Open Covers, Finite Subcovers, and Compact Sets | Real Analysis

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  • Опубліковано 17 січ 2025

КОМЕНТАРІ • 65

  • @lizzywhite4231
    @lizzywhite4231 Рік тому +56

    Please please keep making these! The number of creators who make quality undergrad maths content is VERY VERY small. Your videos have been so helpful for my first year :)

  • @austinhendrix6117
    @austinhendrix6117 3 місяці тому +4

    Taking Analysis for the first time and I am not understanding it too well. I also work a full-time job and 2 part time jobs, so I don't have too much time to study. Your video has helped me grasp it in such a way I feel more comfortable working on some proofs! Thank you!

    • @WrathofMath
      @WrathofMath  3 місяці тому

      Glad to help! Good luck with your busy schedule and the class, let me know if you ever have any questions!

    • @robg4472
      @robg4472 2 місяці тому

      Replace '1 full time job and 2 part time jobs' with 'one full time job and 2 young childre'n and this sounds like my story. Not too many of us taking online Real Analysis - which school do you go to ?

  • @swoyer2
    @swoyer2 Рік тому +18

    This is a great video, sucks that higher level math doesn't do well on youtube. Thank you

    • @robg4472
      @robg4472 2 місяці тому +1

      Isn't it crazy that you can create content complaining about one boogey man or another and become a multi-millionaire on you tube and yet most of the creators of more serious intellectual content can't make a living doing it.

  • @JesseReed-n9o
    @JesseReed-n9o 10 місяців тому +1

    Taking my first real analysis class and this video really helped with understanding covers! Thank you so much.

    • @WrathofMath
      @WrathofMath  10 місяців тому

      Glad it helped - best of luck!

  • @KhaznahAlkhaldi
    @KhaznahAlkhaldi 4 місяці тому

    Your videos really help me understand a compact set and open cover.
    Thank you

    • @WrathofMath
      @WrathofMath  4 місяці тому +1

      Glad to help, thanks for watching!

  • @jayantsoni22488
    @jayantsoni22488 Рік тому +2

    You really explain very well. Thanks a lot.

  • @begum9591
    @begum9591 Рік тому

    Thank you for the quality content! Im loving these Real Analysis videos.❤

    • @WrathofMath
      @WrathofMath  Рік тому

      Thank you for watching! More real analysis videos to come this summer, I find they take the longest to make!

  • @denuwanvlog
    @denuwanvlog 10 днів тому

    Thanks for this ❤️

  • @kikiapeach
    @kikiapeach Рік тому +1

    so clear and helpful!!

  • @ashleyjuarez9563
    @ashleyjuarez9563 Рік тому +5

    can you also go over the Heine-Borel Theorem? love how you explain things

    • @WrathofMath
      @WrathofMath  Рік тому +1

      I certainly will! Which equivalence are you looking for, the open cover definition of compact sets and closed/boundedness?

    • @ashleyjuarez9563
      @ashleyjuarez9563 Рік тому

      yeah and also, K is closed/bounded and every open cover for K has a finite subcover

    • @thomasjefferson6225
      @thomasjefferson6225 Рік тому +1

      ​​@@WrathofMath please make it before my exam in may plz, open covering!!!!!

  • @zakhelexulu3394
    @zakhelexulu3394 8 місяців тому

    Thank you so much , you make everything easy.

    • @WrathofMath
      @WrathofMath  8 місяців тому

      Glad to help, thanks for watching!

  • @chilledorda
    @chilledorda Рік тому

    It is really helpful! Thank you!

  • @ariwang8613
    @ariwang8613 7 місяців тому

    Amazing video

  • @Bruh-pl5oe
    @Bruh-pl5oe Рік тому

    Really helpful ❤️

  • @sylvieliu6366
    @sylvieliu6366 Рік тому

    Thank you! You saved my life

    • @WrathofMath
      @WrathofMath  Рік тому

      It is my duty! Thanks for watching!

  • @shyamdas6231
    @shyamdas6231 Рік тому

    Thank you so much,Sir!

  • @EmilyYebananapie
    @EmilyYebananapie Рік тому

    So helpful thank you!!

    • @WrathofMath
      @WrathofMath  Рік тому

      Glad to help - thanks for watching!

  • @punditgi
    @punditgi Рік тому +1

    Wrath of Math hits the nitty-gritty. Awesome! 😃

    • @WrathofMath
      @WrathofMath  Рік тому +4

      Can't wait for 1000 videos from now when my Real Analysis playlist is done!

  • @henrywoo1668
    @henrywoo1668 Рік тому

    Thank you for your great video ❤

  • @hemant5744
    @hemant5744 9 місяців тому

    THANKS THIS HELPED ME

    • @WrathofMath
      @WrathofMath  9 місяців тому +1

      Glad to hear it, thanks for watching!

  • @Dupamine
    @Dupamine 7 місяців тому

    Do you have something on heine boral theorem ?

  • @JRTO_X
    @JRTO_X 6 місяців тому

    At 8:48 are you saying that the first example (0,2) : {(1/k, 2-1/k)} will not have a finite subcover because if we restrict the indexing set of k from 1 to infinity then it will always be impossible for that set to be able to cover (0,2). If other words k must go from 0 to infinity for {(1/k, 2-1/k)} to cover (0,2)? Is that line of thinking correct? Many thanks for all the Real Analysis videos, you have been a great help with my degree 😄

  • @AmanAman-p7p3b
    @AmanAman-p7p3b Рік тому

    Thanku for this genius explanation

    • @WrathofMath
      @WrathofMath  Рік тому

      I do my best, thanks for watching!

  • @jessicapriscilacerqueiraba3493
    @jessicapriscilacerqueiraba3493 3 місяці тому

    continue de playlist plssss i wanna know more about compact sets

  • @wqr0805
    @wqr0805 Рік тому +2

    I really appreciate your videos. This real analysis series with the book I'm reading by Jay Cummings is of a great match!please up load more!!!!

    • @WrathofMath
      @WrathofMath  Рік тому

      So glad they've been helpful - thanks for watching! My playlist is mostly based on Jay's book and the Stephen Abbott text - at least so far, so it's definitely a good match! I intend on making many more this summer. Also, Jay Cummings appeared in my TI-108 documentary, if you're curious and have an hour+ to spare: ua-cam.com/video/xrmqoKchspo/v-deo.html&pp=ygUFdGkxMDg%3D

  • @tishloves
    @tishloves Місяць тому

    hey unrelated to the video but which note taking app do you use? it looks really cool

    • @WrathofMath
      @WrathofMath  Місяць тому

      Notability for iPad Pro! It's a great app, though the developers insist on regularly updating it to make it worse.

  • @okikiolaotitoloju2208
    @okikiolaotitoloju2208 Рік тому

    Hey, I have a question
    At 10:20 You said wasn't (-2,1) compact because every one of its open covers did not have a finite subcover, So what is "every open cover" in that example and how do they not contain finite subcovers?

    • @WrathofMath
      @WrathofMath  Рік тому +1

      In that example we looked at one open cover which happened to have a finite subcover. We did not establish anything about "all open covers" of (-2,1) which would be necessary to establish compactness. I don't explicitly show you an open cover without a finite subcover because the previous example showed how an an open cover of an open interval could be constructed so that it has no finite subcovers, showing open intervals are not compact.

    • @matsobanemarksmokhudu2584
      @matsobanemarksmokhudu2584 Рік тому

      @@WrathofMath just explain why it makes that cover not compact because i still dont get why its not compact

    • @Kantoot161
      @Kantoot161 Рік тому

      @@matsobanemarksmokhudu2584 It's not compact because it didnt satisfy the definition. The definition states an "if and only if" and so he used the first example to prove it's not compact

  • @kanishkamudgal5103
    @kanishkamudgal5103 10 місяців тому

    Brooooooooo.u justttnailedddd ittt

  • @toptom5325
    @toptom5325 9 місяців тому

    legend

  • @Түмэн-АмгаланАлимаа
    @Түмэн-АмгаланАлимаа 10 місяців тому

    Hello, thank you very much for making the video, it helped me a lot. And please excuse my not good english. And i have a question on the third example that is about open cover of [0,2]. You wrote union between two sets and i think then it would make it (-0.1, 2.4) which is not family of sets, then i think it can't be the cover. But if you write it differently like {"the family of sets", (-0.1, 0.1), (1.8, 2.4)} then i think it can be a cover of [0,2]. (but i am not that sure of it and if i am wrong please correct me, thank you)

  • @bobb0008
    @bobb0008 2 дні тому

    why [ (-infinity,0) , (-1,0.5) , (0.1,9) ], is not compact ?
    it has -2 and 1 in the subsets.

  • @FlexThoseMuscles
    @FlexThoseMuscles 11 місяців тому

    interesting video. not monotonous. I understand hurray!!

    • @WrathofMath
      @WrathofMath  11 місяців тому +1

      Awesome - thanks for watching!

  • @alondrachavez1234
    @alondrachavez1234 Рік тому

    What literature would you recommend as an alternative for this video? [I learn better from reading than watching videos.]

  • @sanjursan
    @sanjursan Рік тому

    You say "any index set" but it seems only countable sets are used. What would happen if we specified a, say subset of the reals as the index set. Take the unit interval of R as the index for example. What then? (No this is not any homework problem.)

  • @coreymonsta7505
    @coreymonsta7505 Рік тому

    Painful to listen to without turning the volume down lol

    • @WrathofMath
      @WrathofMath  Рік тому +3

      I try to make the volume loud and clear so anyone on a phone can hear easily. I notice on my phone sometimes the videos are a little hard to hear even on max volume. But I know I’ve gone overboard a couple of times haha, I hope the video was helpful otherwise.

    • @coreymonsta7505
      @coreymonsta7505 Рік тому

      @@WrathofMath I already passed analysis qual it’s fine lol

    • @cyrenux
      @cyrenux Рік тому

      ​@@WrathofMaththat is the case for me as well, there are times where i can barely hear anything despite the volume being on max, thanks for being that considerate