  The spacetime short-distance structure at the Planck scale is governed by the
Planck length, usually interpreted as a three-dimensional Euclidian length. As
such, it is not Lorentz invariant and clashes with Einstein's special
relativity, which is thus unable to describe the Planck scale kinematics. The
solution to this problem is twofold. First, one has to re-interpret the Planck
length as a Lorentz invariant four-dimensional pseudo-length. Second, to comply
with a non-vanishing cosmological term~$\Lambda$, one has to replace the
standard Poincar\'e-invariant special relativity with the de Sitter-invariant
special relativity. Since the Planck pseudo-length does not clash with the de
Sitter-invariant special relativity, it provides a consistent description of
the Planck scale kinematics in the presence of~$\Lambda$. Under the above
replacement, general relativity changes to the de Sitter-invariant general
relativity, in which~$\Lambda$ is constitutive. In this paper, the ensuing
Friedmann equations are derived, and some implications for cosmology are
explored and discussed.
