Hi!
As far as I can understand then ConceptNode is used for the defintion of the concept/class? How can I express that some Node is the instance of this class? I guess that notion of instance is different from the set memebrship?
My understanding is that Atomspace is very flexible regarding instance/class relationship - i.e. some concept of class can be instance of the higher order class (like there object, class, meta-class in Model Driven Development).