Abstract: We consider a nonlinear Robin problem driven by the $(p,q)$-Laplacian plus an indefinite potential term and with a parametric reaction term. Under minimal conditions on the reaction function, which concern only its behavior near zero, we show that, for all $\lambda >0$ small, the problem has a nodal solution $y_{\lambda} \in C^1(\bar{Ω})$ and we have $y_{\lambda} \rightarrow 0$ in $C^1(\bar{Ω})$ as $\lambda \rightarrow 0^+$.

Key words: (p, q)-Laplacian, indefinite potential, nonlinear regularity, extremal constant sign solutions, nodal solutions