On the degenerations of solvable Leibniz algebras

The present paper is devoted to the description of rigid solvable Leibniz algebras. In particular, we prove that solvable Leibniz algebras under some conditions on the nilradical are rigid and we describe four-dimensional solvable Leibniz algebras with three-dimensional rigid nilradical. We show that the Grunewald–O’Halloran’s conjecture “any n-dimensional nilpotent Lie algebra is a degeneration of some algebra of the same dimension” holds for Leibniz algebras of dimensions less than four. The algebra of level one, which is omitted in the 1991 Gorbatsevich’s paper, is indicated.