Thread: Help!!c problem in math

  1. #1
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    Oct 2007

    Question Help!!c problem in math

    we call s is a topology of a set S,if s is a set of several subsets of S which satisfied: 
    1.s contains  empty set and S; 
    2.if a and b belong to s ,then the intersection of a and b also belongs to s;
    3.the unity of several sets which belong to s is also belongs to s.
    assume a set S = {1,2,...,n} . How many topologies of S do we have?

  2. #2
    Woof, woof! zacs7's Avatar
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    Mar 2007
    Last edited by zacs7; 10-06-2007 at 03:07 AM. Reason: Spelt it's wrong... lol

  3. #3
    and the hat of int overfl Salem's Avatar
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    Aug 2001
    The edge of the known universe
    Nothing to do with C, just a simple visit to mathworld should suffice.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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