{ "id": "1603.04940", "version": "v1", "published": "2016-03-16T02:15:54.000Z", "updated": "2016-03-16T02:15:54.000Z", "title": "An indefinite concave-convex equation under a Neumann boundary condition I", "authors": [ "Humberto Ramos Quoirin", "Kenichiro Umezu" ], "categories": [ "math.AP" ], "abstract": "We investigate the problem $$-\\Delta u = \\lambda b(x)|u|^{q-2}u +a(x)|u|^{p-2}u \\mbox{ in } \\Omega, \\quad \\frac{\\partial u}{\\partial \\mathbf{n}} = 0 \\mbox{ on } \\partial \\Omega, \\leqno{(P_\\lambda)} $$ where $\\Omega$ is a bounded smooth domain in $\\mathbb{R}^N$ ($N \\geq2$), $1