Massive sets produced by semilinear elliptic operators on non-compact Riemann manifolds

One of the origins of the topic of this study is the classification theory of non-compact Riemannian surfaces. It is well known that on parabolic surfaces, any superharmonic functions bounded from below is the identical constant. Hyperbolic surfaces contain nontrivial superharmonic functions. This distinct property of parabolic surfaces form the basis for the definitions of parabolic manifolds with dimensions greater than two.
The classification theory of Riemannian manifolds is directly related to Liouville-type theorems which assert the triviality of bounded solutions of elliptic equations. High efficiency in this topic was shown by the capacitive technique developed in the works of Grigoryan, Losev, Mazepa, and others. In particular, estimates were obtained for the dimensions of bounded harmonic functions and solutions of the stationary Schr?dinger equation on noncompact Riemannian manifolds in terms of massive sets. In this paper, we study the properties of massive sets generated by a semilinear elliptic operator. It was possible to prove that the property of massiveness is preserved under variations of the potential.
The current work generalizes or strengthens the results of Mazepa. A necessary condition for the existence of nontrivial bounded solutions of a semilinear equation is also obtained.