  In this article three models of firms interaction on the market are
described. One of these models is described by using a differential equation
and by Lotka-Volterra model, where the equation has a different form. Also,
there are models of non-competing and competing firms. The article presents an
algorithm for solving the interaction of competing firms in taxation and the
calculation of a compromise point. Besides, the article presents a compromise
between the interests of a state and an enterprise.
