Boundary parallel
In mathematics, a closed n-manifold N embedded in an -manifold M is boundary parallel if there is an isotopy of N onto a boundary component of M.An example
Consider the annulus. Let π denote the projection map
If a circle S is embedded into the annulus so that π restricted to S is a bijection, then S is boundary parallel.
If, on the other hand, a circle S is embedded into the annulus so that π restricted to S is not surjective, then S is not boundary parallel.
