On probabilities of small deviations for compound cox processes

We derive logarithmic asymtotics for probabilities of small deviations for compound Cox processes. We show that under appropriate conditions, these asymptotics are the same as those for sums of independent random variables and processes with independent increments. When these conditions do not hold, the asymptotics of small deviations for compound Cox processes are quite different. Bibliography: 9 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 339, 2006, pp. 163–175.     

Sharp Small Deviation Asymptotics in the L 2-Norm for a Class of Gaussian Processes

We characterize the exact behavior of small deviations in a Hilbert norm for centered Gaussian processes in the case where their covariances have a special form of eigenvalues. This result enables us to describe small deviation asymptotics for certain Gaussian processes. Bibliography: 20 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 311, 2004, pp. 214–221.     

Small deviations of iterated processes in the space of trajectories

We derive logarithmic asymptotics of probabilities of small deviations for iterated processes in the space of trajectories. We find conditions under which these asymptotics coincide with those of processes generating iterated processes. When these conditions fail the asymptotics are quite different.     

On the small time behavior of Ornstein–Uhlenbeck processes with unbounded linear drifts

In this paper, we study the small time behavior of Ornstein–Ulenbeck processes with unbounded linear drifts on Hilbert spaces. The large deviations estimates are obtained. The general theory of Dirichlet forms, Lyons–Zheng′s decompositions and the convolution representation of the processes play an important role. Received: 12 February 1997 / Revised version: 27 November 1998     

Strassen's local law of the iterated logarithm for Lévy's area

We prove a Strassen's law of the iterated logarithm at zero for Lévy's area process. Contrary to the Brownian case, the time inversion argument doesn't seem to work. Here, the main tool in the proof is large deviations estimates for diffusion processes with small diffusion coefficients.     

Some asymptotic results for nonlinear Hawkes processes

Hawkes process is a class of simple point processes with self-exciting and clustering properties. Hawkes process has been widely applied in finance, neuroscience, social networks, criminology, seismology, and many other fields. In this paper, we study fluctuations, large deviations and moderate deviations nonlinear Hawkes processes in a new asymptotic regime, the large intensity function and the small exciting function regime. It corresponds to the large baseline intensity asymptotics for the linear case, and can also be interpreted as the asymptotics for the mean process of Hawkes processes on a large network.     

Large deviations of renewal processes

Limit theorems for large deviations of renewal processes are presented. One result is for a terminating renewal process with small probability of terminating. These theorems are analogous to the classical Cramer and Feller large deviation theorems for sums of independent random variables.     

Spectral asymptotics for problems with integral constraints

The eigenvalue problem for differential operators of arbitrary order with integral constraints is considered. The asymptotics of the eigenvalues is obtained. The results are applied to finding the asymptotics of the probability of small deviations for some detrended processes of nth order.     

On asymptotic behavior for probabilities of large deviations of compound Cox processes

We derive logarithmic asymptotics for probabilities of large deviations for compound Cox processes. We show that under appropriate conditions, these asymptotics are the same as those for sums of independent random variables and processes with independent increments. When these conditions fail, the asymptotics of large deviations probabilities for compound Cox processes are quite different. Bibliography: 5 titles. Translated from Zapiski Nauehnykh, Seminarov POMI, Vol. 361, 2008, pp. 167–181.     

On the History of St. Petersburg School of Probability and Mathematical Statistics: II. Random Processes and Dependent Variables

This is the second paper in a series of reviews devoted to the scientific achievements of the Leningrad and St. Petersburg school of probability and mathematical statistics from 1947 to 2017. This paper is devoted to the works on limit theorems for dependent variables (in particular, Markov chains, sequences with mixing properties, and sequences admitting a martingale approximation) and to various aspects of the theory of random processes. We pay particular attention to Gaussian processes, including isoperimetric inequalities, estimates of the probabilities of small deviations in various norms, and the functional law of the iterated logarithm. We present a brief review and bibliography of the works on approximation of random fields with a parameter of growing dimension and probabilistic models of systems of sticky inelastic particles (including laws of large numbers and estimates for the probabilities of large deviations).     

Optimal importance sampling for Lévy processes

We develop importance sampling estimators for Monte Carlo pricing of European and path-dependent options in models driven by Lévy processes. Using results from the theory of large deviations for processes with independent increments, we compute an explicit asymptotic approximation for the variance of the pay-off under a time-dependent Esscher-style change of measure. Minimizing this asymptotic variance using convex duality, we then obtain an importance sampling estimator of the option price. We show that our estimator is logarithmically optimal among all importance sampling estimators. Numerical tests in the variance gamma model show consistent variance reduction with a small computational overhead.     

Large deviation for pinned covering diffusion

We shall establish large deviations for the pinned motions of a periodic diffusion process on n dimensional Euclidean space and the Brownian motion on 2 dimensional Lobachevsky space. It will be shown that the rate functions for the large deviations are corresponding to the infinitesimal generators of the diffusion processes obtained from the above processes through a kind of harmonic transform by positive principal eigenfunctions.     

Integro-Local Limit Theorems for Compound Renewal Processes under Cramér’S Condition. I

We obtain integro-local limit theorems in the phase space for compound renewal processes under Cramér’s moment condition. These theorems apply in a domain analogous to Cramér’s zone of deviations for random walks. It includes the zone of normal and moderately large deviations. Under the same conditions we establish some integro-local theorems for finite-dimensional distributions of compound renewal processes.     

On asymptotic behavior of probabilities of large and moderate deviations for some iterated stochastic processes

We derive logarithmic asymptotics for probabilities of large deviations for some iterated processes. We show that under appropriate conditions, these asymptotics are the same as those for sums of independent random variables. When these conditions do not hold, the asymptotics of large deviations for iterated processes are quite different. When the iterated process is a homogeneous process with independent increments in which time is replaced by random one, the behavior of large and moderate deviations is studied in the case of finite variance. For this case, the following one-sided moment restriction are considered: the Cramèr condition, the Linnik condition, and the existence of moment of order p > 2 for a positive part. Bibliography: 6 titles.     

Moderate deviations for estimators of quadratic variational process of diffusion with compound Poisson jumps

We consider the stochastic differential equation driven by Lévy processes. Using discrete observations, moderate deviations for the threshold estimator of the quadratic variational process are studied. Moreover, we also obtain the functional moderate deviations.     

Large deviations in the problem of distinguishing the counting processes

We prove the general limit theorem on probability of large deviations of the logarithm of the likelihood ratio with the null hypothesis and alternative. Weaker versions of the principle of large deviations are obtained in predictable terms for the problem of distinguishing the counting processes. The case of counting processes with deterministic compensators is studied.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 11, pp. 1514–1521, November, 1993.     

On evaluating the rate function of large deviations for jump processes

This is a sequel to our joint paper^[4] in which upper bound estimates for large deviations for Markov chains are studied. The purpose of this paper is to characterize the rate function of large deviations for jump processes. In particular, an explicit expression of the rate function is given in the case of the process being symmetrizable.     

Action functional for diffusions in discontinuous media

Summary The action functional, i.e. the rate function governing the large deviations is obtained for a family of stochastic processes with discontinuous drift and small diffusion. A well-known method of continuous mapping is developed which proves to be efficient in a so called stable case.     

Poisson convergence,in large deviations,for the superposition of independent point processes

For a small buffer queueing system fed by many flows of a large class of traffic processes we show the single server queue and associated sample paths behave as if fed by marked Poisson traffic in a large deviations limit. The timescale of events of interest tends to zero, so we study the log moment generating function as time tends to zero. The associated rate function depends only on the mean arrival rate and the moment generating function of the arrivals. These results are useful in estimating drop probabilities while studying the effect of small buffers on communication protocols. Research supported by EPSRC Grant GR/S86266/01.     

Rough asymptotics for tandem non-homogeneous $$M/G/\infty$$ queues via Poissonized empirical processes

We obtain a large deviations principle and moderate deviations principle for the joint distribution of the queue length processes and departure process for tandem queues. The results are obtained by applying a result providing necessary and sufficient conditions on a class of functions for a large deviations principle and moderate deviations principle to hold for a Poissonized empirical process over the class of functions. As an application, we examine how large queue lengths and numbers of departures are built up. This revised version was published online in June 2006 with corrections to the Cover Date.