Center manifolds theorem for parameterized delay differential equations with applications to zero singularities

The goal of this paper is to develop a center manifold theory for delay differential equations with parameters. As applications, we use the center manifold theorem to establish fold and Bogdanov-Takens bifurcations. In particular, we obtain the versal unfoldings of delayed predator-prey systems with predator harvesting at the Bogdanov-Takens singularity.