Here we verify the conditions under which t3' in equation (2-33) will be negative, (a)...

Here we verify the conditions under which t3' in equation (2-33) will be negative, (a) Show that t3'<0 is equivalent to the following:

(b) By construction, v cannot exceed u0, for if it did, the information could not catch up with Amy at event 2. Use this to argue that if u0 < c, then t3' must be positive for whatever value v is allowed to have, (c) Using the fact that (x - 1)2 ≥ 0, show that the right side of the expression in part (a) never exceeds 1. This confirms that when u0 > c, v need not exceed c to produce a negative t3'.