On Gehring-Martin-Tan groups with an elliptic generatorRepovš, Dušan (Avtor) Vesnin, Andreî Jurʹevič (Avtor) hyperbolic orbifolddiscreteness conditiontwo-generated groupThe Gehring-Martin-Tan inequality for two-generator subgroups of ▫$\text{PSL}(2,\mathbb{C})$▫ is one of the best known discreteness conditions. A Kleinian group ▫$G$▫ is called a Gehring-Martin-Tan group if the equality holds for the group ▫$G$▫. We give a method for constructing Gehring-Martin-Tan groups with a generator of order four and present some examples. These groups arise as groups of finite-volume hyperbolic 3-orbifolds.20162019-09-24 12:47:50Članek v reviji111110sl