Ricerc@Sapienza

We consider the following critical elliptic system: {−Δui=μiui3+βui∑j≠iuj2inΩεui=0 on ∂Ωε,ui>0 in Ωεi=1,…,m, in a domain Ωε⊂R4 with a small shrinking hole Bε(ξ0). For μi>0, β<0, and ε>0 small, we prove the existence of a non-synchronized solution which looks like a fountain of positive bubbles, i.e. each component ui exhibits a towering blow-up around ξ0 as ε→0.

We establish uniform a-priori estimates for solutions of the semilinear Dirichlet problem (−Δ)mu=h(x,u) in Ω, u=∂nu=⋯=∂nm−1u=0 on ∂Ω,where h is a positive superlinear and subcritical nonlinearity in the sense of the Trudinger–Moser–Adams inequality, either when Ω is a ball or, provided an energy control on solutions is prescribed, when Ω is a smooth bounded domain. Our results are sharp within the class of distributional solutions. The analogous problem with Navier boundary conditions is also studied.

For any smooth bounded domain (Formula presented.), we consider positive solutions to (Formula presented.)which satisfy the uniform energy bound (Formula presented.)for (Formula presented.). We prove convergence to (Formula presented.) as (Formula presented.) of the (Formula presented.)-norm of any solution. We further deduce quantization of the energy to multiples of (Formula presented.), thus completing the analysis performed in De Marchis et al. (J Fixed Point Theory Appl 19:889–916, 2017).

We compute the Morse index of 1-spike solutions of the semilinear elliptic problem
()
where is a smooth bounded domain and is sufficiently large.

When Ω is convex, our result, combined with the characterization in [21], a result in [40] and with recent uniform estimates in [37], gives the uniqueness of the solution to (), for p large. This proves, in dimension two and for p large, a longstanding conjecture.

Semilinear elliptic equations, positive solutions, asymptotic behavior