EN
Let Ω be a bounded domain in $ℝ^{N}$ with smooth boundary. Consider the following elliptic system:
$-Δu = ∂_{v}H(u,v,x)$ in Ω,
$-Δv = ∂_{u}H(u,v,x)$ in Ω,
u = 0, v = 0 in ∂Ω. (ES)
We assume that H is an even "-"-type Hamiltonian function whose first order partial derivatives satisfy appropriate growth conditions. We show that if (0,0) is a hyperbolic solution of (ES), then (ES) has at least 2|μ| nontrivial solutions, where μ = μ(0,0) is the renormalized Morse index of (0,0). This proves a conjecture by Angenent and van der Vorst.