Authors:
Jaksa Cvitanić,
Robert S. Liptser,
Boris Rozovskii,
Volume: 1, Page 1189 Paper number 3801
Abstract:
This paper is concerned with nonlinear filtering of the volatility
coefficient in a Black-Scholes type model that allows stochastic volatility.
The stochastic volatility is modeled as a nonnegative function of a
homogeneous Markov jump process. Following to Frey and Runggaldier,
we assume that the asset price is measured only at random times. This
assumption is designed to reflect the discrete nature of high frequency
financial data (e.g. tick-by-tick stock prices). In the above setting
the problem of volatility estimation is reduced naturally to a nonlinear
filtering problem. We remark that while quite natural, the latter problem
does not fit into the ''standard'' framework and requires new technical
tools. In this paper, we derive a mean-square optimal recursive Bayesian
filter for the volatility process. In particular, we derive Duncan-Mortensen-Zakai
and Wonham-Kushner type equations for posterior distributions of the
volatility process.
Authors:
William M. McEneaney,
Volume: 1, Page 1194 Paper number 3803
Abstract:
We consider max-plus based algorithms for the solution of nonlinear
H-infinity problems. This class of algorithms has been described for
several problem types such as nonlinear H-infinity filtering, nonlinear
H-infinity control and nonlinear H-infinity control under partial information.
Previous treatments have been oriented towards the general introduction
of the algorithms. It has been noted that the corresponding convergence
analysis was lacking in those papers. Here we demonstrate, in the case
of nonlinear H-infinity control, that the errors introduced by the
truncation to a finite number of max-plus basis functions go to zero
as the number of basis functions increases. Some error bounds are also
obtained.
Authors:
Frédéric Cérou,
François LeGland,
Volume: 1, Page 1200 Paper number 3804
Abstract:
In this paper, the problem of detecting a change in the drift coefficient
of a partially observed stochastic differential equation is addressed.
The score function, evaluated at the nominal value, is used as the
residual, and only the problem of residual generation is considered.
In the special case where the drift coefficient depends on the parameter
only in directions that are affected by nondegenerate noise, an efficient
numerical approximation of the residual is proposed, using particle
filters. The more complicated problem of residual evaluation will be
considered elsewhere, under the small noise asymptotics.
Authors:
Hideo Nagai,
Volume: 1, Page 1206 Paper number 3805
Abstract:
We shall show some results applying risk-sensitive control with partial
observation to mathematical finance, discussing portofolio optimization
problems for factor models recently treated by Bielecki and Pliska(1999).
They have formulated the factor models where securities prices are
governed by the stochastic differential equations like geometric Brownian
motion processes, whose drift coefficients (indicating expected growth
rate in the case of geometric B.M.) are affine functions of the underlying
economic factors such as price-earning ratios, short term interest
rates, dividend yields, and macroeconomic measures and diffusion coefficients
are constant indicating volatility of the securities. The set of such
securities may include stocks, bonds, cash, and derivative securities.
On the other hand the factors are assumed to be governed by the stochastic
differential equations with linear drift coefficients. Then they consider
the problem maximizing the risk-sensitized long run expected growth
rate of capital value which the investor possesses by taking a portfolio
strategy among the above defined securities. Representing the maximum
as the function of the initial values of the factors and the value
process, they introduce a Belleman equation of ergodic type. By using
the solution of the Bellman equation they construct an optimal strategy.
In their case the admissible investment strategies have been considered
to be selected by using past informations of the securities to invest
and also the factors. In the present paper we shall discuss similar
problems to Bielecki and Pliska's, taking up such factor models and
considering the optimization problems on finite time horizon. However,
in our setting, our admissible strategies are considered to be chosen
by using only past informations of securities to invest. We shall
formulate our problems as risk-sensitive control problems of partially
observable systems by regarding the factors as the system processes
and the logarithm of securities prices as the observation processes
and then obtain optimal strategies for the control problems having
explicit representation by the solutions of ordinary differential equations
and the ones of stochastic differential equations. Indeed we shall
first express our criterion function by using the solution of a modified
Zakai equation. Then, after giving the solution an explicit representation
by means of the solution of a matrix Riccati differential equation
and the one of a finite dimensional stochastic differential equation,
we shall show the optimal strategy can be explicitly represented by
the solutions and the ones of other three kinds of ordinary differential
equations. We note that our results relate to Bensoussan and Van Schuppen's
work (1985) having discussed the LEQG problem of a partially observable
system. Difference from the work lies in that our noises are correlated
and the performance index includes a stochastic integral.
Authors:
X. Rong Li,
Chongzhao Han,
Jie Wang,
Volume: 1, Page 1212 Paper number 3806
Abstract:
The Kalman filter is a recursive Best Linear Unbiased Estimator (BLUE)
for a linear dynamic system with uncorrelated white process and measurement
noises. It has been extended to the case where the noises are Markov
and/or crosscorrelated for the same time instant. This paper presents
optimal batch and semi-recursive filters and a suboptimal recursive
filter for a linear discrete-time system with arbitrarily colored (not
necessarily Markov) noises that are arbitrarily cross-correlated and
correlated with the initial state of the system. They are generalizations
of the Kalman filter for the case of arbitrary additive noise of known
first two moments. Numerical examples are provided. They demonstrate
the superiority in terms of performance and efficiency of the proposed
recursive filter.
Authors:
Kazufumi Ito,
Volume: 1, Page 1218 Paper number 3807
Abstract:
In this paper we develop and analyze real-time and accurate filters
for nonlinear filtering problems based on the Gaussian distributions.
We present the systematic formulation of Gaussian filters and develop
efficient and accurate numerical integration of the proposed filter.
We also discuss the mixed Gaussian filters in which the conditional
probability density is approximated by the sum of Gaussian distributions.
Our numerical testings demonstrate that new filters significantly improve
the extended Kalman filter with no additional cost and the new Gaussian
sum filter has a nearly optimal performance.
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