“…Q-homeomorphisms are closely connected with mappings that generate bounded composition operators on Sobolev spaces (p, q-quasiconformal mappings) [12,36,47,48] which were studied on Carnot groups in [39,40,47,49]. In the recent decade the geometric theory of composition operators on Sobolev spaces was applied to spectral estimates of the Laplace operator in Euclidean non-convex domains (see, for example, [5,6,11,13,15,16]) and so results of this article have applications to the Sobolev mappings theory, to the spectral theory of (sub)elliptic operators and to the non-linear elasticity problems associated with vector fields that satisfy Hörmander's hypoellipticity condition.…”