Hi! I have some questions from Chapter 15.. 1) in deriving equation 2.3, there are some mathematical workings involving ^ and v. Though the workings make sense, I'm not sure if I'm able to come up with something like this in the exam. So I'm wondering if we're expected to understand/ find out more about the mathematical workings involving ^ and v? 2) Eqn 2.3 makes sense where the layer loss cost = ground up loss * differences in the exposure curve with relativities (L+D)/M and D/M. However, for equation 2.4, I don't understand why you need to devide by [1-G(d/(M+d))]? Is there any intuitive explanation behind eqn 2.4? 3) also in page 20, the notes say 'the presence of original deductibles will increase the reinsurance rates', it means that reinsurance will be more expansive where there's original deductibles? I don't see why is that the case, although the insurer is not liable for the original deductible, so is the reinsurer and why does that make reinsurance more expansive? 4) in page 21 under the heading of Treatment of stacked limits, the notes say 'if the layers are stacked then the underlying contract is essentially 1.4m xs 100k and the reinsurance covers the range [600k, 1.1m]. If they are independent, the reinsurance only affects the 1m xs 500k contract, covering the range [1m,1.5m]' how is the range [600k,1.1m] obtained? Also when the contracts are independent, shouldn't the reinsurance cover the range [0.5m,1.5m] instead of [1m,1.5m]? 5) under Catastrophe XL rating, what does it mean by 'long return periods' and why does it make curves difficult to estimate? 6) eqn 6.2 says C(delta I) = E(N)E[X^(delta I +D) - X^D] = E(N)[S(D)delta I] I don't see how to get the second line? Thanks in advance!