A knot is created by beginning with a one-dimensional line segment, wrapping it around itself arbitrarily, and then fusing its two free ends together to form a closed loop . Simply, we can say a knot formula_3 is a "simple closed curve" or "(closed) Jordan curve" (see Curve) — that is: a "nearly" injective and continuous function formula_4, with the only "non-injectivity" being formula_5. Topologists consider knots and other entanglements such as links and braids to be equivalent if the knot can be pushed about smoothly, without intersecting itself, to coincide with another knot.