How to show a set is closed

What we need to do:

To show that the set S is closed, we need to take an arbitrary convergent sequence in S, and show that its limit belongs to S too.


What we say:

Let x_n be a sequence of elements of S which converge to a limit x_0 in S...

...and so x_0 is in S.


What we want to do:

We want to use the fact that x_n converges to x, together with additional properties of S that come from the particular problem, to show that x_0 belongs to S.


Example:

Question

Solution


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Analysis WebNotes by John Lindsay Orr.
Comments to the author: jorr@math.unl.edu

All contents copyright (C) 1995 John L. Orr
University of Nebraska--Lincoln
All rights reserved

Last modified: June 13, 1995