On the dynamics of populations with two age groups.

By restricting the number of age groups to two and by introducing continued fractions, the dynamics of populations with deterministically changing vital rates are completely specified at all times. Explicit expressions for the sequence of the product of population projection matrices are given. From these, relative age distribution and reproductive values to any desired accuracy are obtained as functions of the vital rates. Thus, the results given in this paper are stronger than any existing weak ergodic theorems.