Questions of existence and uniqueness of the solution of one class of an infinite system of nonlinear two-dimensional equations

The paper is devoted to the study of one class of infinite systems of nonlinear two-dimensional equations with convex and monotone nonlinearity. The studied class of nonlinear systems of algebraic equations has both theoretical and practical significance, in particular, in the study of discrete analogs of problems in dynamic theory of $p$-adic open-closed strings, in the kinetic theory of gases, in mathematical biology in the study of space-time distribution of epidemics. Existence and uniqueness theorems for a positive solution in a certain class of non-negative and bounded matrices are proved. Some qualitative properties of the solution are revealed. The obtained results supplement and generalize some of the previously obtained ones. Illustrative examples of the corresponding matrices and nonlinearities (including those of an applied nature) that satisfy all the conditions of the formulated theorems are given.