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In this paper we introduce the notion of a formal complex contact structure on an odd dimensional complex manifold. Our main result is that every formal complex contact structure on a Stein manifold $X$ is homotopic to a holomorphic contact…

Complex Variables · Mathematics 2020-10-27 Franc Forstneric

This expository paper is concerned with the properties of proper holomorphic mappings between domains in complex affine spaces. We discuss some of the main geometric methods of this theory, such as the Reflection Principle, the scaling…

Complex Variables · Mathematics 2017-03-22 Sergey Pinchuk , Rasul Shafikov , Alexandre Sukhov

Given a Stein manifold with the density property, we show that under a suitable topological condition it is possible to prescribe derivatives at a finite number of points to automorphisms depending holomorphically on a Stein parameter. This…

Complex Variables · Mathematics 2020-11-12 Alexandre Ramos-Peon , Riccardo Ugolini

It is an elementary fact that the action by holomorphic automorphisms on C^n is infinitely transitive, i.e., m-transitive for any m in N. The same holds on any Stein manifold with the holomorphic density property X. We study a parametrized…

Complex Variables · Mathematics 2015-11-03 Frank Kutzschebauch , Alexandre Ramos-Peon

We prove that the classical Oka property of a complex manifold Y, concerning the existence and homotopy classification of holomorphic mappings from Stein manifolds to Y, is equivalent to a Runge approximation property for holomorphic maps…

Complex Variables · Mathematics 2007-05-23 Franc Forstneric

Let X be a Stein manifold, A a closed complex subvariety of X, and f a continuous map from X to a complex manifold Y whose restriction to A is holomorphic. After a homotopic deformation of the Stein structure outside a neighborhood of A in…

Complex Variables · Mathematics 2007-08-16 Franc Forstneric , Marko Slapar

Let $(E,h)$ be a semipositive hermitian holomorphic line bundle on a compact complex manifold $X$ with $\dim X>1$. Assume that for each point $x\in X$ there exists a divisor $D\in |E|$ in the complete linear system determined by $E$ whose…

Complex Variables · Mathematics 2025-04-10 Franc Forstneric , Yuta Kusakabe

In this paper we present the main developments in Oka theory since the publication of my book Stein Manifolds and Holomorphic Mappings (The Homotopy Principle in Complex Analysis)}, Second Edition, Springer, 2017. We also give several new…

Complex Variables · Mathematics 2023-02-21 Franc Forstneric

In a previous work, the authors introduced the notion of `coherent tangent bundle', which is useful for giving a treatment of singularities of smooth maps without ambient spaces. Two different types of Gauss-Bonnet formulas on coherent…

Differential Geometry · Mathematics 2015-07-10 Kentaro Saji , Masaaki Umehara , Kotaro Yamada

Suppose that Y is a complex manifold with the property that any holomorphic map from a compact convex set in a complex Euclidean space C^n (for any n) to Y is a uniform limit of entire maps from C^n to Y. We prove that a holomorphic map…

Complex Variables · Mathematics 2007-05-23 Franc Forstneric

We prove the parametric homotopy principle for holomorphic immersions of Stein manifolds into Euclidian space and the homotopy principle with approximation on holomorphically convex sets. We write an integration by parts like formula for…

Complex Variables · Mathematics 2010-07-27 Dejan Kolarič

In this text we expose basic cases of some fundamental ideas and methods of topology. Namely, of homotopy, degree, fundamental group, covering, Whitehead invariant, etc. This is done by considering the elementary example: closed polygonal…

History and Overview · Mathematics 2026-05-07 E. Alkin , O. Nikitenko , A. Skopenkov

In this note, we show that the homotopy type of a complex manifold X satisfying the Oka property is captured by holomorphic maps from the affine spaces C^n, n\geq 0, into X. Among such X are all complex Lie groups and their homogeneous…

Complex Variables · Mathematics 2009-07-27 Finnur Larusson

We prove a homotopy theorem for sheaves. Its application shortens and simplifies the proof of many Oka principles such as Gromov's Oka principle for elliptic submersions.

Complex Variables · Mathematics 2018-12-05 Luca Studer

Let $X$ be an open Riemann surface. We prove an Oka property on the approximation and interpolation of continuous maps $X \to (\mathbb{C}^*)^2$ by proper holomorphic embeddings, provided that we permit a smooth deformation of the complex…

Complex Variables · Mathematics 2014-05-07 Tyson Ritter

Let $G$ be a reductive complex Lie group acting holomorphically on normal Stein spaces $X$ and $Y$, which are locally $G$-biholomorphic over a common categorical quotient $Q$. When is there a global $G$-biholomorphism $X\to Y$? If the…

Complex Variables · Mathematics 2013-08-15 Frank Kutzschebauch , Finnur Larusson , Gerald W. Schwarz

We will prove the relative homotopy principle for smooth maps with singularities of a given {\cal K}-invariant class with a mild condition. We next study a filtration of the group of homotopy self-equivalences of a given manifold P by…

Geometric Topology · Mathematics 2007-05-23 Yoshifumi Ando

This is the second in a series of papers. Here we develop here an intersection theory for manifolds equipped with an action of a finite group. As in our previous paper, our approach will be homotopy theoretic, enabling us to circumvent the…

Algebraic Topology · Mathematics 2009-01-23 John R. Klein , Bruce Williams

In this paper we study cobordism categories consisting of manifolds which are endowed with geometric structure. Examples of such geometric structures include symplectic structures, flat connections on principal bundles, and complex…

Algebraic Topology · Mathematics 2009-06-11 David Ayala

Given a compact K\"ahler manifold, Geometric Invariant Theory is applied to construct analytic GIT-quotients that are local models for a classifying space of (poly)stable holomorphic vector bundles containing the coarse moduli space of…

Complex Variables · Mathematics 2021-04-07 Nicholas Buchdahl , Georg Schumacher