Thursday, April 24, 2008

5.7 Due on 4/25/2008

Difficult
I am not so sure about part (b) of the definition of martingale, why the expectation of future fortune is equal to Sn?  Is it because Sn+1 depends on Sn?  On example (3), how does E(Sn+1|S0, ..., Sn) become E(Sn+Xn+1|Sn)?  Also, on the proof of Theorem 10, I don't understand why the indicators are used here?

Reflective
I am really having difficulties understanding this section.  In the first paragraph of this section, it says that martingales are used extensively in the modern financial mathematics; but I don't see any connections between them.  I feel that maybe because I can't fully understand this section.  I hope I can understand them better after the lecture.

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