> Link type: The relationships between object types, supporting 1-to-1, 1-to-many, and many-to-many relationships.
Seems incredibly naive in terms of symbolic representation of knowledge. Maybe I spent too much time with OWL.
OWL 1, for example, has stuff like transitive properties (the classical example is A ancestorOf B, B ancestorOf C, therefore I can infer A ancestorOf C if I annotate ancestorOf as a transitive property).
Union, equivalence, inversion, symmetries, cardinality. Those are all possible to represent symbolic in OWL ontologies.
They're also neatly separated in different types (OWL Lite, OWL DL, OWL Full). OWL Lite and DL for example are proven to be decidable (you won't get some halt when doing inference, no matter what).
I know there are plenty of database engines to store triples and graphs, and plenty of reasoners out there.
I haven't studied OWL 2 yet or newer stuff like SHACL, but I know it's supposed to be even better.