2.5 Stand-alone relations
While it is possible for concepts not to have any arcs attached to themselves, this is not possible for relations. A relation must have at least one arc that belongs to it.
For example, the following is not a well-formed conceptual graph:
(On) Ill-formed conceptual graph
However, the following is a well-formed conceptual graph, since the relation (In) has at least one arc that belongs to it (in fact, it has two):
[Bird]->(In)->[SycamoreTree] Well-formed conceptual graph
It means "There is a bird in a sycamore tree".
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