Preface.- Notes on the Life and Work of A. Grothendieck.- Characteristic Classes of Singular Varieties.- Lectures on the Geometry of Flag Varieties.- Combinatorial K-Theory.- Morse Functions and Cohomology of Homogeneous Spaces.- Integrable Systems and Gromov-Witten Theory.- Multiplying Schubert Classes.- Lectures on Characteristic Classes of Constructible Functions.- Algebraic K-Theory of Schemes.- Gromov-Witten Invariants and Quantum Cohomology of Grassmannians.