The Phases and the Challenges
摘要
The 50 steps described, as we will see, have different statistical characteristics that will be examined in due course. The fundamental characteristic underlying all the others is the distinction between a step defined as a phase and a step defined as a challenge. To immediately grasp the difference between the two, let’s use the following analogy: suppose we have a path with various difficulties; for example (Fig. 2.1a, b):