Arguably you can do that in 3D, if you accept the horned sphere as a knot. Though I suppose that does raise the question of what you are willing to call a sphere.
Regardless it's an embedding of a sphere that cannot be deformed into a unit sphere so I think the analogy holds.
Arguably you can do that in 3D, if you accept the horned sphere as a knot. Though I suppose that does raise the question of what you are willing to call a sphere.
Regardless it's an embedding of a sphere that cannot be deformed into a unit sphere so I think the analogy holds.