Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Notation question

  1. Nov 12, 2007 #1
    I have something like this:


    What am I looking at? Is this [tex]x_{1}\cup x_{2}\cup x_{3}\cup ...\cup x_{N}[/tex]?
    Last edited: Nov 12, 2007
  2. jcsd
  3. Nov 12, 2007 #2

    Ben Niehoff

    User Avatar
    Science Advisor
    Gold Member

    Yes, it's a union over some collection of sets.
  4. Nov 12, 2007 #3


    User Avatar
    Homework Helper
    Gold Member

    Not necessarily because N can be infinite say...

    x1 U x2 U x3 U ...

    But also, N can be uncountable, which means listing them in whatever way is pointless and incorrect.
  5. Nov 12, 2007 #4
    Thanks, Folland started using it without prior explanation (that I noticed).

    It's the only interpretation that I could think of that made sense, but I didn't want to guess since it's already part of one theorem and one definition and if I guessed wrong then everything I did using those could be thrown off.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Notation question
  1. Notation question (Replies: 1)

  2. Notation question (Replies: 2)

  3. Notation question. (Replies: 2)

  4. Question on notation (Replies: 5)

  5. Notation question (Replies: 4)