En cherchant une caractérisation variationnelle des martingales
Exponential martingales and CIR model
With the use of exponential martingales and the Girsanov theorem we show how to calculate bond prices in a large variety of square root processes. We clarify and correct several errors that abound in financial literature concerning these processes. The most important topics are linear risk premia, the Longstaff double square model, and calculations concerning correlated CIR processes.
Extending Lévy's characterisation of brownian motion