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Marko Slapar

Publications and source records attributed to Marko Slapar.

15 recordsLinked to original sources
arXiv2026

Degree-Bounded Polynomial Convexity of Circular and Smooth Arcs

Let $d\ge 1$ be an integer. We study $d$-polynomial convexity of smooth Jordan arcs in terms of their total absolute curvature $\T(K)$. We prove that every $\cC^2$-smooth Jordan arc $K\subset\C$ satisfying $\T(K)\le \frac{d-1}{d}\pi$ is $d$-polynomially convex. This bound is sharp: for every $\tau>\frac{d-1}{d}\pi$, there exists a smooth Jordan arc $K\subset\C$ such that $\T(K)<\tau$ and $K$ is not $d$-polynomially convex. We also show that, for $0<\alpha<\pi$, the circular arc $A_\alpha=\{e^{it}:|t|\le \alpha\}$ is $d$-polynomially convex if and only if $\alpha\le \frac{d-1}{d}\pi$.

math.CV↗
arXiv2026

Cancelling CR singularities of 3-manifolds in complex threefolds

Let $M$ be a closed oriented $3$-manifold generically embedded in a complex $3$-manifold $X$. Its CR singular set is an oriented link $L\subset M$. We prove that if a sublink $L'\subset L$ bounds an oriented Seifert surface $S\subset M$ in the complement of $L\setminus L'$, then the CR singularities along $L'$ can be cancelled by an arbitrarily $\mathcal C^0$-small isotopy supported in an arbitrarily small neighbourhood of $S$.

math.GT↗
arXiv2024

Polynomial convexity with degree bounds

We introduce different notions of polynomial convexity with bounds on degrees of polynomials in $\mathbb C^n$. We provide some examples in higher dimensions and show necessary and sufficient conditions for polynomial convexity with degree bounds for certain sets of points in $\mathbb C$ and for certain arcs in the unit circle.

math.CV↗
arXiv2021

On the Thom conjecture in $CP^3$

What is the simplest smooth simply connected 4-manifold embedded in $CP^3$ homologous to a degree $d$ hypersurface $V_d$? A version of this question associated with Thom asks if $V_d$ has the smallest $b_2$ among all such manifolds. While this is true for degree at most $4$, we show that for all $d \geq 5$, there is a manifold $M_d$ in this homology class with $b_2(M_d) < b_2(V_d)$. This contrasts with the Kronheimer-Mrowka solution of the Thom conjecture about surfaces in $CP^2$, and is similar to results of Freedman for $2n$-manifolds in $CP^{n+1}$ with $n$ odd and greater than $1$.

math.GT↗
arXiv2018

Proper holomorphic curves attached to domains

Let D be a domain in C^n with smooth boundary, of finite 1-type at a point p in the boundary and such that the closure of D has a basis of Stein Runge neighborhoods. Assume that there exists an analytic disc which intersects the closure of D exactly at p. We construct proper holomorphic maps from any open Riemann surface S which are attached to the closure of D exactly at p.

math.CV↗
arXiv2017

On Normal Forms of Complex Points of codimension 2 submanifolds

In this paper we present some linear algebra behind quadratic parts of quadratically flat complex points of codimension two real submanifold in a complex manifold. Assuming some extra nondegenericity and using the result of Hong, complete normal form descriptions can be given, and in low dimensions, we obtain a complete classification without any extra assumptions.

math.CV↗
arXiv2016

Existence results of totally real immersions and embeddings into $\mathbb{C}^N$

We prove that the existence of totally real immersions of manifolds is a closed property under cut-and-paste constructions along submanifolds including connected sums. We study the existence of totally real embeddings for simply connected 5-manifolds and orientable 6-manifolds and determine the diffeomorphism and homotopy types. We show that the fundamental group is not an obstruction for the existence of a totally real embedding for high-dimensional manifolds in contrast with the situation in dimension four.

math.CV↗
arXiv2013

On complex points of codimension 2 submanifolds

In this paper we study the structure of complex points of codimension 2 real submanifolds in complex $n$ dimensional manifolds. We show that the local structure of a complex point up to isotopy only depends on their type (either elliptic or hyperbolic). We also show that any such submanifold can be smoothly isotoped into a submanifold that has 2-strictly pseudoconvex neighborhood basis.

math.CV↗
arXiv2011

Modeling complex points up to isotopy

In this paper we examine the structure of complex points of real 4-manifolds embedded into complex 3-manifolds up to isotopy. We show that there are only two types of complex points up to isotopy and as a consequence, show that any such embedding can be deformed by isotopy to a manifold having 2-complete neighborhood basis.

math.CV↗
arXiv2011

The generalized Oka-Grauert principle for 1-convex manifolds

This paper presents a proof of the generalized Oka-Grauert principle for 1-convex manifolds: Every continuous mapping from a 1-convex manifold X to a complex manifold Y which is already holomorphic on a neighborhood of the exceptional set is homotopic to a holomorphic one provided that either Y satisfies CAP or we are free to change the complex structure on X.

math.CV↗
arXiv2007

Stein structures and holomorphic mappings

We prove that every continuous map from a Stein manifold X to a complex manifold Y can be made holomorphic by a homotopic deformation of both the map and the Stein structure on X. In the absence of topological obstructions the holomorphic map may be chosen to have pointwise maximal rank. The analogous result holds for any compact Hausdorff family of maps, but it fails in general for a noncompact family. Our main results are actually proved for smooth almost complex source manifolds (X,J) with the correct handlebody structure. The paper contains another proof of Eliashberg's (Int J Math 1:29--46, 1990) homotopy characterization of Stein manifolds and a slightly different explanation of the construction of exotic Stein surfaces due to Gompf (Ann Math 148 (2):619--693, 1998; J Symplectic Geom 3:565--587, 2005). (See also the related preprint math/0509419).

math.CV↗
arXiv2006

Deformations of Stein structures and extensions of holomorphic mappings

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 X (and of its smooth structure when X is a Stein surface)we find a holomorphic map from X to Y which agrees with f on A and which is homotopic to f relative to A. The analogous results in the case when the variety A is empty have been obtained in the preprint math.CV/0507212.

math.CV↗
arXiv2003

On Stein Neighborhood Basis of Real Surfaces

In this paper, we show that a compact real surface embedded in a complex surface has a regular Stein neighborhood basis, provided that there are only finitely many complex points on the surface, and that they are all flat and hyperbolic. An application to unions of totally real planes in $\CC^2$ is then given.

math.CV↗
arXiv2003

Real Surfaces in Elliptic Surfaces

We study the structure of complex points on real surfaces, embedded into complex Elliptic surfaces. We show, for example, that any compact surface has a totally real embedding into a blow-up of a K3 surface. We also exhibit smooth disc bundles over compact orientable surfaces that have a Stein structure as Stein domains inside Elliptic surfaces.

math.CV↗