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Nataliya Ilkevych

Publications and source records attributed to Nataliya Ilkevych.

5 recordsLinked to original sources
arXiv2026

An analogue of Koebe's theorem in metric spaces

This paper is devoted to the study of mappings in metric spaces. We investigate mappings satisfying inverse moduli inequalities. We show that under certain conditions on these mappings, their definition domains and the spaces in which they act, the image of a ball under the mappings contains a ball of fixed radius, which corresponds to the statement of the Koebe theorem on one quarter. As consequences, we obtain corresponding results in the Sobolev and Orlicz-Sobolev classes defined in a certain domain of a Riemannian surface or factor space by the group of fractional-linear mappings of the unit ball. We also give consequences for manifolds.

math.CV↗
arXiv2026

On Koebe's theorem for mappings with integral constraints

We study mappings that satisfy the inverse modulus inequality of Poletsky type with respect to $p$-modulus. Given $n-1<p\leqslant n,$ we show that, the image of some ball contains a fixed ball under mappings mentioned above. This statement can be interpreted as the well-known analogue of Koebe's theorem for analytic functions. As a consequence, we obtain the openness and discreteness of the limit mapping in the class under study. The paper also studies mappings of the Orlicz-Sobolev classes, for which an analogue of the Koebe one-quarter theorem is obtained as a consequence of the main results

math.CV↗
arXiv2024

On the lower bounds of $p$-modulus of families of paths and a finite connectedness

We study the problem of the lower bounds of the modulus of families of paths of order $p,$ $p>n-1,$ and their connection with the geometry of domains containing the specified families. Among other things, we have proved an analogue of Näkki's theorem on the positivity of the $p$-module of families of paths joining a pair of continua in the given domain. The geometry of domains with a strongly accessible boundary in the sense of the $p$-modulus of families of paths was also studied. We show that domains with a $p$-strongly accessible boundary with respect to a $p$-modulus, $p>n-1,$ are are finitely connected at their boundary. The mentioned result generalizes Näkki's result, which was proved for uniform domains in the case of a conformal modulus.

math.CV↗
arXiv2024

On lower distance estimates of mappings in metric spaces

We consider mappings satisfying an upper bound for the distortion of families of curves. We establish lower bounds for the distortion of distances under such mappings. As applications, we obtain theorems on the discreteness of the limit mapping of a sequence of mappings converging locally uniformly. We separately consider cases when mappings are defined in Euclidean $n$-dimensional space and in a metric space.

math.CV↗