Statistics

Stopping-TimeAnalysis

First-descent times, histograms of long trajectories, and the exponential decay of the tail density.

1. Definitions

The stopping time of \(n\) is the smallest positive integer \(s\) such that \(T^{s}(n)<n\). Terras observed that the density of integers whose stopping time exceeds any fixed bound tends to zero.

2. Tail Density

The probability of a parity walk remaining above the critical line of slope \(\log_2 3\) for all time is zero under the uniform measure, yet the corresponding set is nonempty in the 2-adic integers.

3. Implementation

Usage: gcc -O2 -DLOGN=32 -o tailtest2 tailtest2.c && ./tailtest2