Comment by BigTTYGothGF 3 days ago > you can put a cd shaped object onYou're thinking of open sets. 2 comments BigTTYGothGF Reply BigTTYGothGF 3 days ago In particular, consider two intersecting planes. You can put all the discs you like on that surface, but it's not a manifold because on the line of intersection it's not locally R2.
BigTTYGothGF 3 days ago In particular, consider two intersecting planes. You can put all the discs you like on that surface, but it's not a manifold because on the line of intersection it's not locally R2.
In particular, consider two intersecting planes. You can put all the discs you like on that surface, but it's not a manifold because on the line of intersection it's not locally R2.