embership problem for non-linear Abstract Categorial Grammars Sylvain Salvati Abstract In this paper we show that the membership problem for second order nonbstract Categorial Grammars is decidable. A consequence of that result is that Montague-like semantics yield to a decidable text generation problem. Furthermore the proof we propose is based on a new tool, Higher Order Intersection Signatures, which grasps statically dynamic properties of λ-terms and presents an interest in its own.