BASIC DISCRETE MATHEMATICS DAVID GALVIN, DEPARTMENT OF MATHEMATICS, UNIVERSITY OF NOTRE DAME Abstract. This document includes lecture notes, homework and exams from the Spring 2017 incarnation of Math 60610 | Basic Discrete Mathematics, a graduate course offered by the Department of Mathematics at the University of Notre Dame. The notes have been written in a single pass, and as such may well contain typographical (and sometimes more substantial) errors. Comments and corrections will be happily received at
[email protected]. Contents 1. Introduction 2 2. Graphs and trees | basic definitions and questions 3 3. The extremal question for trees, and some basic properties 5 4. The enumerative question for trees | Cayley's formula 6 5. Proof of Cayley's formula 7 6. Pr¨ufer's proof of Cayley 12 7. Otter's formula 15 8. Some problems 15 9. Some basic counting problems 18 10. Subsets of a set 19 11. Binomial coefficient identities 20 12. Some problems 25 13. Multisets, weak compositions, compositions 30 14. Set partitions 32 15. Some problems 37 16. Inclusion-exclusion 39 17. Some problems 45 18. Partitions of an integer 47 19. Some problems 49 20. The Twelvefold way 49 21. Generating functions 51 22. Some problems 59 23. Operations on power series 61 24. The Catalan numbers 62 25. Some problems 69 26. Some examples of two-variable generating functions 70 27. Binomial coefficients 71 28. Delannoy numbers 71 29. Some problems 74 30. Stirling numbers of the second kind 76 Date: Spring 2017; version of December 13, 2017. 1 2 DAVID GALVIN, DEPARTMENT OF MATHEMATICS, UNIVERSITY OF NOTRE DAME 31.