讲义the yield spread increase at lower credit rating is far greater than the spread decrease in the event of a credit update.这句话怎么理解呢？ 在信用上升的时候，低评级债的spread增加要大于spread的减少？

不明白为什么lowsafetyreturn会不频繁调整，而high的也会少操作

老师，在讲recessionhedge时，课件中写的是strong aggregate demand导致通胀，TP小，另一个老师的课件里写的是因为需求导致通胀时经济好，但本视频中说的是因recession导致长期债收益率低，所以TP小，是不是相违背了

老师这一段什么意思As long as none of the factors used in a factor-based VCV model are redundant and none of the asset returns are completely determined by the common factors, there will not be any portfolios that erroneously appear to be riskless. Therefore, a factor-based VCV matrix approach may result in some portfolios that erroneously appear to be riskless if any asset returns can be completely determined by the common factors or some of the factors are redundant.

冲刺笔记下册35页，为什么在31天后卖掉替代证券并换回原始证券，仍然会产生税务负担？

2. 老师好，PPP：不同地方货品价值应该一样，real rate 一样，所以inf(d)>inf(f),会导致 e(1)>e(0) 然后本币贬值 uip：nominal int 越高，然后贬值？ 不是应该利率越高大家涌进来，导致升值吗？ 另外 课后题有一题老师好，Short-term (1-month) government rate 上升 导致这个国家货币变强，这个gov rate 指的是 nominal int ?

老师好，这句话怎么理解high-frequency data improves the precision of sample variances, covariances, and correlations but not the precision of the sample mean

请问老师R20，这里PIC是指累计吗？比如：承诺支付本金100mil，年支付比率20%。第一年付20mil=100mil*20%,第二年付16mil=80mil*20%，第三年支付12.8mil=64mil*20%，如此类推。这样理解吗？

SS FIXED INCOME，R13，讲义，麻烦老师解释一下黄色highlight的这句话，谢谢老师

为什么这里用 104.15转换呢？