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Lemma: Finite Cardinal Numbers and Set Operations
Let \(X, Y, U\) and \(W\) be finite sets. The following properties of cardinal numbers are fulfilled:
(1) From \(X=Y, U=W\) and \(X\cap U=\emptyset, Y\cap W=\emptyset\) it follows that \(X\cup U=Y\cup W=X + U=Y + W\).
(2) From \(X=Y\) and \(U=W\) it follows that \(X\times U=Y\times W=X\cdotU=Y\cdotW\).
Table of Contents
Proofs: 1
Mentioned in:
Proofs: 1 2
Propositions: 3
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References
Bibliography
 Ebbinghaus, H.D.: "Einführung in die Mengenlehre", BI Wisschenschaftsverlag, 1994, 3th Edition