“…We use a stochastic portfolio model (see, for example, [1,2,4,6,7]) with a standard Brownian motion {W 1s , F s } t≤s≤T defined on the probability space (Ω, F , F s , P), where {F s } t≤s≤T is the augmentation of filtration. The price of a risk-free asset is given by…”