Section 32: Problem 10 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
In the Supplementary Exercises (exercise 7(c)) of Chapter 2 we have shown that
is regular. The previous exercises shows that it does not have to be normal.