University of California, San Diego: Edward Bender and S. Williamson's "Sets, Equivalence and Order: Sets and Functions"

Study the identities (equality of two set expressions) on pages SF-3 and SF-4 (the top of SF-3 and examples 2, 3, and 4). It follows from the definition of the empty set that A \cup  Ø = A, A \cap  Ø = Ø. Prove these identities.
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