arXiv subjects

N. Kopteva

Publications and source records attributed to N. Kopteva.

3 recordsLinked to original sources

arXiv2011

Full analysis of the Green's function for a singularly perturbed convection-diffusion problem in three dimensions

A linear singularly perturbed convection-diffusion problem with characteristic layers is considered in three dimensions. Sharp bounds for the associated Green's function and its derivatives are established in the $L_1$ norm. The dependence of these bounds on the small perturbation parameter is shown explicitly. The obtained estimates will be used in a forthcoming numerical analysis of the considered problem. The present article is a more detailed version of our recent paper [7].

math.NA↗

arXiv2005

Discrete RP groups with a parabolic generator

We deal with two-generator subgroups of PSL(2,C) with real traces of both generators and their commutator. We give discreteness criteria for these groups when at least one of the generators is parabolic. We also present a list of the corresponding orbifolds.

math.GR↗

arXiv2005

All discrete RP groups with non-$π$-loxodromic generators

In this paper we give necessary and sufficient conditions for discreteness of a group generated by a hyperbolic element and an elliptic one of odd order. This completes the classification of discrete groups with non-$π$-loxodromic generators in the class of two-generator groups with real parameters. The criterion is given also as a list of all parameters that correspond to discrete groups. An interesting corollary of the result is that the group of the minimal known volume hyperbolic orbifold has real parameters.

math.GR↗