Representing relationships with nodesTo allow us to attach properties to instances of relationships, relationships must themselves have a node. In the above diagram, the white circle in between (person) and (eye) is itself a node, and so we're back to being able to represent a relationship with a simple directed graph. We can represent this notationally like this:
Complex relationships How could we model "has zero or more"? One possibility:  This could be represented textually as:
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