M392C NOTES: MORSE THEORY ARUN DEBRAY DECEMBER 5, 2018 These notes were taken in UT Austin’s M392C (Morse Theory) class in Fall 2018, taught by Dan Freed. I live-TEXed them using vim, so there may be typos; please send questions, comments, complaints, and corrections to
[email protected]. Any mistakes in the notes are my own. Contents 1. Critical points and critical values: 8/29/181 2. Sublevel sets: 9/5/18 6 3. : 9/5/18 9 4. Handles and handlebodies: 9/12/189 5. Handles and Morse theory: 9/12/18 11 6. Morse theory and homology: 9/26/18 13 7. Knots and total curvature: 9/26/18 16 8. Submanifolds of Euclidean space: 10/1/18 18 9. Critical submanifolds: 10/3/18 21 10. The Lefschetz hyperplane theorem: 10/3/18 23 11. The h-cobordism theorem: introduction: 10/10/18 26 12. The h-cobordism theorem: 10/10/18 29 13. The stable and unstable manifolds: 10/17/18 32 14. Calculus on Banach spaces: 10/24/18 34 15. The second cancellation theorem: 10/24/18 37 16. Some infinite-dimensional transversality: 10/31/18 38 17. Cancellation in the middle dimensions: 10/31/18 39 18. : 11/7/18 41 19. : 11/14/18 41 20. The h-cobordism theorem and some consequences: 11/19/18 41 21. Geodesics: 11/19/18 43 22. Geodesics, length, and metrics: 11/28/18 45 23. Some applications of geodesics: 12/5/18 49 Lecture 1. Critical points and critical values: 8/29/18 “The victim was a topologist.” (nervous laughter) In this course, manifolds are smooth unless assumed otherwise.