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Math Help - open and closed

  1. #1
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    open and closed

    consider (ℝ,τ) , where τ={∅}∪{u⊆ℝ:{-π,π}⊆u}.
    Is [-4.4] open in (ℝ,τ) ? Justify your answer
    Is (-3,3) closed in (ℝ,τ) ? Justify your answer
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  2. #2
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by blbl View Post
    consider (ℝ,τ) , where τ={∅}∪{u⊆ℝ:{-π,π}⊆u}.
    Is [-4.4] open in (ℝ,τ) ? Justify your answer
    Is (-3,3) closed in (ℝ,τ) ? Justify your answer
    This is starting to get ridiculous. What do you think??? You still haven't responded as to what you really mean by this specific topology!
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