Derivation of low-temperature expansions for Ising model. VII. The honeycomb-triangular code system

For pt.VI see abstr. A72435 of 1973. It is shown how the principle of complete code balance can be exploited in a systematic way and the method is generalized to apply to partial codes. Euler's law of the edges is used to establish a latent symmetry property of the code system. The new results make possible the derivation of extended series.