[alanbernstein]

Maybe you've encountered it before, but your comment sort of reminds of the concept of a hypergraph (https://en.wikipedia.org/wiki/Hypergraph).

I'm not sure if this is equivalent or related, but I'm imagining an object which can contain, let's call them hypernodes. For example, in the case where A and B mutually imply each other, (A, B) is a hypernode, which internally contains a graph representing the relationship between A and B, but that relationship can be ignored in the main graph. I imagine this would become untenable with a slightly more complex network, though.

[The_rationalist]

A graph whose nodes have for attributes graphs are not an hypergraph. Hypergraph do not modify the definition of a node, only the definition of an (hyper) edge.

From the best AGI project out there: A hypergraph is much like a graph, except that the edges, now called “hyperedges” can contain more than two vertexes. That is, the hyperedge, rather than being an ordered pair of vertexes, is an ordered list of vertexes. The metagraph takes the hypergraph concept one step further: the hyperedge may also contain other hyperedges. https://github.com/opencog/atomspace/blob/master/opencog/she...

[alanbernstein]

Thanks for the clarification, that makes sense. I just would not have been surprised to learn that two different looking extensions of the basic graph concept might turn out to be equivalent, or dual.