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Consider the class C of all intervals of the form (a, b), a, b ∈ R,...

Consider the class C of all intervals of the form (a, b), a, b ∈ R, a < b and ∅. Show that C is closed under finite intersections but not under complementations or unions. Hint: to show closure of finite intersections, it is enough to prove closure for intersections of 2 sets.

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