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In: Advanced Math

Answer for a and be should be answered independently. Let (X,d) be a metric space, and...

Answer for a and be should be answered independently.

Let (X,d) be a metric space, and

a) let A ⊆ X. Let U be the set of isolated points of A. Prove that U is relatively open in A.

b) let U and V be subsets of X. Prove that if U is both open and closed, and V is both open and closed, then U ∩ V is also both open and closed.

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