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

Study Theorem 1 on pages SF-2 and SF-3 on the associative laws: (A \cap B) \cap  C = A \cap  (B \cap  C) = A \cap  B \cap  C. Note that we can write the rightmost expression, which has no parenthesis, because \cap  is associative. Replacing \cap  by the intersection operations, gives the associative law for intersection. Prove the associative laws.
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