This paper considers characterizations of perfect recall in extensive form games. It is shown that perfect recall can be expressed entirely in terms of the choice partition without any reference to any information sets. When information sets are taken into account it is decomposable into an...

In this paper it is shown that the space of stochastic integrals w.r. to a special semimartingal is closed and hence every square integrable random variable admits a best approximation in this space. In terms of financial economics this means that for every contingent claim there exists a...