Published online by Cambridge University Press: 22 June 2018
We prove the uniqueness of a solution for a problem whose simplest model is
with k ≥ 1, 0 f ∈ L∞(Ω) and Ω is a bounded domain of ℝN, N ≥ 2. So far, uniqueness results are known for k < 1, while existence holds for any k ≥ 1 and f positive in open sets compactly embedded in a neighbourhood of the boundary. We extend the uniqueness results to the k ≥ 1 case and show, with an example, that existence does not hold if f is zero near the boundary. We even deal with the uniqueness result when f is replaced by a nonlinear term λuq with 0 < q < 1 and λ > 0.
Present address: Dipartimento di Scienze di Base e Applicate per l'Ingegneria ‘Sapienza’, Università di Roma I, Via Antonio Scarpa 10, 00161 Roma, Italy (tommaso.leonori@sbai.uniroma1.it).