论文标题

关于灾难的人口增长

On population growth with catastrophes

论文作者

Goncalves, Branda, Huillet, Thierry, Löcherbach, Eva

论文摘要

在本文中,我们研究了一类特定的分段确定性马尔可夫过程(PDMP),这些过程是确定性种群增长模型的半传染性灾难版本。在连续的跳跃之间,该过程遵循描述确定性人口增长的流程。此外,在随机的跳跃时间,受状态依赖性率的约束,人口的大小缩小了其当前大小的随机数量,这一事件可能导致瞬时局部(或总)灭绝。更详细地研究了一种特殊的可分离收缩式转换内核,包括全灾。我们讨论了此类过程是复发(正或零)或瞬态的条件。为此,我们引入了一个修改的比例功能,该功能用于计算旅行高度的定律,并决定该过程是否复发。研究了灭绝时间的有限性问题,以及对最后一个是有限的灭绝时间的评估。在处理我们展示的状态0和无穷大的分类时,还需要有关PDMP嵌入式跳跃链的一些信息。

In this paper we study a particular class of Piecewise deterministic Markov processes (PDMP's) which are semi-stochastic catastrophe versions of deterministic population growth models. In between successive jumps the process follows a flow describing deterministic population growth. Moreover, at random jump times, governed by state-dependent rates, the size of the population shrinks by a random amount of its current size, an event possibly leading to instantaneous local (or total) extinction. A special separable shrinkage transition kernel is investigated in more detail, including the case of total disasters. We discuss conditions under which such processes are recurrent (positive or null) or transient. To do so, we introduce a modified scale function which is used to compute, when relevant, the law of the height of excursions and to decide if the process is recurrent or not. The question of the finiteness of the time to extinction is investigated together with the evaluation of the mean time to extinction when the last one is finite. Some information on the embedded jump chain of the PDMP is also required when dealing with the classification of states 0 and infinity that we exhibit.

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