302.3B: Normal Subgroups

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  • Опубликовано: 20 дек 2024

Комментарии • 28

  • @fredseelig7587
    @fredseelig7587 9 лет назад +20

    I love the fact that you speak quickly. You have a very direct way of teaching, and you always keep moving. You keepp me on the edge of my seat, ready for the next reveal. Big thanks for teaching this subject clearly and free of unnecessary mathematical jargon. You realize that there are only some times when you have to invoke the heavy machinery of formal mathematics. During an initial exposure, however, you do it right: Clear, direct, and LOTS of examples and counterexamples. I have loved every one of your abstract algebra videos. Many thanks to you!

  • @facejets
    @facejets 4 года назад +2

    You're a natural at teaching this stuff. Your inflection cuts hours off of people trying to decipher what a video's writers meant by listening to an actor playing a mathematician present it. That is, if they (me) ever figure it out at all.

  • @kirstens1389
    @kirstens1389 8 лет назад +2

    Your videos are very helpful - I appreciate the fast pace and quick speaking, since my brain works fast and it helps to always stay focused on what you're saying. It helps me to get to understanding the overall point/main idea sooner, and to hear about the relationships of those ideas to other ideas. If I need something repeated then I can just replay or pause it, and the fact that everything is written on the screen allows me to take screenshots to archive that I can easily refer to later on. Your points are very succinct and somehow you end up answering all the questions I didn't know I had, since you're able to say so much in so few words :) I also appreciate the examples, and snippets of extra information you add in. Super helpful overall!

  • @jozbornn
    @jozbornn 9 лет назад +7

    Man, do I appreciate professionally-scripted, prompt review of these topics. It's a great change of pace from the hundred videos of people mumbling their way through the group axioms

  • @jessicapriscilacerqueiraba3493
    @jessicapriscilacerqueiraba3493 2 месяца назад

    awesome explanation omg thank u so much, professor

  • @WinIsGod
    @WinIsGod 11 лет назад +1

    You are an excellent teacher, thank you for these videos.

  • @余淼-e8b
    @余淼-e8b 3 года назад +2

    Prof. Salomone, your lectures are fantastic. Thanks so much for your sharing. Which text books do you recommend for your course?

  • @PunmasterSTP
    @PunmasterSTP 4 месяца назад

    Man, the insanely high quality of these videos is definitely not...normal 😃

  • @MatthewSalomone
    @MatthewSalomone  12 лет назад +4

    No, there are nonabelian groups all of whose subgroups are normal. Example: Q the quaternion group

  • @Sarah-cq5sd
    @Sarah-cq5sd 11 лет назад +1

    Thank you so much for the videos they are really helpful!

  • @hyperduality2838
    @hyperduality2838 4 месяца назад

    Left cosets are dual to right cosets synthesize normal subgroups -- the Hegelian dialectic.
    "Always two there are" -- Yoda.

  • @AnthonyCasadonte
    @AnthonyCasadonte 12 лет назад

    Ahhh interesting thought here in rewatching this video: firstly suppose we express something like a topological space but with groups in the form of a group's underlying set S and the group structure G together as (S, G) where G contains elements in S such that two elements are related by a binary operation (related in the sense of a relation that is associated) and such a xRb=c where a, b, and c are in S. And all the other aspects of a group are there. We can also consider for a set its normal

  • @wangderek2324
    @wangderek2324 10 лет назад

    simple and clear !

  • @AnthonyCasadonte
    @AnthonyCasadonte 12 лет назад +1

    ...subgroups, for example such a one H, as (S,H). But if G is simple I thought this is kind of like the trivial topology! Is there a name for a group with all of its subgroups being normal subgroups? (by this analogy would be perhaps like the discrete topology) Just a crazy thought hahaha

  • @ninosawbrzostowiecki1892
    @ninosawbrzostowiecki1892 9 лет назад +3

    Dude, I bet you're 28. Only a 28 year old could be this awesome!

    • @MatthewSalomone
      @MatthewSalomone  9 лет назад +13

      I used to be 28. And, 28 is a triangular number. Does that count?

  • @vullnetlepaja259
    @vullnetlepaja259 11 лет назад +1

    how to find subgroups of D4?

  • @noorameera26
    @noorameera26 7 лет назад

    At 3:41 how did you get (34)(14) = (143) ?

    • @chriswaggoner4691
      @chriswaggoner4691 7 лет назад

      ABCD swap 1&4 = DBCA
      DBCA swap 3&4 = DBAC
      ABCD (A -> D -> C -> A) = DBAC

    • @chriswaggoner4691
      @chriswaggoner4691 7 лет назад +1

      (remember these functions compose in the Arabic / Hebrew reading direction, not the English / French reading direction)

    • @beback_
      @beback_ 7 лет назад

      I think it helps to view permutations of size 2 as simple transpositions. Looking at it that way, first swap the first and the forth, then swap the forth (previous first) and the third (which didn't change under the previous transposition).

  • @GopinathShanmugam
    @GopinathShanmugam 5 лет назад

    Hello Sir :-)
    In group theory Normalizer and normal subgroup both are same?

  • @AnthonyCasadonte
    @AnthonyCasadonte 12 лет назад +1

    Well any abelian group has only normal subgroups...hmmm does a group have to be abelian for all of its subgroups to be normal?

  •  7 лет назад

    how did you get (13)(12)(34) ? You didnt wait . You wrote an answer without waiting. How did you do it quickly ? How did you do it? What is the practical way?

  • @kiruthigas6346
    @kiruthigas6346 6 лет назад

    very useful

  • @fazedRR
    @fazedRR 11 лет назад

    your explanations are so nicely expressed that it's a shame you speak so quickly!