Abstract

We consider the first-passage time problem for the Feller-type diffusion process, having infinitesimal drift B1(x,t)=α(t)x+β(t) and infinitesimal variance B2(x,t)=2r(t)x, defined in the space state [0,+∞), with α(t)∈R, β(t)>0, r(t)>0 continuous functions. For the time-homogeneous case, some relations between the first-passage time densities of the Feller process and of the Wiener and the Ornstein–Uhlenbeck processes are discussed. The asymptotic behavior of the first-passage time density through a time-dependent boundary is analyzed for an asymptotically constant boundary and for an asymptotically periodic boundary. Furthermore, when β(t)=ξr(t), with ξ>0, we discuss the asymptotic behavior of the first-passage density and we obtain some closed-form results for special time-varying boundaries.

Highlights

  • Dipartimento di Informatica, Università degli Studi di Salerno, Via Giovanni Paolo II n. 132, Abstract: We consider the first-passage time problem for the Feller-type diffusion process, having infinitesimal drift B1 ( x, t) = α(t) x + β(t) and infinitesimal variance B2 ( x, t) = 2 r (t) x, defined in the space state [0, +∞), with α(t) ∈ R, β(t) > 0, r (t) > 0 continuous functions

  • We focus our analysis on the asymptotic behavior of the first-passage time” (FPT) pdf for the Feller diffusion process, with α < 0, β > 0 and r > 0, by considering separately two cases: S(t) is an asymptotically constant boundary and S(t) is an asymptotically periodic boundary

  • We focus on the asymptotic behavior of the FPT pdf of the Feller-type diffusion process (69), with a zero-flux condition in the zero state, through the asymptotically constant boundary (61), with S(t) > 0, where η (t) ∈ C1 [t0, +∞) is a bounded function, that does not depend on S, such that (62) holds

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Summary

FPT Problem for a Time-Homogeneous Feller Process

We consider the time-homogeneous Feller process X (t) with drift B1 ( x ) = αx + β and infinitesimal variance B2 ( x ) = 2 r x, defined in the state space [0, +∞). As proved by Feller [44], the state x = 0 is an exit boundary for β ≤ 0, a regular boundary for 0 < β < r and an entrance boundary for β ≥ r. The scale function and the speed density of X (t) are (cf Karlin and Taylor [45]):. We assume that β > 0 and suppose that a zero-flux condition is placed in the zero state

Transition Density
Laplace Transform of the Transition Density
Laplace Transform of the FPT Density
Relations between the FPT Densities for the Feller and the Wiener Processes
FPT Moments for the Time-Homogeneous Feller Process
Mean of FPT Downwards
Moments of FPT Upwards
Asymptotically Constant Boundary
Asymptotically Periodic Boundary
First-Passage Time for a Time-Inhomogeneous Feller-Type Process
FPT Densities
Asymptotic Behavior of the FPT Density for a Time-Inhomogeneous
Conclusions
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