Preface: International conference on game theory and optimization, June 6xe2x80x9310, 2016, Indian Institute of Technology Madras, Chennai, India A conferencecumworkshop on Game Theory and Optimization was held at the Indian Institute of Technology Madras, during June 6xe2x80x9310, 2016. One of the primary objectives of the event was to commemorate the 75th birthday of Professor T. Parthasarathy, fondly referred to as TP. A special session was devoted to his life and mathematical career. This provided a platform for many of TPxe2x80x99s students and collaborators to share their experiences with the audience. The conference was made possible through funding from the National Mathematics Initiative. Additional funding was received from the Office of Alumni and International Relations, the Departments of Mathematics, and Management Studies, Indian Institute of Technology Madras (IIT Madras). Following is a brief overview of the contributions to this special issue, a biography of Professor TP, and a list of his publications. The Guest Editors would like to thank all the authors, Annals of Operations Research EditorinChief, Endre Boros, and all referees who provided peer review. This special issue would not have been possible without their valuable time and input.

The subset sum game revisited We discuss a game theoretic variant of the subset sum problem, in which two players compete for a common resource represented by a knapsack. Each player owns a private set of items, players pack items alternately, and each player either wants to maximize the total weight of his own items packed into the knapsack or to minimize the total weight of the items of the other player. We show that finding the best packing strategy against a hostile or a selfish adversary is PSPACEcomplete, and that against these adversaries the optimal reachable item weight for a player cannot be approximated within any constant factor (unless PNP). The game becomes easier when the adversary is shortsighted and plays greedily: finding the best packing strategy against a greedy adversary is NPcomplete in the weak sense. This variant forms one of the rare examples of pseudopolynomially solvable problems that have a PTAS, but do not allow an FPTAS.