Abstract: A bifurcation problem for the equation $$ \Delta u+\lambda u-\alpha u^++\beta u^-+g(\lambda ,u)=0 $$ in a bounded domain in $\R ^N$ with mixed boundary conditions, given nonnegative functions $\alpha ,\beta \in L_\infty $ and a small perturbation $g$ is considered. The existence of a global bifurcation between two given simple eigenvalues $\lambda ^{(1)},\lambda ^{(2)}$ of the Laplacian is proved under some assumptions about the supports of the functions $\alpha ,\beta $. These assumptions are given by the character of the eigenfunctions of the Laplacian corresponding to $\lambda ^{(1)}, \lambda ^{(2)}$.
Keywords: nonlinearizable elliptic equations, jumping nonlinearities, global bifurcation, half-eigenvalue
Classification (MSC2000): 35B32, 35J65
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