S\&P 500 index data sampled at one-minute intervals over the course of 11.5 years (January 1989- May 2000) is analyzed, and in particular the Hurst parameter over segments of stationarity (the time period over which the Hurst parameter is almost constant) is estimated. An asymptotically unbiased...

In this paper we consider the stochastic sequence {Pt}E N defined recursively by the linear relation Pt+1 = At Pt + Bt in a random environment which is described by the non-stationary process V = {(At, Bt) t E N.. We formulate sufficient conditions on v which ensure that the finite-dimensional...

We consider the stochastic sequence {Yi}t E N defined recursively by the linear relation Yt+l = AtYt + Bt in a random environment. The environment is described by the stochastic process {(At, Bt ) }t E N and is under the simultaneous control of several agents playing a discounted stochastic...

Oil prices remained relatively low but volatile in the 2015-17 period, largely due to declining and uncertain demand from China. This follows a prolonged decline from around $110 per barrel in June 2014 to below $30 in January 2016, due in large part to increased supply of shale oil in the US,...