Knot (mathematical)

In knot theory, a knot is an embedding of a circle in 3-D space, considered up to deformations (isotopies). This is basically equivalent to a conventional knot with the ends of the string joined together to prevent it from becoming undone. In higher dimensions, circles are unknotted anyway, so one considers embeddings of spheres and hyperspheres, always in codimension 2.

This article is a stub. You can help Wikipedia by fixing it.