Further study on the crossing curves in two-delay differential equations with delay-dependent coefficients

Abstract

The crossing curves method, which allows delays to vary simultaneously, is generalized to the scenario that four terms exist in the characteristic equations with delay-dependent coefficients. The crossing curves on the two-delay parameter plane are first plotted by our generalized algorithms. The criteria to determine the crossing direction are also given. Finally, an example is provided to support our method and illustrate its fortes.