The correct spelling "contractible" yields useful Google results, namely that spheres in 3 dimensions (point 4) are not contractible to a single point.
Edit: ... and maybe circles (point 2) too? Not a mathematician.
> The correct spelling "contractible" yields useful Google results, namely that spheres in 3 dimensions (point 4) are not contractible to a single point.
The claim is about the interior, not the sphere itself (which certainly is not contractible, as you say).
