Random Walk on a Complete Graph

This is the 4th math problem in a series of math problem blog posts that I am writing about.  I thought of this problem as a challenging weekly problem for math club, and I will present 2 solutions.  I came up with the first solution, and a friend of mine came up with the second solution -- a completely different approach that yielded the same answer.
You are randomly walking on a complete graph with \( 2 n \) vertices. You start at a random vertex and at each time step you transition to a different connected vertex. Let \( f(n) \) be the expected number of steps until you've visited exactly \( n \) distinct vertices. Find $$ \lim_{n \to \infty} \frac{f(n)}{n} $$
For those of you who are not familiar with graph theory, here is a complete graph with 6 vertices:


In the context of this problem, you start on one of the circles (it doesn't matter which due to symmetry) and at each time step, you cross one of the lines to a new circle.  Henceforth, I will refer to the circles as vertices, and the lines as edges.


Comments

Post a Comment

Popular posts from this blog

Efficiently Remove Duplicate Rows from a 2D Numpy Array

Multi-Core Programming with Java

Beat the Streak: Day Three