Oh cool, thanks! > - Any subset which does not contain infinity We get those from the original (discrete) topology, I assume? > - Any subset containing infin

Oh cool, thanks! > - Any subset which does not contain infinity We get those from the original (discrete) topology, I assume? > - Any subset containing infinity whose complement is finite. Ohh, is this construction related to the cofinite topology, then? I always wondered what that was useful for. (I never quite made it all the way through Munkres.) Also, I start to see why Wikipedia characterizes this as `{0} u {1/n | n in N}`. Any ball containing 0 will miss only finitely many points. > So, in order for an endomap to be continuous, [...] It took me a bit to work through this from first principles, but I see! Thanks for lighting the path.