Akkerman A
Br J Philos Sci. 1994;45:679-91. doi: 10.1093/bjps/45.2.679.
"Considering age groups as part of cohorts, implicit in LLM [a Leslie-Lotka finitist model], causes difficulty, manifested by the extensionality paradox. The proposition made here was that cohorts are empirical temporal entities, while age groups are theoretical entities, references only. Cohort is a multitude of persons born at the same time interval, throughout the totality of their lives. Age group, on the other hand, is a concept only, constituted by the notion of the age interval....A model of household and population growth based on the household composition matrix yields results that are inherently different from these of LLM."
将年龄组视为队列的一部分，这在LLM（一种莱斯利 - 洛特卡有限主义模型）中是隐含的，会引发困难，表现为外延性悖论。这里提出的观点是，队列是经验性的时间实体，而年龄组是理论实体，只是参考对象。队列是在同一时间间隔出生的众多人群，贯穿他们的一生。另一方面，年龄组只是一个概念，由年龄间隔的概念构成……基于家庭构成矩阵的家庭和人口增长模型产生的结果与LLM的结果本质上不同。
