Monotone Sequence Theorem

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  • เผยแพร่เมื่อ 13 ม.ค. 2025

ความคิดเห็น • 57

  • @beatoriche7301
    @beatoriche7301 4 ปีที่แล้ว +16

    I really like your tendency to draw meaningful pictures. A common pattern of behavior I see from high school students to math majors in university is not drawing pictures, and I honestly don't understand why, since not thinking visually just makes everything so much more difficult. I've recently been reading a measure theory textbook, and a lot of the steps are quite difficult to follow on their own (some definitions in particular seem completely arbitrary), but they just pop out if you draw a nice picture. I really think it's difficult to overstate just how valuable visual intuition is when it comes to understanding abstract things; some people seem to believe being rigorous entails not thinking visually, but I really don't get this dichotomy - it's just important to keep in mind that pictures are merely aids in our thinking and that we have to make real arguments instead of just pointing at the picture.

    • @pbj4184
      @pbj4184 4 ปีที่แล้ว

      Yes while visual proofs might not be very _rigorous_ , they are very helpful for developing intuition

  • @plaustrarius
    @plaustrarius 4 ปีที่แล้ว +8

    Professor, I recently stumbled upon a sequence i find pretty cool and haven't really seen or heard anyone talk about
    en.wikipedia.org/wiki/Aronson%27s_sequence
    Aronson's sequence is an integer sequence defined by the English sentence "T is the first, fourth, eleventh, sixteenth, ... letter in this sentence."
    That's so wild to me! Hope you enjoy!
    Thank you!

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว +5

      That is really cool!!! Thanks for sharing! 😍

  • @punditgi
    @punditgi 2 ปีที่แล้ว

    An elegant explanation of an elegant theorem!

  • @tomesval
    @tomesval 4 ปีที่แล้ว +8

    Want To Find (WTF), well played Dr. Peyam...

  • @VanDerHaegenTheStampede
    @VanDerHaegenTheStampede 4 ปีที่แล้ว

    Dear Dr Peyam. The Mean Value Theorem states that if f(x) is a differentiable function, then between any two values x = a and x = b there is a value x = c such that f'(c) = average rate of change. That is, the tangent at f(c) is parallel to the line through points f(a) and f(b).
    It is worth noting that:
    i) For f(x) = x^2, c = (a + b)/2 , that is, the arithmetic mean;
    ii) For f(x) = 1/x, c = sqrt(a b) , the geometric mean;
    iii) But, for what function f(x) would c = (2 a b)/(a + b), the harmonic mean?
    I couldn't follow the book* by Sahoo and Ridel, which by the way relate f(x) = ln(x) to the identric mean, beyond other generalized means. So I humbly request your help for (iii). Thanks in advance.
    (*) "Mean Value Theorems and Functional Equations" by P. K. Sahoo, T. Riedel.

  • @lowlifeuk999
    @lowlifeuk999 4 ปีที่แล้ว

    Dr Peyam, you have done recently a lot of works on limits. I personally am very confused about hyperreal numbers and how they got postulated and more importantly why they came object of study. I personally refuse the notion of hyperreal number, but of course if serious mathematicians accept and use them, there must be something. I would be very grateful if you could shed some light on the subject. Thank you.

  • @takudzwamukura7172
    @takudzwamukura7172 3 ปีที่แล้ว

    Perfect Explanation

  • @sumitgupta6905
    @sumitgupta6905 3 ปีที่แล้ว

    just one question at 7:40 how do we ensure that s- € is in the set S of all elements of sequence? As for the definition of the sup to work the element smaller than should also belong to the set of whose sup we are considering.

    • @drpeyam
      @drpeyam  3 ปีที่แล้ว +1

      It’s not necessarily, the elements smaller do not have to be in the set

    • @sumitgupta6905
      @sumitgupta6905 3 ปีที่แล้ว

      @@drpeyam Thankyou so much for your reply sir. after watching your lecture series I have been enjoying solving the exercises.

  • @GreenMeansGOF
    @GreenMeansGOF 3 ปีที่แล้ว

    Corollary: If a_n is monotone decreasing and b_n is monotone increasing and a_n ≥ b_n, then each sequence converges.
    Proof: a_1 ≥ a_n ≥ b_n ≥ b_1 and thus each sequence is bounded and convergent.

    • @drpeyam
      @drpeyam  3 ปีที่แล้ว

      Nice

    • @GreenMeansGOF
      @GreenMeansGOF 3 ปีที่แล้ว

      @@drpeyam I learned this as I was studying a proof of Stirling’s Formula.

  • @pierreabbat6157
    @pierreabbat6157 4 ปีที่แล้ว +1

    If Modern Greek is bounded, then it converges. Ancient Greek, we're not so sure. A circumflex sequence might wander between bounds without converging.

  • @yousifkamaash5218
    @yousifkamaash5218 4 ปีที่แล้ว

    Thanks for this lecture. I have a question in geometry . What are the dimensions of an equal sides Pentagon (upside down ) inscribed inside a triangle whose sides dimensions are 77, 106, 113 . Knowing that the individual angles of Pentagon measures 108 degree and the summation of angles are 540 degrees. with my best regards .

  • @dgrandlapinblanc
    @dgrandlapinblanc 2 ปีที่แล้ว

    Ok. Thank you very much.

  • @thedoublehelix5661
    @thedoublehelix5661 4 ปีที่แล้ว

    This would also work is a(n-1)=) for all n. Also, I know you pre recorded these videos but it would be cool if you made a video proving that every sequence has a monotone subsequence. Theres a really cool proof involving peaks for that fact. Then you get Bolzano-Weierstrass theorem for free!

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว +2

      Check out the playlist

  • @adityachk2002
    @adityachk2002 4 ปีที่แล้ว +1

    Hey what happened to Steve from black pen red pen?

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      ?

    • @adityachk2002
      @adityachk2002 4 ปีที่แล้ว

      @@drpeyam he and fermatica is Friends with you and they haven't uploaded videos in a while

    • @cuonghienthaosonbuitrung2841
      @cuonghienthaosonbuitrung2841 4 ปีที่แล้ว +1

      @@adityachk2002 bprp has taken a break from youtube since he uploaded the last video

    • @adityachk2002
      @adityachk2002 4 ปีที่แล้ว +1

      cuonghienthaoson buitrung did he say that?

  • @MrCigarro50
    @MrCigarro50 4 ปีที่แล้ว

    Professor, I was given the following sequence: 1, 2, 4, 5, 8, 9, 10, 13, 16, 17, 18, 20, 21, 25, 26, 29, 32, and I was told that the next 5 points were: 33, 34, 36, 37, 40. I was unable to make sense of this. Could someone make sense of it?

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      I don’t see a pattern either, but isn’t there a website for number patterns?

  • @pbj4184
    @pbj4184 4 ปีที่แล้ว

    Dr. Peyam, you should make some fun videos once in a while as well. While Real Analysis is good, most of the time we're proving simple results which are intuitive anyway
    Love your attitude towards math 😄👍👍

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว +1

      Real analysis IS fun lol

    • @pbj4184
      @pbj4184 4 ปีที่แล้ว

      @@drpeyam Yeah but not _as_ fun as integrals 😏😏😁

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว +1

      Analysis is much better

  • @jayjayf9699
    @jayjayf9699 4 ปีที่แล้ว

    How is sn-s < epsilon ?

    • @gisopolis77
      @gisopolis77 4 ปีที่แล้ว

      It is negative and epsilon is positive

  • @vikramchoudhary2636
    @vikramchoudhary2636 3 ปีที่แล้ว

    I'm indian🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳 so this theorem is very important in bsc sem.. 2

  • @sunilkumargupta7099
    @sunilkumargupta7099 4 ปีที่แล้ว +1

    Professor...I face slightly difficulty in definite integration. Can u help me by some videos ? (Full definite integration) it will be really helpful. Love from 🇮🇳

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      Check out my integrals playlist

  • @dstigant
    @dstigant 4 ปีที่แล้ว

    DEF: Monotonic - just one fizzy drink

  • @ss-kp5ny
    @ss-kp5ny 4 ปีที่แล้ว

    Sir vedio uplode green function visualisation graphically reply

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      No thanks

    • @ss-kp5ny
      @ss-kp5ny 4 ปีที่แล้ว

      @@drpeyam
      Why

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      Because

  • @ss-kp5ny
    @ss-kp5ny 4 ปีที่แล้ว

    Fundamental greens function ∆2

  • @anirvinvaddiyar7671
    @anirvinvaddiyar7671 4 ปีที่แล้ว

    1 = sqrt(1)
    sqrt(1) = sqrt(-1 x -1)
    sqrt(-1 x -1) = sqrt(-1) x sqrt(-1)
    = i x i = -1
    1 = -1?
    line 3 is the error but can someone plz why?

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      Sqrt AB is not sqrt a x sqrt b

  • @watchaccount
    @watchaccount 4 ปีที่แล้ว

    Do you know about Aspergers' Syndrome?

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      What about it?

    • @watchaccount
      @watchaccount 4 ปีที่แล้ว

      @@drpeyam aah... Many mathematicians, programmers, geeks, etc have the same personality as people with Aspergers' Syndrome. Just wanted if you know anything about it....

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      Oh ok, I don’t know much about it

    • @watchaccount
      @watchaccount 4 ปีที่แล้ว

      @@drpeyam hmm if you find a free time try this test about Asperger's Syndrome:
      psychology-tools.com/test/autism-spectrum-quotient
      Its result may be interesting for many mathematicians..

  • @juanmanuelmillansanchez8165
    @juanmanuelmillansanchez8165 4 ปีที่แล้ว

    Dr it was an amazing proof video, but i have a question remaining if it is possible for you to answer it . ¿ How do I find the bounds ? and why should i find them to see if a sequence is convergent besides just taking the limit?.thanks for the content.

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว

      I mean the bounds depend on the problem, but usually you do |sn| and do the triangle inequality. And it’s important in practice to see if a sequence is convergent, especially for proofs

    • @juanmanuelmillansanchez8165
      @juanmanuelmillansanchez8165 4 ปีที่แล้ว

      @@drpeyam thanks a lot. About the triangle inequality, i've got one last question if you dont mind. do you know of some examples of functions that could be bounded with the triangular inequality, i googled it and i found its aplications in geometry and linear algebra but calculus.

  • @jonasdaverio9369
    @jonasdaverio9369 4 ปีที่แล้ว

    Have you already made a proof of the least upper bound property? Asking for a friend

    • @drpeyam
      @drpeyam  4 ปีที่แล้ว +1

      Yes, check out my real numbers playlist

  • @rudolfgyorkei9558
    @rudolfgyorkei9558 4 ปีที่แล้ว

    Pandemic proof channel :)

  • @karljoyeux5148
    @karljoyeux5148 4 ปีที่แล้ว +1

    M S T stands for Maladie Sexuellement Transmissible in french xD

  • @rogerkearns8094
    @rogerkearns8094 4 ปีที่แล้ว

    Plausible.