Contingent claims with payoffs depending on finitely many asset prices are modeled as elements of a separable Hilbert space. Under fairly general conditions, including market completeness, it is shown that one may change measure to a reference measure under which asset prices are Gaussian and...

This paper provides a characterization theorem for a complete securities market when security prices follow Itô processes on a multidimensional Brownian filtration. This characterization theorem is a special case of Harrison and Pliska (1983), and it clarifies a counterexample provided by...

An equivalent martingale measure selection strategy for discrete time, continuous state, asset price evolution models is proposed. The minimal martingale law is shown to generally fail to produce a probability law in this context. The proposed strategy, termed the extended Girsanov principle,...

This paper presents a resolution of the paradox proposed by the example of an economy with complette markets and a multiplicityof martingale measures constructed by Artzner and Heath (1995). The resolution lies in noting that completeness is with respect to a topology on the space of cash flows...