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Graph Theory Help!

  1. Aug 2, 2011 #1
    z = positive int, Y = {1 2 3 ..... n} where Y = n greater or equal to z
    defines Gzn

    1)work out a formula in n and z for the edges in G zn, the vertex set to include all possible z elements subsets of Y

    help please whats the formula?
    i know how to work out the number of vertices in a formula
    which is n!/z!(n-z)!
    been stuck on the formula for the edges for ages... i also know how to calculate the edges if its a complete graph e.g. G1n is n(n-1)/2 since degree (v)= doubles the edges

    e.g. G23 has 3 vertexs of {12}{13}{23} no edges
    Last edited: Aug 2, 2011
  2. jcsd
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