Hierarchical relations or hierarchical class memberships have the same diode-like quality of frames of comparison, but the combinatorially entailed relations differ because the hierarchical relation itself is the basis for a frame of coordination. For example, if Tom is the father of Simon and Jane, then Simon and Jane are known to be siblings. If Tom is taller than both Simon and Jane, however, the relative heights of Simon and Jane are unknown. Hierarchical relations are essential to many forms of verbal abstraction.
