喺幅圖入面，如果將連接任何兩個物件之間唔同嘅路徑上面嘅態射覆蓋埋一齊，得到嘅結果都係一樣嘅話，咁呢個圖就係一幅交換圖。另外，習慣嚟講，實線係代表任意畀咗嘅態射，虛線就係由其他態射整出嚟嘅態射。
In this diagram, if the morphism on the different paths connecting any two objects is overlaid together, and the result is the same, then the diagram is an exchange diagram. In addition, it is customary to say that the solid line represents the form that is given arbitrarily, and the dotted line is the form that is formed from other forms.