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)))