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Aleph null problem.

  1. Dec 11, 2006 #1
    i have a function f:A->B, im also given that |B|<=null aleph, and for every b in B, |f^-1({b})|<=null aleph, i need to prove that |A|<=null aleph.
    basically i think that A equals the union of f^-1({b}) for every b in B, and by another theorem i can consequently assert that |A|<=null aleph.

    but is this correct?
  2. jcsd
  3. Dec 11, 2006 #2


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  4. Dec 11, 2006 #3
    AKG, thanks.
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