Title: Network Security and Emergency Preparedness: The Defensive Domination Model
Speaker: Dr. Tınaz Ekim (Boğaziçi University, Department of Industrial Engineering)
Date: 13/11/2026
Time: 13:30
Place: EA 302
Abstract : The Defensive Domination problem provides a modeling framework that substantially extends the expressive power of classical domination problems, with applications in network security and disaster preparedness. It captures scenarios in which security threats or requests for aid may arise simultaneously at any k>1 nodes of a network (called a k-attack), without prior knowledge of their locations, and where all such threats must be countered effectively. Each defender, representing a security unit or emergency response team, can assist at most one threatened node. Consequently, for every possible k-attack scenario, there must exist a feasible assignment of defenders to the attacked nodes.
Defensive domination is considerably more challenging than classical domination. We first discuss its computational complexity in general settings. We then present polynomial-time solvable cases for several important graph classes. From an optimization perspective, we outline a heuristic algorithm and an exact Benders decomposition approach developed in our recent work.
We conclude with future research directions, including extending the concept of defensive domination to dynamic models that evolve over a time horizon. These variants could incorporate capacitated defenders, attacks of varying severity, or allow all guards – not just the one responding to an attack – to move, ensuring strategic positioning for subsequent threats.
Bio: Tınaz Ekim received B.Sc. degrees in Mathematics from the University of Lille 1 (1999) and in Industrial Engineering from Galatasaray University (2001), and an M.Sc. degree in Scientific Methods in Business from Dauphine University (2002). She earned her Ph.D. in Operations Research from the Swiss Federal Institute of Technology (EPFL) in 2006, where she subsequently conducted postdoctoral research. Since 2007, she has been a faculty member in the Department of Industrial Engineering at Boğaziçi University, where she is a Full Professor. She has served as principal investigator on 3 international and 9 national research grants, and has participated in international collaborative projects, including a Horizon Europe Marie Skłodowska-Curie Actions – Staff Exchanges project. She has authored more than 50 peer-reviewed journal articles, with publications in leading journals such as European Journal of Operational Research, INFORMS Journal on Computing, Discrete Applied Mathematics, and Theoretical Computer Science. Her research interests include Algorithmic Graph Theory and its Applications, Combinatorial Optimization, and Operations Research. She received the Turkish Academy of Sciences’ Outstanding Young Scientists Award (TÜBA-GEBİP) in 2016 and was a Fulbright Visiting Scholar in the US in 2017–2018.