# small parameter

## Dynamics of equation with two delays modelling the number of population

Issue. The paper investigates the behavior of solutions of a logistic equation with two delays from some neighborhood of the equilibrium state with a large value of the coefficient of linear growth. Such problems arise in modeling the population size taking into account the age structure, as a model of the number of insets, etc. Innovation. It is shown that the critical cases arising in the problem of the stability of an equilibrium state have infinite dimension: an infinitely large number of roots of the characteristic equation tend to the imaginary axis.

## Hypermultistability in laser’s models with large delay

We study model of monomode semiconductor laser with optoelectronic feedback, based on balanced equations with delay. We built sets of quasinormal forms in neighboorghood of bifurcation values. The possibility of coexistence of large amount of stable oscillating solutions is shown.