A new method for the upper estimation of growth for some infinite groups of the automorphisms of trees is investigated. A criterion which distinguishes when a group has exponential growth or subexponential is established.
The extremal problems of the theory of univalent functions are studied. Some known results concerning the extremal problems with free poles for nonoverlapping domains are extended to the special classes of open sets.
A mixed elliptic boundary-value problem for a differential equation over a multiply connected bounded domain is studied. The boundary conditions have different orders on the distinct connected components of the boundary. ...