  The spin-orbital model for triply degenerate t_2g electrons on a triangular
lattice has been shown to be dominated by dimers: the phase diagram contains
both strongly resonating, compound spin-orbital dimer states and quasi-static,
spin-singlet valence-bond (VB) states. To elucidate the nature of the true
ground state in these different regimes, the model is mapped to a number of
quantum dimer models (QDMs), each of which has three dimer colors. The generic
multicolored QDM, illustrated for the two- and three-color cases, possesses a
topological color structure, "color vison" excitations, and broad regions of
resonating VB phases. The specific models are analyzed to gain further insight
into the likely ground states in the superexchange and direct-exchange limits
of the electronic Hamiltonian, and suggest a strong tendency towards VB order
in all cases.
