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

Singleton definition from Indicator function

  1. Mar 27, 2014 #1
    The attached image is from Wikipedia under the "Singleton" article.

    What reason is the first sentence beginning "Let S be a class..." necessary to the definition?

    I am confused by the words "defined by".

    I think I understand the second sentence:

    Take the second sentence beginning "Then S is called...":
    Assume S={p,q} where p≠q, then S is not a singleton because there exists some y ϵ S for some x ϵ S such that b(p) = (p≠q). For example if y=p:
    b(p) = (p=p)
    b(p) = (p≠q) <-breaks the singleton logic
     

    Attached Files:

  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: Singleton definition from Indicator function
  1. Indicator functions (Replies: 2)

  2. Indicator function (Replies: 2)

Loading...