摘要

This paper is concerned with the upper bound of the number of limit cycles in unfolding of codimension 3 planar singularities with nilpotent linear parts. After making a central resealing, the problem reduces to a perturbation problem of a one-parameter family of quadratic reversible systems. As the parameter a is an element of (-1, 1) \ {0} is rational, except the case a = -2/3, based on the Chebyshev criterion for Abelian integrals and a rationalizing transformation, the problem could be solved theoretically. To illustrate our approaches, two particular cases (correspond.. ing to nilpotent codimension 3 saddle and elliptic case respectively) are proved where the upper bound of the number of limit cycles is two.