How would I calculate the topology of a sphere, with a smaller sphere inside removed.
I know if I drill through to get to the hole, then we are back to being a sphere, and if I drill out to the other side (i.e. all the way through) then we get torus. We if I drilled to the hollowed out inner sphere and dug two different tunnels out, then what is the genus?
I don't really know how to draw this better but here is my attempt at drawing profil slice of it.
If you held the sphere and looked down a hole u would just see a sphere with a hole drilled all the way through, but all the holes meet though in the in the middle.