1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Onto, but not one-to-one

  1. Sep 5, 2007 #1
    [SOLVED] Onto, but not one-to-one

    I need a function

    f: N -> N such that f is onto, but not one-to-one, and I can't think of one to save my life, any suggestions?
     
  2. jcsd
  3. Sep 5, 2007 #2

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    f({a,b}) = {x}.

    Sorry, you posted N to N...
     
  4. Sep 5, 2007 #3
    what does {x} stand for?
     
  5. Sep 5, 2007 #4

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    f(1) = 2
    f(x) = x for x > 1.

    Doesn't work.

    Hmm...
     
    Last edited: Sep 5, 2007
  6. Sep 5, 2007 #5
    what about

    f(1)=1
    f(2)=1
    f(n) = n-1 for n>2
     
  7. Sep 5, 2007 #6

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    I think you have just found one.
     
  8. Sep 5, 2007 #7
    k, well your original post helped me, so thank you!
     
  9. Sep 5, 2007 #8

    mathwonk

    User Avatar
    Science Advisor
    Homework Helper

    what about f(x) = 2x? no.....

    or greatest integer not greatER THan x/2, +1?

    or f(x) = x-1, for x >1 and lets see f(!) = ?

    how long did you think about this?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Onto, but not one-to-one
  1. One to one function (Replies: 1)

  2. One to one function (Replies: 1)

  3. One-to-One Function (Replies: 2)

Loading...