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by superhuzza 1036 days ago
There is a distinction between a torus and a solid torus

A torus is like an inner tube - an inner void and a big hole in the middle.

A solid torus just has a big hole in the middle, like a donut.

https://en.wikipedia.org/wiki/Solid_torus

1 comments

You probably are aware, but just to make it clear for others: topologically a torus has one hole (genus 1). The inner void is not considered a hole. Similarly, a 2-sphere (surface of solid sphere in 3d) has 0 holes (the inner void is not considered).
to be slightly more technical what you're defining as "voids" are often considered 2-dimensional holes (as formalized by homology)