Symplectic Geometry
《Symplectic Geometry》 · 第 25 页 · Section 1.11，Definitions 1.11.1–1.11.2
A point \(p\) in a knot \(K\) is locally flat if there is some neighbourhood \(U\ni p\) such that the pair \((U,U\cap K)\) is homeomorphic to the unit ball, \(B_0(1)\), plus a diameter. A knot \(K\) is locally flat if each point \(p\in K\) is locally flat. […] A (tame) knot \(K\subset\mathbb R^3\) is a locally flat subset of points homeomorphic to a circle.