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!

Discrete Math: Self-referential formula

  1. Nov 20, 2011 #1
    1. The problem statement, all variables and given/known data

    Figure out a self-referential formula for the number of handshakes required for a group of n aliens to introduce themselves by hand-calculating a few small values and coming up with a solution.

    2. Relevant equations

    We are given:

    Let H(n) be the number of handshakes for a group of n aliens to introduce themselves. Then H(n) = [n(n-1)(n-2)]/6

    3. The attempt at a solution

    I couldn't find anything in my textbook about how to derive a self-referential formula. I tried hand-calculating a few small values for H(n) by substituting n for 1, 2, 3, 4, 5 and 6.

    H(1) = 0
    H(2) = 0
    H(3) = 1
    H(4) = 4
    H(5) = 10
    H(6) = 20

    I'm not sure what to do next. How do I derive a self-referential formula from this information?
     
  2. jcsd
  3. Nov 20, 2011 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    First off, I'm not sure what this introducing yourself is supposed to mean. If you have 2 aliens and they want to introduce themselves, shouldn't they shake hands? Then they are introduced. That would mean H(2)=1. Your formula would seem to suggest they have to introduce in groups of three. Might be why they are 'alien'. Can you state the whole problem?
     
  4. Nov 21, 2011 #3
    To find a self referential formula, try to express H(n) as a function of H(n-1)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Discrete Math: Self-referential formula
  1. Discrete Math (Replies: 0)

  2. Discrete Maths (Replies: 9)

  3. Discrete Math (Replies: 1)

  4. Discrete Math Question (Replies: 6)

Loading...