Section 26: Problem 2 Solution
Working problems is a crucial part of learning mathematics. No one can learn topology merely by poring over the definitions, theorems, and examples that are worked out in the text. One must work part of it out for oneself. To provide that opportunity is the purpose of the exercises.
James R. Munkres
(a) Any open set in a collection that covers a set covers all but finitely many points of the set. Therefore, a finite subcollection covers it all.(b) No. Let
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