Let$X$be a complex manifold with finitely many ends such that each end is either$q$-concave or ($n−q$)-convex. If $$q< \tfrac{1}{2}n$$ , then we prove that$H$^{p$n−q$}$(X)$is Hausdorff for all$p$. This is not true in general if $$q \geqslant \tfrac{1}{2}n$$ (Rossi’s example with$n$=2 and$q$=1). If all ends are$q$-concave, then this is the classical Andreotti-Vesentini separation theorem (and holds also for $$q \geqslant \tfrac{1}{2}n$$ ). Moreover the result was already known in the case when the$q$-concave ends can be ‘filled in’ (again also for $$q \geqslant \tfrac{1}{2}n$$ ). To prove the result we first have to study Serre duality for the case of more general families of supports (instead of the family of all closed sets and the family of all compact sets) which is the main part of the paper. At the end we give an application to the extensibility of CR-forms of bidegree ($p, q$) from ($n−q$)-convex boundaries, $$q< \tfrac{1}{2}n$$ .

We give interior estimates for first derivatives of solutions to a type of complex Monge-Ampère equations in convex domains. We also show global estimates for first derivatives of solutions in arbitrary domains. These global estimates are then used to show interior regularity of solutions to the complex Monge-Ampère equations in hyperconvex domains having a bounded exhaustion function which is globally Lipschitz. Finally we give examples of domains which have such an exhaustion function and domains which do not.

We investigate a problem of approximation of a large class of nonlinear expressions$f$($x, u$, ∇$u$), including polyconvex functions. Here$u$: Ω→$R$^{$m$}, Ω⊂$R$^{$n$}, is a mapping from the Sobolev space$W$^{$1,p$}. In particular, when$p=n$, we obtain the approximation by mappings which are continuous, differentiable a.e. and, if in addition$n=m$, satisfy the Luzin condition. From the point of view of applications such mappings are almost as good as Lipschitz mappings. As far as we know, for the nonlinear problems that we consider, no natural approximation results were known so far. The results about the approximation of$f$($x, u$, ∇$u$) are consequences of the main result of the paper, Theorem 1.3, on a very strong approximation of Sobolev functions by locally weakly monotone functions.

We study the dynamics of polynomial automorphisms of$C$^{$k$}. To an algebraically stable automorphism we associate positive closed currents which are invariant under$f$, considering$f$as a rational map on$P$^{$k$}. These currents give information on the dynamics and allow us to construct a canonical invariant measure which is shown to be mixing.

We prove a theorem on non-existence of lacunas of the fundamental solution for hyperbolic differential operators with constant coefficients.