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Example of dense non surjective operator

  1. May 25, 2009 #1
    Hi, can anyone give me an example of a bounded operator on a Hilbert space that has dense range but is not surjective? (Preferably on a separable Hilbert space)

    Im pretty sure such an operator exists since the open mapping theorem requires surjectivity and not just dense range, but its just bothering me that I can't find an example.
  2. jcsd
  3. Feb 9, 2011 #2
    How about \ell_1 (all absolutely summable sequences) being mapped into L_2[0, 2\pi) ( all complex valued square integrable functions on [0, 2\pi) ) by

    (a_n) -> \sum a_n \exp( \sqrt{-1} n x)
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