  An analysis of the dynamics is performed, of exactly solvable models for
fragile and strong glasses, exploiting the partitioning of the free energy
landscape in inherent structures. The results are compared with the exact
solution of the dynamics, by employing the formulation of an effective
temperature used in literature. Also a new formulation is introduced, based
upon general statistical considerations, that performs better. Though the
considered models are conceptually simple there is no limit in which the
inherent structure approach is exact.
