Relation _CHANNEL

A channel is the host of an elongate cavity within a (complex) system of fluid circulation. A morphological (and functional) extension is needed for this definition.
Arity: 2
Domain: Material-object
Subrelation-Of: _host
Axioms:
(=> (_Channel ?A ?B)
    (Exists (?Y)
            (And (_Cavity ?Y True)
                 (_Elongate ?Y True)
                 (Host-Of ?A ?Y)
                 (Exists (?Z)
                         (And (_Channel ?Z True) (Connected ?A ?Y))))))