3. Concavity and convexity 3.1 Concave and convex functions of a single variable 3.2 Quadratic forms 3.2.1 Quadratic forms: definitions 3.2.2 Quadratic forms: conditions for definiteness 3.2.3 Quadratic forms: conditions for semidefiniteness 3.3 Concave and convex functions of many variables 3.4 Quasiconcavity and quasiconvexity
