Assertion: sphere | /r/HasProperty | open
Facets:
Source sentences:
text: A sphere is rotationally symmetric, and is open or closed depending on whether or not a hyperbolic rotation is involved.
text: While outside mathematics the terms "sphere" and "ball" are sometimes used interchangeably, in mathematics the above distinction is made between a sphere, which is a two-dimensional closed surface embedded in a three-dimensional Euclidean space, and a ball, which is a three-dimensional shape that includes the sphere and everything inside the sphere (a closed ball), or, more often, just the points inside, but not on the sphere (an open ball).