On Kasner solution in Bianchi I f(T) cosmology

Recently the cosmological dynamics of an anisotropic Universe in f(T) gravity became an area of intense investigations. Some earlier papers devoted to this issue contain contradictory claims about the nature and properties of vacuum solutions in this theory. The goal of the present paper is to clarify this situation. We compare properties of f(T) and f(R) vacuum solutions and outline differences between them. The Kasner solution appears to be an exact solution for the T = 0 branch, and an asymptotic solution for the T ≠ 0 branch. It is shown that the Kasner solution is a past attractor if T < 0, being a past and future attractor for the T > 0 branch. (orig.)