  We construct the complete set of metric-configuration solutions of the
ghost-free massive bigravity for the scenario in which the g-metric is the
Friedmann-Lemaitre-Robertson-Walker (FLRW) one, and the interaction Lagrangian
between the two metrics contributes an effective ideal fluid energy-momentum
tensor to the g-metric equations. This set corresponds to the exact background
cosmological solution space of the theory.
