An aggregate is lumpy when some parts are atoms, and some parts are continuous aggregates, ie, x has some part y, all of whose parts z have at least one proper part w.
(<=> (_Lumpy ?A ?B)
(And (Exists (?X) (And (_Atom ?X True) (Part-Of ?X ?A)))
(Exists (?Y)
(And (Part-Of ?Y ?A)
(Forall (?Z)
(=> (Part-Of ?B ?Y)
(Exists (?W)
(Proper-Part-Of ?W ?B))))))
(Mereological-Property ?A ?B)))