Explain why a sticky cap is more expensive than a similar ratchet cap.
In a ratchet cap, the cap rate equals the previous reset rate, $R$, plus a spread. In the notation of the text it is $R_j+s$. In a sticky cap the cap rate equal the previous capped rate plus a spread. In the notation of the text it is $\min \left(R_j, K_j\right)+s$. The cap rate in a ratchet cap is always at least a great as that in a sticky cap. Since the value of a cap is a decreasing function of the cap rate, it follows that a sticky cap is more expensive.