Exercise 9.3.8 Here is yet another way to assign u and d: u = e /n+(1/n)

Exercise 9.3.8 Here is yet another way to assign u and d:

u = eσ

√

τ/n+(1/n) ln(X/S), d = e−σ

√

τ/n+(1/n) ln(X/S), q = erτ/n −d u−d

.

(1) Show that it works. (2)What is special about this choice?