Quinzio, I believe that is true. If S^int is empty, then S = the boundary of S.
Here is the proof I came up with, can somebody verify it?Given S, we know that S^c = { y in R^n : a•y ≠ 0 } which is not empty.
Let x be in S and suppose that its interior is not empty.
Then there exists an r > 0...
Homework Statement
Here is a picture of the problem:
http://img84.imageshack.us/img84/1845/screenshot20100927at111.png
If the link does not work, the problem basically asks:
Let "a" be a non-zero vector in R^n. Let S be the set of all orthogonal vectors to "a" in R^n. I.e., a•x = 0 (where •...