flype

《Symplectic Geometry》 · 第 66–67 页 · Section 3.8，flype 的构造段落及完整 Figure 3.16 顶部局部替换图

A move is a small localised change to a diagram. […] The broken circle indicates the neighbourhood of activity: no changes are made to the diagram outside the broken circle, and no parts of the diagram except those indicated are contained within the broken circle. A move consists of replacing the diagram fragment in one circle by the one in its partner. […] At the top of Figure 3.16 is a simple move known as a flype. The circle marked “F” contains a fragment of the diagram and is called a tangle. In the diagram on the right, the tangle has been reflected in a horizontal axis and also in the plane of the page: this is equivalent to turning over the tangle about a horizontal axis.