Identifying Open, Closed, and Compact Sets | Real Analysis Exercises

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We look at six sets and determine if each one is either open, closed, compact, or any combination of the three. We will use multiple definitions in our solutions. An open set is a set whose elements all have some neighborhood around them completely contained in the set. A closed set is a complement of an open set, or equivalently a set whose limit points are all contained in the set. A compact set is closed and bounded, or equivalently a set whose open covers all have finite subcovers. #realanalysis

Thanks Summatin for the chapters!
0:00 Intro
0:20 Integers
2:07 Union of reciprocals of natural numbers with set containing zero
3:20 Real numbers
4:05 Union of open and closed intervals
5:01 Rational numbers
5:42 Singleton set containing only seven
6:23 Real numbers revisited

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Love the channel! One quick correction: 7 is not a limit point of {7}, at least according to the definition given in Understanding Analysis.

curiouslockpicker
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I'm studying point set topology and hadn't been taught compactness in real analysis before (since it's covered in topology as an optional module) and I really struggled getting to grasps with it. its nice to see you go through plenty of examples in the euclidean topology that can act as a referral point. So thank you!

samuelhawksworth
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nailed 5, maybe more of these? These kinds of examples are really indispensable. Thanks a ton

soumyadipghosh
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0:20: Integers
2:07: Union of reciprocals of natural numbers with set containing zero
3:20: Real numbers
4:05: Union of open and closed intervals
5:01: Rational numbers
5:42: Singleton set containing only seven
6:23: Real numbers (again)

summatim
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Nice examples and discussions of reasons.

TranquilSeaOfMath
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Hey, love the examples!! Just wanted to ask where is the video that explains that a set is compact if it is closed and bounded?

okikiolaotitoloju