Measuring Hitting Times on Topological Graphs
The hitting time H(A,B) is the expected number of steps for a random walker starting at node A to first reach node B.
We approximate this by taking the minimum of multiple random walks, which gives a better estimate of the true graph distance.
On large random graphs, the hitting time distribution follows an exponential distribution:
This emerges because each step has roughly equal probability of "finding" the target node, leading to a memoryless process.
Mean/Std ratio ~ 1.0 confirms exponential behavior.
For a graph with N nodes and average degree k, the mean hitting time scales as:
On our 110k node Voronoi lattice (k ~ 12), the mean distance is approximately 15,000 steps, or about 0.14N.
While the graph-theoretic shortest path (BFS) might be ~100-200 hops, the random walk "effective diameter" is much larger.
This reflects the diffusive nature of random walks - they explore locally before finding distant targets.