jHan
jHan
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How to Construct Infinite Sets
What are the natural numbers? The integers? The rationals? The reals? While we may have an intuitive understanding of these numbers and sets, it is not so easy to actually construct these sets formally. To do so, we must use some axioms of set theory, and using only these assumptions, formally describe what these infinite sets should look like. We will develop various tools in set theory, like ordered pairs, relations, ordering, and equivalence classes, to begin with only zero, and from nothing, build all of the real numbers.
0:00 Introduction
1:46 Set Theory and Basic Notions
8:13 Axiom of Infinity and the Naturals
13:09 The Integers
23:19 The Rationals
26:00 The Reals
36:38 Conclusion
Additional Resources:
Wikipedia article on the Construction of the naturals: en.wikipedia.org/w/index.php?title=Natural_number#Set-theoretic_definition
Wikipedia article on the Construction of the Reals: en.wikipedia.org/wiki/Construction_of_the_real_numbers
Wikipedia article on ZFC: en.wikipedia.org/wiki/Zermelo-Fraenkel_set_theory
Axiom of Choice video: th-cam.com/video/szfsGJ_PGQ0/w-d-xo.html
Cardinality of the Continuum video: th-cam.com/video/iaUwNuaSLUk/w-d-xo.html
Music:
c418.bandcamp.com/album/dief
Imaginary Interlude by C418
c418.bandcamp.com/album/circle
minimal by C418
love by C418
patriciataxxon.bandcamp.com/album/crocus
Crocus 2 by Patricia Taxxon
Far the Days Come by Letter Box
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Animations were made by Manim, an open-source python-based animation program by 3Blue1Brown.
github.com/3b1b/manim
This video was submitted to 3Blue1Brown's SoMEπ (Summer of Math Exposition Community Edition).
some.3b1b.co/
มุมมอง: 5 814

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ความคิดเห็น

  • @AdinaStama7
    @AdinaStama7 12 ชั่วโมงที่ผ่านมา

    The comtinuum is 1. A single unit. 1 + 1 + 1 + 1 + 1... = 1 = N = R. Numbers have relative values, they are ratios of an single unit. 1 + 1 + 1 + 1 = 4. Each 1 have a value of 1/4, 1 € N. N = R = C in 1. This because every real number can be expressed as an inverse of 1 times an multiple of 1. 0.5 x 2= 1, 0.25 x 4= 1. Every number can be expresed as an ratio of 1. That means 2 is 2/1 when the value of the 2 individual units is 1/2. Natural and real numbers have relative values. Numbers come from a single UNIT.

  • @harley6659
    @harley6659 2 วันที่ผ่านมา

    The cyclical nature of these functions is beautiful. If you’ve ever done an integration by parts problem with a trig function it’ll start to cycle if you don’t stop it early. Also the way I remember derivatives and integrals of sin and cos is with four quadrants. sin -cos cos -sin If you move clockwise on the wheel it gives you the derivative. If you move counterclockwise, the integral

  • @johnchessant3012
    @johnchessant3012 3 วันที่ผ่านมา

    Awesome video!

  • @chessematics
    @chessematics 5 วันที่ผ่านมา

    Amazing video on the topic.

  • @vibhupandya6103
    @vibhupandya6103 6 วันที่ผ่านมา

    Mmmrrmm yesss the nOnEmPtY set has eLeMeNtS that i can pick!!

  • @sirousmohseni4
    @sirousmohseni4 7 วันที่ผ่านมา

    You are doing a great job unpacking so much in this video. I need to watch it again to absorb more if it.

  • @etramulnn785
    @etramulnn785 13 วันที่ผ่านมา

    big W for your vid and yt career, you remind me of vsause but more formal but still introductionary like him, im studying math rn and this vid is actually good quality

  • @whyre69
    @whyre69 13 วันที่ผ่านมา

    that's amazing

  • @rossholst5315
    @rossholst5315 14 วันที่ผ่านมา

    The problem I have with the diagonal method is that the same method can be used to show any partial set of whole numbers is incomplete.

  • @tanveerwani9617
    @tanveerwani9617 14 วันที่ผ่านมา

    Zorns Lemma

  • @jpphoton
    @jpphoton 15 วันที่ผ่านมา

    Excellent breakdown and video here. also/and the outro commentary of these concepts - master class. ty

  • @kpk1171
    @kpk1171 16 วันที่ผ่านมา

    This video was amazing!

  • @ZeubZebi-f6i
    @ZeubZebi-f6i 19 วันที่ผ่านมา

    realy good vidéo, thank you

  • @Flappyjack-h4f
    @Flappyjack-h4f 20 วันที่ผ่านมา

    We would like to know more about Yutaka Taniyama

  • @mehdizangiabadi-iw6tn
    @mehdizangiabadi-iw6tn 28 วันที่ผ่านมา

    means e^-1 =-1 is wrong and π must=0

  • @mehdizangiabadi-iw6tn
    @mehdizangiabadi-iw6tn 29 วันที่ผ่านมา

    How many degrees is X?🤔

  • @mehdizangiabadi-iw6tn
    @mehdizangiabadi-iw6tn หลายเดือนก่อน

    0=(0,0)

  • @mehdizangiabadi-iw6tn
    @mehdizangiabadi-iw6tn หลายเดือนก่อน

    cos(0)+isin(0)=0 but it isn't equal really 0

  • @dng88
    @dng88 หลายเดือนก่อน

    Background noise (drum) is very annoying.

  • @norbi8072
    @norbi8072 หลายเดือนก่อน

    That was magical...simple and elegant!

  • @СергейЖданов-э5р
    @СергейЖданов-э5р หลายเดือนก่อน

    Music on the background is very disturbing

  • @deleted-something
    @deleted-something หลายเดือนก่อน

    an axiom that does crazy stuff

  • @blackestbill7454
    @blackestbill7454 หลายเดือนก่อน

    Euler and Guass were the greatest mathematicians to ever live respective to their time

  • @IsaacChristopher-z8w
    @IsaacChristopher-z8w หลายเดือนก่อน

    Thank you for this video! I understand the AoC much better after watching it. It's fascinating to see how thoroughly set theory is connected with other branches of mathematics. The visuals and audio were fantastic, and you explained things at exactly the right level for me (2nd year undergrad). I feel like I've just watched a very strong lecture at my university. Subscribed :)

  • @birdy_
    @birdy_ หลายเดือนก่อน

    4:22 Bernays

  • @eunchanhyung6947
    @eunchanhyung6947 หลายเดือนก่อน

    talk tuah

  • @eunchanhyung6947
    @eunchanhyung6947 หลายเดือนก่อน

    poopy fart head

  • @thelifeofibo
    @thelifeofibo หลายเดือนก่อน

    i spent a day trying to prove this with the taylor series, still my most enjoyable day in terms of math

  • @neutralzone7775
    @neutralzone7775 หลายเดือนก่อน

    Amazing video, Physics major and we use this all the time, now I have a much more intuitive understanding of the Euler's formula

  • @Zack-mp6ys
    @Zack-mp6ys หลายเดือนก่อน

    I am familiar with Dedekind Cut a few years back. But this is the first time I learned the rationale behind the rationals.

  • @Zack-mp6ys
    @Zack-mp6ys หลายเดือนก่อน

    A whole series of videos of ZFC like this will surely go viral.

  • @AA-100
    @AA-100 2 หลายเดือนก่อน

    2^136279841-1, new largest known prime, discovered Oct 12 2024

  • @tommyrjensen
    @tommyrjensen 2 หลายเดือนก่อน

    In a university study you would expect a more precise language. You would hear Euclid's proof explained as "there are infinitely many primes", as in, not just finitely many primes. Rather than "there is an infinite number of primes", easily misunderstood as if to say there is a certain number of primes, and that number is infinite. This only becomes meaningful once you also realize that there is a set the elements of which are exactly the primes, and this set has a certain cardinality, and that cardinality is infinite.

  • @c3pheiplay
    @c3pheiplay 2 หลายเดือนก่อน

    Thanks! This really helped

  • @RandomLyricsGuy-y5r
    @RandomLyricsGuy-y5r 2 หลายเดือนก่อน

    im gonna try and find the biggest perfect number i can fathom Day 1: 137438691328

  • @Founder2721
    @Founder2721 2 หลายเดือนก่อน

    I started gasping and lighting screaming when i saw the end of the taylor series proof. Im bewildered

    • @pelasgeuspelasgeus4634
      @pelasgeuspelasgeus4634 2 หลายเดือนก่อน

      That proof is wrong. Taylor series are valid for real integers, not marvel universe numbers like i*x.

    • @Founder2721
      @Founder2721 2 หลายเดือนก่อน

      @pelasgeuspelasgeus4634 *bigger gasp*

    • @pelasgeuspelasgeus4634
      @pelasgeuspelasgeus4634 2 หลายเดือนก่อน

      @@Founder2721 meaning?

  • @Founder2721
    @Founder2721 2 หลายเดือนก่อน

    I love this

  • @jacobg1219
    @jacobg1219 2 หลายเดือนก่อน

    Great video, it's so hard to find maths content that isnt either not related to what you want to find or just incredibly complicated.

  • @pelasgeuspelasgeus4634
    @pelasgeuspelasgeus4634 2 หลายเดือนก่อน

    This video is pointless since euler formula is simply wrong. Left side is exp function which ranges from 1 to infinity. Right side is the sum of 2 trig functions each ranging from -1 to 1. So, how can these sides ever be equal? Stop parotting, start thinking.

  • @fahriz9163
    @fahriz9163 2 หลายเดือนก่อน

    what's your book there?

  • @Soumyadip.B07
    @Soumyadip.B07 2 หลายเดือนก่อน

    You deserve more subscribers, amazing explanation loved it.

  • @Киноварь
    @Киноварь 2 หลายเดือนก่อน

    The game.

  • @ketaksingh5465
    @ketaksingh5465 2 หลายเดือนก่อน

    amazing man! subscribed

  • @williamnathanael412
    @williamnathanael412 2 หลายเดือนก่อน

    22:50 I almost immediately think, why can't the reals be ordered like you do with the integers? Compare the absolutes of two numbers, and give the priority to the positive should their absolutes be equal. Unless of course, you are talking about Dedekind cuts.

    • @MikeRosoftJH
      @MikeRosoftJH หลายเดือนก่อน

      Okay, surely you can do that; but that's not a well-ordering relation, because not every set has a minimum. Consider an open interval from 0 to 1; it can be seen that re-ordering negative numbers doesn't change anything. What's the minimum of this set? 1/10? But 1/100 is closer to zero. 1/1000 is even closer. And so on; for any positive number x there is one closer to zero, such as x/2. The infimum of this set is of course 0 (any set bounded from below has one); but that's not a minimum because it's not an element of the open interval. In fact, a well-ordering relation on real numbers can't be constructed in the usual sense; no formula can be proven to define one (in the sense that there exists exactly one set satisfying that formula and that set is a well-ordering of real numbers). The existence of such a well-ordering is a consequence of axiom of choice; without axiom of choice it's consistent that real numbers can't be well-ordered.

  • @aphschl4347
    @aphschl4347 2 หลายเดือนก่อน

    Thanks for the video really helpful for my university class.

  • @ZimingWang-cl7nb
    @ZimingWang-cl7nb 2 หลายเดือนก่อน

    This is a perfect video! I just have one question: why is natural number to the power of natural number the set of all positive integer functions? Can someone please explain it for me😢

  • @HousmanNat-z8r
    @HousmanNat-z8r 2 หลายเดือนก่อน

    Ratke Spurs

  • @pictureking1958
    @pictureking1958 3 หลายเดือนก่อน

    Amazing video but I still have one question. Like how do you classify e^ix as imaginary or real? Like for imaginary i must be multiplied to the number and for real no i at all. But this e^ix has i in the exponent, so I got confused at this part.

    • @pelasgeuspelasgeus4634
      @pelasgeuspelasgeus4634 หลายเดือนก่อน

      Is that the only thing confusing you? How about the fact that one side (exp function) goes from 1 to inf while the other side (sum of 2 trig functions) is obviously finite? How can they be equal?

  • @rambleitch
    @rambleitch 3 หลายเดือนก่อน

    14:46 wouldn't the domain be a subset of the power set of X? if x belongs to a particular Xy_1 it cant belong to any other such Xy_2 so the domain would be like disjoint subsets of X?

  • @marcoottina654
    @marcoottina654 3 หลายเดือนก่อน

    17:00 The musical choice is fantastic! It truly whisper the idea of "there's some powerful concept here to be grasped, but it's doomed indeed". Genius! Also, the part immediately preceding it has got a VERY inspiring music, which lift the spirit to the idea of "this concept is very powerful, harnessing the power and patience of infinity to gain the ability to be exact"! (17:00 _unless_ ... *there's a hole** ) also, the ending speech and the "almost pun" is ... delightful! I love it!