Generalized linking theorem and nonlinear equations in unbounded domains
An Index Theory and Existence of Multiple Brake Orbits for Star-Shaped Hamiltonian Systems
An example concerning the topological character of the zero-set of a harmonic function.
Local structure of the zero-sets of differentiable mappings and application to bifurcation theory.
Morse theory and existence of periodic solutions of convex hamiltonian systems
Minimax principles for lower semicontinuous functions and applications to nonlinear boundary value problems
Ljusternik-Schnirelmann theory on -manifolds
Eigenvalue problems with indefinite weight
We consider the linear eigenvalue problem -Δu = λV(x)u, , and its nonlinear generalization , . The set Ω need not be bounded, in particular, is admitted. The weight function V may change sign and may have singular points. We show that there exists a sequence of eigenvalues .
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