogate dual multiplier search procedure

Efficient computation of tight bounds is of primary concern in any branch-and-bound procedure for solving integer programming problems. Many successful branch-and-bound approaches use the linear programming relaxation for bounding purposes. Significant interest has been reported in Lagrangian and surrogate duals as alternative sources of bounds. The existence of efficient techniques such as subgradient search for solving Lagrangian duals has led to some very successful applications of Lagrangian duality in solving specially structured problems. While surrogate duals have been theoretically shown to provide stronger bounds, the difficulty of surrogate dual-multiplier search has discouraged their employment in solving integer programs. Based on the development of a new relationship between surrogate and Lagrangian duality, we suggest a new strategy for computing surrogate dual values. The proposed approach allows us to directly use established Lagrangian search methods for exploring surrogate dual multipliers. Computational experience with randomly generated capital budgeting problems validates the economic feasibility of the proposed ideas.     

India–Africa defence cooperation against the backdrop of the ‘Make in India’ initiative

Although India is a major importer of defence equipment, it has also been manufacturing defence equipment for some of its needs. The Government of India’s ambitious ‘Make in India’ initiative for the defence sector aims to achieve self reliance in defence equipment production. This essay explores the opportunities for bilateral arms trade between India and Africa, as a new facet of India-Africa defence cooperation. It covers India’s arms export policy, policy reforms in India’s defence sector, and the opportunities for Indian and African defence markets.