  We consider triangular holes on the hexagonal lattice and we study their
interaction when the rest of the lattice is covered by dimers. More precisely,
we analyze the joint correlation of these triangular holes in a ``sea'' of
dimers. We determine the asymptotics of the joint correlation (for large
separations between the holes) in the case when one of the holes has side 1,
all remaining holes have side 2, and the holes are distributed symmetrically
with respect to a symmetry axis. Our result has a striking physical
interpretation. If we regard the holes as electrical charges, with charge equal
to the difference between the number of down-pointing and up-pointing unit
triangles in a hole, the logarithm of the joint correlation behaves exactly
like the electrostatic potential energy of this two-dimensional electrostatic
system: it is obtained by a Superposition Principle from the interaction of all
pairs, and the pair interactions are according to Coulomb's law.
