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dushyant kochar
Member
Now if Yt is also a martingale with respect to Q (ie based on the same probabilities q and 1 - q ) then, first, Yt must also follow a binomial model with:
Y t+1 =
since both Xt and Yt must be measurable with respect to the same sigma- algebra Ft for all t .
can anyone explain how come Xt and Yt both are measurable by the same filtration? and why they have the same probability "q" for ups and the remaining for down?
Y +u(t, Y ) with probability q
Yt +d(t,Yt) with probability 1-q
since both Xt and Yt must be measurable with respect to the same sigma- algebra Ft for all t .
can anyone explain how come Xt and Yt both are measurable by the same filtration? and why they have the same probability "q" for ups and the remaining for down?