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Lemma: Properties of Ordinal Numbers

If \(X\) is a set of ordinal numbers, then the "union":https://www.bookofproofs.org/branches/axiom-of-union-ernst/

\[\bigcup X:=\bigcup_{\alpha\in X} \alpha \] and the intersection of its elements \[\bigcap X:=\bigcap_{\alpha\in X} \alpha \] are also ordinal numbers.

Table of Contents

Proofs: 1

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Definitions: 1

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References

Bibliography

1. Hoffmann, Dirk W.: "Grenzen der Mathematik - Eine Reise durch die Kerngebiete der mathematischen Logik", Spektrum Akademischer Verlag, 2011