ABSTRACT

A closed one-dimensional curve on graph we call a cycle. A cycle is said to be homologous to zero if it coincides with the border of a part of the integral curve, where K is a compact set. Two cycles on the integral curve are said to be homologous to one another if their union forms the border of a compact part of the integral curve. A cycle of the real equation that is stable with respect to a* cannot be homotopic to zero on an integral curve of the corresponding complex equation. For the real equation, the maximal number of limit cycles that are stable with respect to a does not exceed the maximal number of cycles for the complex equation that are simple, correctly located and non-homotopic to zero and each other.