(self-)connectedness in an object (even a space)
arises when it is the sum of two parts whose interiors have connected complements.
(=> (_Self-Connected ?A ?B) (Exists (?Y ?Z) (And (Object ?Y) (Object ?Z) (Exists (?C) (And (Mereo-Sum ?Y ?Z ?C) (Identity ?A ?C))) (Exists (?D ?E ?F ?G) (And (Interior ?Z ?G) (T-Complement ?G ?F) (Interior ?Y ?E) (T-Complement ?E ?D) (Connected ?D ?F))))))