Dov Gabbay is the (Emeritus) Augustus de Morgan Professor of Logic at King’s College London, an invited professor at the Université de Luxembourg, a professor at Bar-Ilan University, Israel, and a professor of theoretical computer Science at Ashkelon Academic College, Israel. He is Editor-in-chief of several international journals and handbooks, among them the Handbook of Philosophical Logic. His research interests include logic and computation, proof theory and goal-directed theorem proving, nonclassical logics and nonmonotonic reasoning, labeled deductive systems, fibring logics, and reactive systems. His most recent books include Conditionals and Modularity in General Logics (Springer 2011) and Logical Tools for Handling Change in Agent-Based Systems (Springer 2009). Karl Schlechta is a retired professor of computer science at Aix-Marseille University in France, and a member of the Laboratoire d’Informatique Fondamentale de Marseille. He works on nonmonotonic logics,theory revision, and related subjects, his main interest being the semantical side of these logics and in particular preferential structures and accompanying representation theorems. His books include Coherent Systems (Elsevier 2004), Logical Tools for Handling Change in Agent-Based Systems (Springer 2009), and Conditionals and Modularity in General Logics (Springer 2011).