It is shown that if a point x 0 ∊ ℝn, n ≥ 3, is an essential isolated singularity of an open discrete Q-mapping f : D → \( \overline {\mathbb {R}^n} \), B f is the set of branch points of f in D; and a point z 0 ∊ \( \overline {\mathbb {R}^n} \) is an asymptotic limit of f at the point x 0; then, for any neighborhood U containing the point x 0; the point z 0 ∊ \( \overline {f\left( {B_f \cap U} \right)} \) provided that the function Q has either a finite mean oscillation at the point x 0 or a logarithmic singularity whose order does not exceed n − 1: Moreover, for n ≥ 2; under the indicated conditions imposed on the function Q; every point of the set \( \overline {\mathbb {R}^n} \)\ f(D) is an asymptotic limit of f at the point x 0. For n ≥ 3, the following relation is true: \( \overline {\mathbb{R}^n } \backslash f\left( D \right) \subset \overline {f\,B_f } \) . In addition, if \( \infty \notin f\left( D \right) \), then the set f B f is infinite and \( x_0 \in \overline {B_f } \).
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Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 62, No. 2, pp. 215–230, February, 2010.
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Sevost’yanov, E.A. On the sets of branch points of mappings more general than quasiregular. Ukr Math J 62, 241–258 (2010). https://doi.org/10.1007/s11253-010-0348-0
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DOI: https://doi.org/10.1007/s11253-010-0348-0