Results from Monte Carlo path integral simulations on a (hot hot’)-(hot frigid)-(hot frigid) cassette. (A) Footprints of AID on the sequence. (B) Observed per-site mutation frequencies. (C) Far left: Entropy densities of a word starting at the center of the (hot hot’) region going to the right (5’ to 3’) or the left (3’ to 5’) as a function of word length. Blue solids lines are results for a 60 s incubation time. Dashed and dotted dashed lines are for 30 s and 15 s, respectively. Middle: Orange line shows entropy densities of words staring at the center of the (hot frigid) region in the middle of the cassette for incubation times of 60 s (solid orange), 30 s (dashed) and 15 s (dotted dashed). Far right: Green line, dashed and dotted dashed line show entropy densities of words staring at the center of the (hot frigid) region on the far right of the cassette after 60 s, 30 s and 15 s, similar to the other two panels. The length of the word is shortest on the far right, indicating that AID’s diffusion is slow there. In the middle of the cassette, correlations among mutations are weak generating long words, suggesting that AID’s diffusion is fast here.