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Everything about Countable set

Mathematical set that can be enumerated

A mathematical set is countable if either it is finite or it can be put in one to one correspondence with the set of natural numbers. Equivalently, a set is countable if there exists an injective function from it into the natural numbers; this means that each element in the set may be associated to a unique natural number, or that the elements of the set can be counted one at a time, although the counting may never finish due to an infinite number of elements. Wikipedia →

🧭 Start here: a 6-step reading path

  1. Read the overview: Countable setA 5-minute orientation
  2. Skim a recent paper: Comments on “Fractal set of generalized countable partial iterated function system with generalized contractions via partial Hausdorff metric”Influential work since 2022
  3. Pick up a classic book: Mathematical structures for computer scienceThe most-reprinted book on the subject
  4. Read the landmark paper: Ultrafilters on a countable setCited 122 times
  5. Go sideways: Cantor's diagonal argumentA closely related topic
  6. Go sideways: EnumerationA closely related topic

📖 Definitions

Noun A set that is countable.

🏆 Landmark papers (most cited)

🆕 Influential since 2022

📚 Books worth reading

Ranked by number of editions on Open Library, a rough measure of how lasting a book is.

🔗 Related topics