arXiv subjects
Publications and source records attributed to L. Baracco.
We give positive answer to a conjecture by Agranovsky. A continuous function on the sphere which has separate holomorphic extension along the set of complex lines passing through three non aligned interior points, is the trace of a holomorphic function in the ball.
Real analytic functions on the boundary of the sphere which have separate holomorphic extension along the complex lines through a boundary point have holomorphic extension to the ball. This was proved in a previous preprint by an argument of CR geometry. We give here an elementary proof based on the expansion in holomorphic and antiholomorphic powers.
We discuss a general result of holomorphic extension of a real analytic function $f$ defined on the boundary $\partial D$ of a real analytic strictly convex subset $D\subset\subset \C^n$. We show that this follows from the hypothesis of separate holomorphic extension along stationary/extremal discs.
In $\C^2=\R^2+i\R^2$ with coordinates $z=(z_1,z_2), z=x+iy$, we consider a function $f$ continuous on a domain $Ω$ of $\R^2$ separately real analytic in $x_1$ and CR extendible to $y_2$ (resp. CR extendible to $y_2>0$). This means that $f(\cdot,x_2)$ extends holomorphically for $|y_1|<ε_{x_2}$ and $f(x_1,\cdot)$ for $| y_2|<ε$ (resp. $0\leq y_2<ε$ continuous up to $y_2=0$) with $ε$ independent of $x_1$. We prove in Theorem 3.4 that $f$ is then real analytic (resp. in Theorem 3.5 that it extends holomorphically to a "wedge" $W= Ω+iΓ_ε$ where $Γ_ε$ is an open cone trumcated by $|y|<ε$ and containing the ray $0<y_2<ε)$.
We prove non-subelliptic estimates for the tangential Cauchy-Riemann system over a weakly "$q$-pseudoconvex" higher codimensional submanifold $M$ of $\C^n$. Let us point out that our hypotheses do not suffice to guarantee subelliptic estimates, in general. Even more: hypoellipticity of the tangential C-R system is not in question (as shows the example by Kohn in case of a Levi-flat hypersurface). However our estimates suffice for existence of smooth solutions to the inhomogeneous C-R equations in certain degree. The main ingredients in our proofs are the weighted $L^2$ estimates by Hörmander and Kohn and the tangential $\bar\partial$-Neumann operator by Kohn. As for the notion of $q$ pseudoconvexity we follow closely Zampieri. The main technical result is a version for "perturbed" $q$-pseudoconvex domains of a similar result by Ahn who generalizes in turn Chen-Shaw.
The goal of this paper is twofold. First, to give purely local boundary uniqueness results for maps defined only on one side as germs at a boundary point and hence not necessarily sending any domain to itself and also under the weaker assumption that $f(z)=z+o(|z-p|^3)$ holds only for $z$ in a proper cone in $D$ with vertex $p$. Such results have no analogues in one complex variable in contrast to the situation when a domain is preserved. And second, to extend the above results from boundaries of domains to submanifolds of higher codimension.