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by Ciro Santilli (@cirosantilli, 37)

Cardinality

 Home Mathematics Area of mathematics Formalization of mathematics Set (mathematics)
 1 By others on same topic  0 Discussions  Updated 2025-05-29  +Created 1970-01-01  See my version
The size of a set.
For finite sizes, the definition is simple, and the intuitive name "size" matches well.
But for infinity, things are messier, e.g. the size of the real numbers is strictly larger than the size of the integers as shown by Cantor's diagonal argument, which is kind of what justifies a fancier word "cardinality" to distinguish it from the more normal word "size".
The key idea is to compare set sizes with bijections.

 Ancestors (5)

  1. Set (mathematics)
  2. Formalization of mathematics
  3. Area of mathematics
  4. Mathematics
  5.  Home

 Incoming links (3)

  • Algebraic number field
  • Infinity
  • Order (algebra)

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 Articles by others on the same topic (1)

Cardinality by Wikipedia Bot 0  1970-01-01
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