If you compactify the plane correctly, the exterior of a circle is homeomorphic to a disk. This follows from the Jordan-Schoenflies theorem. Defining what something is is the same as defining what it is not.
If you compactify the plane correctly, the exterior of a circle is homeomorphic to a disk. This follows from the Jordan-Schoenflies theorem. Defining what something is is the same as defining what it is not.