> I don't know that you can separate the "all knowledge" graph into 3 layers like this.
The 3 layers mentioned are just the basic structure of ontologies. Concepts eg “vehicle, person, desease, atom, bridge,…” then categories of the concepts, and finally data, ie instances.
Larger knowledge graphs don’t grow by adding more “layers” they add more content to all three layers.
I'm not an expert in this field, but I had never heard of this as a standard ontological structure. I can't find any solid description of it either, are there any references you can share?
I thought that it gets complicated because you can have concepts of concepts, and you can have both categories of concepts and concepts of categories etc etc. It ends up being more than 3 layers, and you get layer violations and loops etc.
The 3 layers mentioned are just the basic structure of ontologies. Concepts eg “vehicle, person, desease, atom, bridge,…” then categories of the concepts, and finally data, ie instances.
Larger knowledge graphs don’t grow by adding more “layers” they add more content to all three layers.