Affiliation: | aCollege of Mathematics, Changsha University of Science Technology, Changsha, 410076, China bCollege of Mathematics and Econometrics, Hunan University, Changsha, 410082, China |
Abstract: | By employing the Deimling fixed point index theory, we consider a class of second-order nonlinear differential systems with two parameters . We show that there exist three nonempty subsets of : Γ, Δ1 and Δ2 such that and the system has at least two positive periodic solutions for (λ,μ)Δ1, one positive periodic solution for (λ,μ)Γ and no positive periodic solutions for (λ,μ)Δ2. Meanwhile, we find two straight lines L1 and L2 such that Γ lies between L1 and L2. |