This special issue contains 18 papers which were selected for publication after a rigorous peer review process. Its aim is to present the recent advances in optimization and problem-solving methods to provide effective solutions to complex decision-making problems. Many submissions were received from the participants to ODS2018 (, the International Conference on Optimization and Decision Science, which was held in Taormina (Messina), Italy, from 10 to 13 September 2018.

These papers cover different topics such as problems of quasi-equilibria, semi-infinite programming, logistics, machine learning problems, set optimization, traffic networks, drone-assisted deliveries, routing, supplier selections, hybrid differential games, horizontal linear complementarity, Generalized Nash equilibria, timetabling, optimal scheduling as well as optimization techniques for battery charges and for trading strategies, splitting methods, and simulated annealing techniques.

We would like to take this opportunity to thank all authors for their submissions and all reviewers for their excellent work and fruitful comments during the editing process of this special issue.

We are deeply grateful to the Editors-in-Chief of Optimization Letters, Prof. O. Prokopyev and Prof. P. Krokhmal for their kind support.

We hope that the reader will find papers of this special issue useful and interesting.

Guest Editors: Patrizia Daniele and Laura R.M. Scrimali