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DictionaryproperStrictly smaller subset
adjective

proper

Contained within a set but not equal to the whole set.

The smaller collection is a proper subset of the larger one.

Etymology
properLatinone's own or particular

Mathematics uses proper to make a relation strict. A proper subset is genuinely a part of the larger set, excluding the case in which the two are identical.

More examples

  • A set is not a proper subset of itself.
  • The proof uses a proper subgroup.
  • They compared proper and equal subsets.

Forms

proper

Similar words

strict
In strict subset, likewise excludes equality with the whole set.