R13 Example 6 Surplus optimization 3
solution 3 关于EF, surplus return 增加，corportate bonds投的越少的解释不明白。 The observed relationship that the allocation to corporate bonds declines with increasing surplus return can be explained by the positive correlation of bond price with the present value of liabilities. 债券价格和债务价值正相关怎么能解释surplus return 增加，corportate bonds投的越少?
