  The superintegrable chiral Potts model has many resemblances to the Ising
model, so it is natural to look for algebraic properties similar to those found
for the Ising model by Onsager, Kaufman and Yang. The spontaneous magnetization
M_r can be written in terms of a sum over the elements of a matrix S_r. The
author conjectured the form of the elements, and this conjecture has been
verified by Iorgov et al. The author also conjectured in 2008 that this sum
could be expressed as a determinant, and has recently evaluated the determinant
to obtain the known result for M_r. Here we prove that the sum and the
determinant are indeed identical expressions.
