Basic counting: sum rule, product rule, selection problems, occupancy problems, binomial coefficients, Stirling numbers
Generating functions: ordinary and exponential generating functions, applications to counting
Recurrences: Fibonacci numbers, derangements, the method of characteristic roots, solving recurrences with generating functions
Principle of inclusion-exclusion
Pigeonhole principle, non-constructive proofs, parity arguments.
Introduction to graph theory: quick overview of fundamental concepts, connectedness, graph coloring, trees; Cayley’s theorem on the number of trees
Brief introduction to Ramsey theory