301.5G Transpositions and the Alternating Group

Поділитися
Вставка
  • Опубліковано 23 гру 2024

КОМЕНТАРІ • 14

  • @gaaraofddarkness
    @gaaraofddarkness 4 роки тому +2

    Hello sir I dont follow the proof of An being a Subgroup of Sn fully... What if there is a transposition which is common to both σ and τ?

    • @MatthewSalomone
      @MatthewSalomone  4 роки тому +1

      Then there would be a pair (an even number!) of that transposition, and even if στ were rearranged so as to cancel that transposition, the total # of transpositions would still be even for that reason. So the best answer is (though I didn't prove it here): The sign of a permutation is *independent* of which product of transpositions we choose to express it.

  • @choopa_noopa
    @choopa_noopa 2 роки тому +1

    for the subroup test... Say we swap sigma and tao to a and b respectively. Are you not instead supposed to show that not a,b exist in A_n but also ab^(-1) exists in A_n?

    • @kmn1794
      @kmn1794 Рік тому +1

      A permutation and its inverse have the same parity and so if the alternating group of a symmetric group is all permutations having even parity then it must also include all the inverses.

    • @PunmasterSTP
      @PunmasterSTP 4 місяці тому

      I think you're thinking of the *one-step* subgroup test. There's also the *two-step* subgroup test and the *finite* subgroup test.
      ua-cam.com/video/9kQw4tY-z1I/v-deo.htmlfeature=shared

  • @PunmasterSTP
    @PunmasterSTP 4 місяці тому

    Q: What's green and sings?
    A: Elvis Parsley!
    (I still remember that was posted somewhere in my elementary school)

  • @normmacdonaldfan
    @normmacdonaldfan 3 роки тому +1

    Absolute GEM

  • @rosannaa.daitao3764
    @rosannaa.daitao3764 4 роки тому +2

    This is great! Thanks a lot...

  • @ponyboy4416
    @ponyboy4416 4 роки тому +2

    I like this and am so glad it exists. Sub.

  • @mateusbalotin7247
    @mateusbalotin7247 2 роки тому +1

    Hey, aren't you the dude singing that group song hahaha. Thank you for the class!! Exactly what I was looking for. Hope you have an amazing week!!!😁

    • @MatthewSalomone
      @MatthewSalomone  2 роки тому +1

      You are correct good sir 😇

    • @PunmasterSTP
      @PunmasterSTP 4 місяці тому

      Yeah that song was awesome, and it was fun to just stumble across that while going through his group theory playlist 😆

  • @keldonchase4492
    @keldonchase4492 Рік тому

    I’m sorry but I think
    (26745)=(25)(24)(27)(26).
    I think you have it backwards.

    • @PunmasterSTP
      @PunmasterSTP 4 місяці тому

      I think Professor Salomone is correct that (26745) = (26)(27)(24)(25). At 3:37 he says he's using the formalism where he's reading the transpositions from left to right, and working it out on paper that's what I get too.