This is the maximum interpenetration of yin and yang, this is what ieb = a-1 means (a is the arity, the number of lines in the hexagram).

There is no lattice relationship for /, they are non-comparible under the partial order. However, there are other algebraic properties. This pair (along with /) are mutually opposit for all three forms of opposition: Boolean, linear and trigram. Peace and Separation form the equinox pair in the seasonal cycle, and thus are the mid-points of coherent cyclic waves. In contrast, / are the primary polarization for the dispersed cyclic waves. They form the only dispersed cyclic wave sequence of length 2.