How to Prove Two Sets are Equal using the Method of Double Inclusion A n (A u B) = A

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  • เผยแพร่เมื่อ 17 ก.ย. 2019
  • How to Prove Two Sets are Equal using the Method of Double Inclusion A n (A u B) = A

ความคิดเห็น • 26

  • @saadafm
    @saadafm 3 ปีที่แล้ว +23

    this concept is so simple I had trouble proving it

  • @TitanTubs
    @TitanTubs ปีที่แล้ว +2

    This looks like absorption law. Can't wait to come back here in a few months to add on to this concept the teacher glossed over.

  • @poppycock3954
    @poppycock3954 3 ปีที่แล้ว +5

    Is it possible to also prove this using the Distributive law and going from there?

  • @leeming1317
    @leeming1317 ปีที่แล้ว

    Proofs clicked for me after reading Intro to Analysis by Brtle,
    I made several weak attempts at logic and sets two years ago,
    But engaging with the books definitions, then having remembered you said start with definitions,
    I did it used the definition used the math lingo, and it felt like I casted a spell,
    It was like wizzardry was guiding my pen and I knew what to write.
    Sometimes we get really excited when casting our spell and then find out IT WAS TOTALLY WRONNG.
    But that's okay! Thats part of the fun of being a sorcerer!
    Sometimes you think you extracted the annals of universe itself, only to find out its an adorable duck!
    Some say that yellow rubber duckies are all the adorable ducks from all the Math Sorcerers out there,
    We don't talk about it often because someone profited off our adorable duckies, but that neither nor their.
    P.S. Discrete Mathematics with Ducks is also a great book (hence my analogy)

  • @elsacastilloo
    @elsacastilloo 2 ปีที่แล้ว

    Would you mind doing A=B iffy A is a subset of B and B is a subset of A

  • @giftbiemba3510
    @giftbiemba3510 2 ปีที่แล้ว +1

    Life is a journey,lets soldier on till the end

  • @athyathy9433
    @athyathy9433 3 ปีที่แล้ว

    Isn't it necessary to prove for the empty sets as well in a seperate case? Since there wont be any elements and we cant show the proof by using an arbitrary element? 🙄

  • @giftbiemba3510
    @giftbiemba3510 2 ปีที่แล้ว

    Life is a journey,let's soldier on

  • @NirodhaLL
    @NirodhaLL 4 ปีที่แล้ว +7

    What other methods are there to prove equality of sets?

    • @TheMathSorcerer
      @TheMathSorcerer  4 ปีที่แล้ว +3

      sometimes you can write it differently and just do both directions at once, so really it's double inclusion but you are showing both directions at once. Let's see, here we go, an example of that: th-cam.com/video/0TgVnZCU4_w/w-d-xo.html

  • @jankubala659
    @jankubala659 3 ปีที่แล้ว +10

    Hello, I would like to ask, how does one solve these kind of problems, if the formula is not true? Our professor showed us some (this may be lost in translation) "kontra-example", which disproved the formula.

    • @TheMathSorcerer
      @TheMathSorcerer  3 ปีที่แล้ว +2

      Counter example yes, so you find one example of sets where the statement is false

    • @jankubala659
      @jankubala659 3 ปีที่แล้ว +1

      @@TheMathSorcerer Ah! A counter example! Great, finally I am able to find some results. Google only found rhymes on that word in my language :D Thank you!

    • @TheMathSorcerer
      @TheMathSorcerer  3 ปีที่แล้ว

      👍

  • @onehornstudio7152
    @onehornstudio7152 2 ปีที่แล้ว

    so nicely shown

  • @dolevmazker736
    @dolevmazker736 2 ปีที่แล้ว +1

    How do you know when to prove the proof on both sides?
    From left to right
    And from right to left
    Isnt showing one proof enough?
    How do we recognize when to do the method of double inclusion?

    • @stefanvorster4410
      @stefanvorster4410 2 ปีที่แล้ว +2

      Whenever you see a set = another set, for example A = B, then you should prove that A is a subset of B, but also B is a subset of A. Remember the definition of a subset: Let A and B be sets. If all elements in set A is in set B, then A is a subset of B. This means that B COULD still have elements that is not in A, ie. A is a proper subset of B. If A is subset of B, then it also means that B could have all the elements that A has, ie. A=B. So that is why you MUST prove that A is a subset of B, AND B is a subset of A.
      I hope this helps
      (BTW A and B I used are just placeholders)

    • @dolevmazker736
      @dolevmazker736 2 ปีที่แล้ว

      @@stefanvorster4410 thanks man, helped a lot

  • @thomashuang4931
    @thomashuang4931 3 ปีที่แล้ว

    Absorption Law ….. Done

  • @raynebenson9040
    @raynebenson9040 4 ปีที่แล้ว +18

    proofs involving sets are gross

    • @beri4138
      @beri4138 3 ปีที่แล้ว +5

      Agreed but failing the course would be more gross so I'm learning them lol

    • @raynebenson9040
      @raynebenson9040 3 ปีที่แล้ว +3

      @@beri4138 I said this when I was angry honistly they are fine

    • @beri4138
      @beri4138 3 ปีที่แล้ว

      @@raynebenson9040 You were angry because discrete math is a frustrating course. I'm currently taking it.

    • @raynebenson9040
      @raynebenson9040 3 ปีที่แล้ว +1

      @@beri4138 I was angry because proofs involving sets are difficult. I would say the majority of discreet math isn't so difficult.