The Department of Mathematical Sciences has an active group with interests in discrete mathematics, matroid theory, combinatorial optimization, graph theory, extremal combinatorics, and probabilistic methods. Each year the department offers five or six combinatorics and optimization courses at the junior, senior, and graduate levels. These courses cover the methods, the models, and the theory of discrete optimization, linear programming, and graph theory. In alternate semesters, special topics courses in combinatorics and optimization are offered at the graduate level. Recent topics have included extremal combinatorics, convex polytopes, matroid theory, algebraic combinatorics, and linear optimization. In addition there is a weekly seminar on combinatorics and optimization - recent themes have included: Erdős-Ko-Rado theorems, chip-firing and the critical group, König-Egerváry graphs and their relatives, and distinguishing chromatic numbers. Most years, two or three prominent researchers from academia or industry visit our department to give invited lectures and consult.