Proposition: Subset of a Countable Set is Countable

Let $M$ be a countable set and let $A\subseteq M$ be its subset. Then, $A$ is countable.

Proofs: 1


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References

Bibliography

  1. Modler, F.; Kreh, M.: "Tutorium Analysis 1 und Lineare Algebra 1", Springer Spektrum, 2018, 4th Edition