MAT320 LECTURE 5 (9/14/2020): Compact sets





Announcements: Hello! Homework set HW2 is available online, as well as answers to HW1. As always, if you have questions, please send me an email or look for me on Zoom during office hours and I will be happy to discuss the details with you.


• Video 1: Definition of open cover and compact set
Download file or watch below



• Video 2: Compactness is intrinsic: it does not depend on ''ambient'' space
Download file or watch below



• Video 3: Compact subsets are closed
Download file or watch below



• Video 4: Closed subsets of compact sets are compact
Download file or watch below



• Video 5: Intersections of certain families of compact sets are nonempty
Download file or watch below



• Video 6: Intersections of sequences of nested (nonempty) compact sets are nonempty
Download file or watch below



• Video 7: Intersections of sequences of nested (nonempty) closed intervals are nonempty
Download file or watch below



• Video 8: Infinite subsets of compact sets have a limit point
Download file or watch below



• Video 9: Definition of $k$-cell, intersections of sequences of nested $k$-cells are nonempty
Download file or watch below



• Video 10: $k$-cells are compact (in particular, closed intervals are compact)
Download file or watch below



The final main result in this section of baby Rudin, the Heine-Borel Theorem, will be proven in the beginning of the next lecture.

• Lecture Notes (static file from above videos): PDF file






Last updated: Sep 8, 2020, 12:30pm EDT