“…Its main required property [1] is that it causes the particle to change its energy and angular momentum continuously in time, so that if we monitor EðtÞ and mðtÞ, we find that they go counterclockwise around a circuit C in the ðm; EÞ plane encircling the origin (0, 0) as shown in (2) is one of the simplest examples of systems with nontrivial monodromy [4]. In such a system, as will be explained in more detail later, if we relate continuously the coordinates on the neighboring regular tori with energy E and angular momentum m while ðm; EÞ follow a closed directed path C encircling (0, 0), and then compare final and initial coordinates after completing one tour and returning to the same torus, we will find that the final and initial coordinates do not match.…”