Notation question

  • Thread starter Asphodel
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  • #1
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I have something like this:

[tex]\bigcup^{N}_{1}x_{n}[/tex]

What am I looking at? Is this [tex]x_{1}\cup x_{2}\cup x_{3}\cup ...\cup x_{N}[/tex]?
 
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Answers and Replies

  • #2
Ben Niehoff
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Yes, it's a union over some collection of sets.
 
  • #3
JasonRox
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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.
 
  • #4
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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.
 

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