#trilogy  a set of three literary or dramatic works related in subject or theme
  supertype:  triad__trio__triplet  a set of three similar things considered as a unit
     supertype:  set.aggregation  a group of things of the same kind that belong together and are so used: "a set of books"; "a set of golf clubs"; "a set of teeth"
        supertype:  aggregation__collection__accumulation__assemblage  several things grouped together
           supertype:  group__grouping  any number of entities (members) considered as a unit
              supertype:  collection  something gathering separated things (entities/situations)
                 supertype:  divisible_entity__divisibleentity  many classifications under this category are application-dependant
                    supertype:  entity  something that can be "involved" in a situation
                       supertype:  thing__something___T__t___3D_or_4D_thing_or_anything_else  any category (type or individual) is instance of this type; any type is also a subtype of this type
                    supertype:  divisible_thing__divisiblething
                       supertype:  thing__something___T__t___3D_or_4D_thing_or_anything_else  any category (type or individual) is instance of this type; any type is also a subtype of this type

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