The Cosco subgroup on Constraint Reasoning and Optimization group focuses on the development and analysis of state-of-the-art decision, search, and optimization procedures, and their applications in computationally hard problem domains with real-world relevance. The group contributes especially to the development state-of-the-art Boolean satisfiability (SAT) solvers, their extensions to Boolean optimization, and applications of SAT-based and other types of discrete search and optimization procedures in exactly solving intrinsically hard (NP-complete and beyond) computational tasks. Recent domain-specific studies include exactly solving machine learning problems (different types of clustering, classification, and structure learning tasks) via constrained optimization, and computational aspects of argumentation theory.