Markov additive process

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In applied probability, a Markov additive process (MAP) is a bivariate Markov process where the future states depends only on one of the variables.[1]

Definition

Finite or countable state space for J(t)

The process {(X(t),J(t)) : t  0} is a Markov additive process with continuous time parameter t if[1]

  1. {(X(t),J(t)) : t  0} is a Markov process
  2. the conditional distribution of (X(t + s)  X(t),J(s + t)) given (X(s),J(s)) depends only on J(s).

The state space of the process is R × S where X(t) takes real values and J(t) takes values in some countable set S.

General state space for J(t)

For the case where J(t) takes a more general state space the evolution of X(t) is governed by J(t) in the sense that for any f and g we require[2]

{\mathbb  E}[f(X_{{t+s}}-X_{t})g(J_{{t+s}})|{\mathcal  F}_{t}]={\mathbb  E}_{{J_{t},0}}[f(X_{s})g(J_{s})].

Example

A fluid queue is a Markov additive process where J(t) is a continuous-time Markov chain.

Applications

Çinlar uses the unique structure of the MAP to prove that, given a gamma process with a shape parameter that is a function of Brownian motion, the resulting lifetime is distributed according to the Weibull distribution.

Kharoufeh presents a compact transform expression for the failure distribution for wear processes of a component degrading according to a Markovian environment inducing state-dependent continuous linear wear by using the properties of a MAP and assuming the wear process to be temporally homogeneous and that the environmental process has a finite state space.

Notes

  1. 1.0 1.1 Magiera, R. (1998). "Optimal Sequential Estimation for Markov-Additive Processes". Advances in Stochastic Models for Reliability, Quality and Safety. pp. 167–181. doi:10.1007/978-1-4612-2234-7_12. ISBN 978-1-4612-7466-7. 
  2. Asmussen, S. R. (2003). "Markov Additive Models". Applied Probability and Queues. Stochastic Modelling and Applied Probability 51. pp. 302–339. doi:10.1007/0-387-21525-5_11. ISBN 978-0-387-00211-8. 
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