Can you streamline your question?

1) provide the screenshot of Jiang's words that he said lookback option pricing formula can be used directly
2) reorganize your question. Some of the sentences are broken.

Thanks very much

非常抱歉  我也知道我表达的十分混乱。。。。
有些地方我已经弄明白了 就是还有一点 就是在建立回望期权定价模型的时候 这上面最后一个式子的含义  原文的解释是这个式子代表期权定价在原生资产价格达到极大值水平上对极大值的变化是不敏感的
我始终理解不了这句话。。
V就是回望期权的价值了 他是标的S  路径依赖变量J 和T 的函数 这是针对回望看跌期权建立的模型
望版主给解惑下  谢谢~~

Well, let's say J(t) is the max value of S on interval [0, t] and the current time is t, the current stock price is S(t), and T is the option's expiry date. T>t

if J(t)=S(t) the probability of J(t) still be the max value at expiry will be zero, because current stock price=J(t), if the stock price goes up a little, J(t) will no longer be the max value. If J(t) is not the max value, the loopback's payoff at expiry will not be affected by it. So that's why it should show 0 sensitivity.

If you have other questions just let me know.

似乎有那么点明白了  我再多看看。。。
非常感谢~~