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On finite exponential moments for branching processes and busy periods for queues

Published online by Cambridge University Press:  14 July 2016

Marvin K. Nakayama
Affiliation:
Department of Computer Science, New Jersey Institute of Technology, Newark, NJ 07102, USA. Email address: [email protected]
Perwez Shahabuddin
Affiliation:
Department of Industrial Engineering and Operations Research, Columbia University, 500 West 120th Street, New York, NY 10027-6699, USA. Email address: [email protected]
Karl Sigman
Affiliation:
Department of Industrial Engineering and Operations Research, Columbia University, 500 West 120th Street, New York, NY 10027-6699, USA. Email address: [email protected]

Abstract

Using a known fact that a Galton–Watson branching process can be represented as an embedded random walk, together with a result of Heyde (1964), we first derive finite exponential moment results for the total number of descendants of an individual. We use this basic and simple result to prove analogous results for the population size at time t and the total number of descendants by time t in an age-dependent branching process. This has applications in justifying the interchange of expectation and derivative operators in simulation-based derivative estimation for generalized semi-Markov processes. Next, using the result of Heyde (1964), we show that, in a stable GI/GI/1 queue, the length of a busy period and the number of customers served in a busy period have finite exponential moments if and only if the service time does.

Type
Part 5. Properties of random variables
Copyright
Copyright © Applied Probability Trust 2004 

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References

Athreya, K. B. and Ney, P. (1972). Branching Processes. Springer, New York.CrossRefGoogle Scholar
Billingsley, P. (1986). Probability and Measure , 2nd edn. John Wiley, New York.Google Scholar
De La Peña, V. H. (1994). A bound on the moment generating function of a sum of dependent variables with an application to simple random sampling without replacement. Ann. Inst. H. Poincaré Prob. Statist. 30, 197211.Google Scholar
Gut, A. (1988). Stopped Random Walks. Springer, New York.Google Scholar
Harris, T. E. (1952). First passage and recurrence distributions. Trans. Amer. Math. Soc. 73, 471486 Google Scholar
Heyde, C. C. (1964). Two probability theorems and their applications to some first passage problems. J. Austral. Math. Soc. 4, 214222.Google Scholar
Kiefer, J. and Wolfowitz, J. (1956). On the characteristics of the general queueing process with applications to random walks. Ann. Math. Statist. 27, 147161.CrossRefGoogle Scholar
Lindvall, T. (1976). On the maximum of a branching process. Scand. J. Statist. 3, 209214.Google Scholar
Nakayama, M. K. and Shahabuddin, P. (1998). Likelihood ratio derivative estimation for generalized semi-Markov processes. Manag. Sci. 44, 14261441.Google Scholar
Pakes, A. G. (1996). A hitting time for Lévy processes, with applications to dams and branching processes. Ann. Fac. Sci. Toulouse Math. 5, 521544.Google Scholar
Quine, M. P. and Szczotka, W. (1994). Generalisations of the Bienaymé-Galton-Watson branching process via its representation as an embedded random walk. Ann. Appl. Prob. 4, 12061222.Google Scholar
Selivanov, B. I. (1969). Some explicit formulas in the theory of branching random processes with discrete time and one type of particles. Theory Prob. Appl. 14, 336342.CrossRefGoogle Scholar
Wolff, R. W. (1989). Stochastic Modeling and the Theory of Queues. Prentice Hall, Englewood Cliffs, NJ.Google Scholar