NON-VANISHING FOR GROUP LP-COHOMOLOGY OF SOLVABLE AND SEMISIMPLE LIE GROUPS

We obtain non-vanishing of group Lp-cohomology of Lie groups for p large and when the degree is equal to the rank of the group. This applies both to semisimple and to some suitable solvable groups. In particular, it confirms that Gromov's question on vanishing below the rank is formulated optimally. To achieve this, some complementary vanishings are combined with the use of spectral sequences. To deduce the semisimple case from the solvable one, we also need comparison results between various theories for Lp-cohomology, allowing the use of quasi-isometry invariance.