Due Wednesday October 2nd, 2024

  1. IF YOU ARE IN 4440:  Think about forming a group of 2-3 people for a poster.  Read the poster info in the “Posters” tab above.  Reach out on discord, in person, etc., if you like to find a group that way.  Then fill in this form with your poster group situation so I can find out who is working with who or who needs helping finding a team.
  2. IF YOU ARE IN 5440:  You do an individual project *instead of a poster*.  Send me an email with your thoughts on topic and your background and we can brainstorm.
  3. Think about your topic.
  4. Use the birthday paradox approximation formula (with the natural log e in it) to determine the minimal number of people who need to be in the classroom to have at least a 50% chance of a shared Ceres birthday.  (You’ll need to look up how many earth days in a Ceres orbit.)
  5. This problem outlines a proof that there are infinitely many primes from a CS perspective, using information theory (due to Chaitin).
    1. Define the Komolgorov complexity $C(n)$ of an integer $n$ to be the length of the shortest computer program that will output $n$ in decimal form.  (For concreteness, you can fix any programming language.)  For example, the program for $2701$ might simply be ‘print(‘2701′)’.  This gives a trivial upper bound on $C(n)$ of $O(\log n)$.  Explain why.
    2. For the numbers of the form $n=10^t$, prove that $C(n)$ is bounded above by $O(\log \log n)$ by giving an actual computer program.
    3. Suppose there are only finitely many primes $p_1, \ldots, p_k$.  The number $k$ is a constant.  Show that for all $n$, $C(n)$ is bounded above by $O(\log \log n)$, by using unique factorization.
    4. Prove that there must exist $n$ having $C(n) \ge \log n$, by using a counting argument.
    5. Explain why this proves there are infinitely many primes.