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Homework Help: Open sets

  1. Jan 17, 2009 #1
    1. The problem statement, all variables and given/known data

    For the following set, state and justify whether or not it is open or closed.

    2. Relevant equations

    A={z| Im z >1}

    3. The attempt at a solution

    I know the definition of an open set, but im not sure how to use it to solve this question.
  2. jcsd
  3. Jan 17, 2009 #2


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    Homework Helper

    What is you definition of open set? Do you know some examples of open sets and why they are open? This shouldn't be that challenging. It's the identical to asking if the set B of all points in the plane with coordinates (x,y) with y>1 is open.
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