since I don't want to write down a whole page of the book, you need to have the book to answer me. I'm aware of that and I hope someone has it.
On page 8 Milnor shows that # is locally constant as a function of y.
That means, that for every regular value y, there exists a neighborhood V of y in N, so that every x in V is a regular value (did i get this right?) and # =# for every y' in V.
In the last line of the section, he shows a possible neighborhood V of y:
I see that is a neigborhood of y, but why is it still one, if you remove ?
Thanks in advance,