  Resonating valence bond (RVB) liquids in two dimensions are believed to
exhibit topological order and to admit no local order parameter of any kind.
This is a defining property of "liquids" but it has been explicitly confirmed
only in a few exactly solvable models. In this paper, we investigate the
quantum dimer model on the triangular lattice. It possesses an RVB-type liquid
phase, however, for which the absence of a local order parameter has not been
proved. We examine the question numerically with a measure based on reduced
density matrices. We find a scaling of the measure which strongly supports the
absence of any local order parameter.
