Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Lets say you have a set S = {1, 2, 3}

  1. Jul 20, 2011 #1
    Lets say you have a set S = {1, 2, 3}

    The subsets would be the following:
    {} (nullset)
    {1}, {2,}, {3}
    {1, 2}, {2, 3}, {1, 3}
    {1, 2, 3}

    Would {1, 2} be considered the same subset as {2, 1}?
     
  2. jcsd
  3. Jul 20, 2011 #2
    Re: Subsets

    yes - the set {1, 2} is equal to {2, 1}.
     
  4. Jul 20, 2011 #3
    Re: Subsets

    You can verify that they are the same set (prove is such a formal word...)
    Since the power set of S is the set set of all subsets of S, and the power set has 2^n elements, (n being the number of elements in S), you know you should have 8 subsets in this example. If {1,2} is a different set than {2,1}, you'd have more sets than allowed, so they must be the same.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook