1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is this nonsense? Notation type of quesiton

  1. Aug 25, 2013 #1
    1. The problem statement, all variables and given/known data

    Hi All,
    I was trying to write that ## I ## is unique. ##I ## is my identity element.

    2. Relevant equations



    3. The attempt at a solution

    Maybe I can write

    ## \exists I | I = I ##
    ##\forall I \in G ##
    Except with spaces. Is this not a way?


    Just trying to specify that this thing is unique.
     
  2. jcsd
  3. Aug 25, 2013 #2

    lurflurf

    User Avatar
    Homework Helper

  4. Aug 25, 2013 #3
    Could you say that and then just start with this assumption I = I and proceed with a proof from there?Thanks
     
  5. Aug 25, 2013 #4

    lurflurf

    User Avatar
    Homework Helper

    What does I=I mean? It is always true. You want to say something like there exist a unique identity or if I and I' are any two identities then I=I'.
     
  6. Aug 25, 2013 #5
    The question tells "Given there exits a unique identity element." So I'm just trying to use this. But having a hard time saying what I want. What I was trying to say before this was ##\exists ! I ## such that I = I.
    But I guess....not sure how I'm trying to say this.
     
  7. Aug 25, 2013 #6

    lurflurf

    User Avatar
    Homework Helper

    I would say something like
    $$\exists ! I \in G |(xI=Ix=x) \forall x \in G$$
    or
    $$(xy=yx=x) \forall x \in G \implies y=I$$
     
  8. Aug 25, 2013 #7

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    "I= I" is always true whether I is denoting something that is "unique" or not. For example [itex]\frac{1}{2}= \frac{1}{2}[/itex] even though [itex]\frac{1}{2}= \frac{2}{4}[/itex] as well.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Is this nonsense? Notation type of quesiton
  1. Probability Quesiton (Replies: 1)

  2. Vector notation (Replies: 2)

  3. Sigma notation (Replies: 3)

  4. Help with notation (Replies: 8)

Loading...