Tower multitype and global regularity of the -Neumann operator

A new approach is given to property (Pq) defined by Catlin for q=1 in a global and by Sibony in a local context, subsequently extended by Fu-Straube for q>1. This property is known to imply compactness and global regularity in the -Neumann problem by a result of Kohn-Nirenberg, as well as condition R by a result of Bell-Ligocka. In particular, we provide a self-contained proof of property (Pq) for pseudoconvex hypersurfaces of finite D'Angelo q-type, the case originally studied by Catlin. Moreover, our proof covers more general classes of hypersurfaces inspired by a recent work of Huang-Yin. Proofs are broken down into isolated steps, some of which do not require pseudoconvexity. Our tools include: a new multitype invariant based on distinguished nested sequences of (1, 0) subbundles, defined in terms of derivatives of the Levi form; real and complex formal orbits; k-jets of functions relative to pairs of formal submanifolds; relative contact orders generalizing the usual contact orders; a new notion of supertangent vector fields having higher than expected relative contact orders; and a formal variant of a result by Diederich-Forn ss arising as a key step in their proof of Kohn's ideal termination in the real-analytic case.