By consulting Fig. 18.2, find the subcases to which the following sets of values of a and y pertain, and describe the interaction time path qualitatively.
(a) a = 3.5; y = 0.8
(c) a = 0.2; y = 0.9
(b) α = 2; y = 0.7
(d) a = 1.5; y = 0.6