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Which of the following holds: $ \bigcup x \in x ,\quad \bigcup x = x ,\quad x\in \bigcup x $ ,when:

(a) $x$ is a set, (b) $x$ is an ordinal.

Can someone help me?

Thank you in advance!

  • 0
    I have one more question.If $x$ is an arbitrary set can hold $ x \subset \bigcup x$ ?2012-01-18

3 Answers 3