Assertion: curvature's geometry | /r/HasProperty | special
Facets:
value: very
type: DEGREE
Source sentences:
text: Let $r : (a,b) \to \mathbb{R}^3$ be a smooth curve $r=r(s)$ in three-space parametrized by archlength $s$ (important detail) and of non-zero curvature (otherwise, the frame and the equations are not defined, but usually these are exceptional points or the curve has a very special geometry).