sumo#class__clas  classes differ from sets in three important respects: 1) classes are not assumed to be extensional, i.e. distinct classes might well have exactly the same instances, 2) classes typically have an associated `condition' that determines the instances of the class, e.g., the condition `human' determines the "class of humans" (note that some classes might satisfy their own condition (e.g., the "class of abstract things" is "abstract") and hence be instances of themselves), 3) the instances of a class may occur only once within the class, i.e. a class cannot contain duplicate instances
  closed_exclusion:  set
  subtype:  datatype  restriction  all_different (pm)  deprecated_class  rigid  leaf_type  non-empty  situation_class  attribute_class  substance_class  virtual_class
  instance:  class_of_inheritable_relation_type (pm)  thing (pm)  nothing (pm)
  supertype:  class__clas  rdfs#class has pm#binary_relation_type as instance and hence is different from sumo#class
     supertype:  type  second-order type or more
        supertype:  non_spatial_collection__nonspatialcollection__true_collection  something gathering separated things (entities/situations) and that is not a spatial object
           supertype:  non_spatial_object_that_is_not_an_attribute_or_quality_or_measure
              supertype:  non_spatial_object__nonspatialobject  abstraction or description content/medium/container (a description medium that has some spatial feature is both instance of sumo#object and pm#non_spatial_object
                 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:  intangible  The collection of things that are not physical -- are not made of, or encoded in, matter. Every cyc#Collection is a cyc#intangible (even if its instances are tangible), and so are some cyc#individuals.  Caution: do not confuse `tangibility' with `perceivability' -- humans can perceive light even though it's intangible--at least in a sense.
                    supertype:  partially_intangible__partiallyintangible  The collection of things that either are wholly intangible (see cyc#Intangible) or have at least one intangible (i.e. immaterial) part (see cyc#intangibleParts). This includes intangible individuals, such as instances of cyc#Number-General  or cyc#Agreement, as well as non-individuals (all of which are intangible), i.e. instances of cyc#SetOrCollection.  It also includes things that have both tangible and intangible components (see cyc#CompositeTangibleAndIntangibleObject),  such as a printed copy of a newspaper (as its information content is intangible) or a person (as her mental states are intangible).
                       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:  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:  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
        supertype:  abstract__entity_without_spatial_feature  e.g., knowledge, motivation, measure; properties or qualities as distinguished from any particular embodiment of the properties/qualities in a physical medium; instances of sumo#abstract can be said to exist in the same sense as mathematical objects such as sets and relations, but they cannot exist at a particular place or time without some physical encoding or embodiment
           supertype:  non_spatial_object__nonspatialobject  abstraction or description content/medium/container (a description medium that has some spatial feature is both instance of sumo#object and pm#non_spatial_object
     supertype:  set_or_class  like sumo#set_or_class but including rdfs#class too
        supertype:  non_spatial_collection__nonspatialcollection__true_collection  something gathering separated things (entities/situations) and that is not a spatial object
        supertype:  abstract__entity_without_spatial_feature  e.g., knowledge, motivation, measure; properties or qualities as distinguished from any particular embodiment of the properties/qualities in a physical medium; instances of sumo#abstract can be said to exist in the same sense as mathematical objects such as sets and relations, but they cannot exist at a particular place or time without some physical encoding or embodiment
  supertype:  set_or_class  the "set_or_class" of "sets" and "classes", i.e. any "instance" of "abstract" that has "elements" or "instances"
     supertype:  set_or_class  like sumo#set_or_class but including rdfs#class too

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