Sorry if this was already discussed, but I found the
approach proposed by Giancarlo Guizzardi, very interesting.
He explores the ontological meta-property called "rigidity"
for providing an ontological foundation for his approach.
His approach can be found
here.
"Agent Roles, Qua Individuals and The Counting Problem"
His approach was included in the so called Unified
Foundational Ontology (UFO), which is presented
here.
"Ontological foundations for strcutural conceptual
models"
Best regards.
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