olemus
liikideks jaotus kontekstist sõltuvas tähenduses

Wiktionary:
the act of forming into a class or classes; a distribution into groups, as classes, orders, families, etc., according to some common relations or attributes

ülevaateid
https://en.wikipedia.org/wiki/Class_(set_theory)

https://www-users.cs.umn.edu/~kumar001/dmbook/ch4.pdf

https://en.wikipedia.org/wiki/Classification

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