x1 is of the same rank/generation in hierarchical structure x2 by standard/partial ordering/relationships x3.
Co-workers of approximately equal rank or position (or who share a common jatny'utka via the effectively-same number of intermediate steps), members of the military of the same or analogous rank, actual familial siblings, etc. are included; specification of whether seniority in a given position matters can be made via x3. Not all pairs of subjects can be compared under a given relation, because their hierarchical graphs may be disconnected or there is no clear means by which to map one rank to another. See:"treicu".