Total progeny in the near-critical multi-type Galton-Watson processes with immigration

In this paper, we study Galton-Watson branching processes with immigration. These processes are an extension of the classical Galton-Watson model, incorporating an additional mechanism where new individuals, called immigrants, enter the population independently of the reproduction dynamics of existi...

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Bibliographic Details
Main Author: T. B. Lysetskyi
Format: Article
Language:deu
Published: Ivan Franko National University of Lviv 2024-12-01
Series:Математичні Студії
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Online Access:http://matstud.org.ua/ojs/index.php/matstud/article/view/572
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Summary:In this paper, we study Galton-Watson branching processes with immigration. These processes are an extension of the classical Galton-Watson model, incorporating an additional mechanism where new individuals, called immigrants, enter the population independently of the reproduction dynamics of existing individuals. We focus on the multi-type case, where individuals are classified into several distinct types, and the reproduction law depends on the type. A crucial role in the study of multi-type Galton-Watson processes is played by the matrix $M$, which represents the expected number of descendants of different particle types, and its largest positive eigenvalue, $\rho$. Sequences of branching processes with primitive matrices $M$ and eigenvalues $\rho$ converging to $1$ are referred to as near-critical. Our focus is on the random vector $Y_n$, representing the total number of particles across all generations up to generation $n$, commonly called the total progeny, in near-critical multi-type Galton-Watson processes with immigration. Assuming the double limit $n(\rho - 1)$ exists as $n \to \infty$ and $\rho \to 1$, we establish the limiting distribution of the properly normalized vector~$Y_n$. This result is derived under standard conditions imposed on the probability generating functions of the offspring and immigration component.
ISSN:1027-4634
2411-0620