We consider the boundary value problem (0.1) − ψ ( x , u ( x ) , u ′ ( x ) ) ′ = f ( x , u ( x ) , u ′ ( x ) ) , a.e. x ∈ ( 0 , 1 ) , (0.2) c 00 u ( 0 ) = c 01 u ′ ( 0 ) , c 10 u ( 1 ) = c 11 u ′ ( 1 ) , where | c j 0 | + | c j 1 | > 0 , for each j = 0 , 1 , and ψ , f : [ 0 , 1 ] × R 2 → R are Carathéodory functions, with suitable additional properties. The differential operator generated by the left-hand side of (0.1), together with the boundary conditions (0.2), is a generalisation of the usual p-Laplacian, and also of the so-called ϕ-Laplacian (which corresponds to ψ ( x , s , t ) = ϕ ( t ) , with ϕ an odd, increasing homeomorphism). For the p-Laplacian problem (and more particularly, the semilinear case p = 2 ), ‘nonresonance conditions’ which ensure the solvability of the problem (0.1), (0.2), have been obtained in terms of either eigenvalues (for non-jumping f) or the Fučík spectrum or half-eigenvalues (for jumping f) of the p-Laplacian. In this paper, under suitable growth conditions on ψ and f, we extend these conditions to the general problem (0.1), (0.2).
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