Relation _OPENING

An opening is a hole which connects two holes within two distinct objects; eg, in anatomy, it can exist by default in the organism or there can be another object regulating its existence in time (eg, pilorum, glottis).
Arity: 2
Subrelation-Of: _hole
Axioms:
(=> (_Opening ?A ?B)
    (Exists (?X ?Y ?Z ?W)
            (And (Hole-In ?X ?Z)
                 (Hole-In ?Y ?W)
                 (Different ?Z ?W)
                 (Connects ?A ?X ?Y))))