It is shown that certain sum rule identities exist which relate correlation
functions for n Potts spins on the boundary of a planar lattice for n≥4. Explicit expressions of the identities are obtained for n=4,5. It is also
shown that the identities provide the missing link needed for a complete
determination of the duality relation for the n-point correlation function.
The n=4 duality relation is obtained explicitly. More generally we deduce the
number of correlation identities for any n as well as an inversion relation
and a conjecture on the general form of the duality relation.Comment: 11 pages in RevTeX, 4 PS figures, submitted to PR