Abstract:
We give an example of an infinitesimally nonrigid polyhedron in the Lobachevskiĭ 3-space and construct an infinitesimal flex of that polyhedron such that the volume of the polyhedron is not stationary under the flex.
Keywords:infinitesimally nonrigid polyhedron, Lobachevskiĭ space, hyperbolic space, volume, total mean curvature, infinitesimal flex, Schläfli formula.