Fighter Calls Out Henry Cejudo for His Comments. EssentiallySports. 2020-08-08 [2020-10-03]. (原始内容存档于2022-11-07) (美国英语). Holland, Jesse. Khabib declares
集合範疇是關係範疇的(寬)子範疇,其中集合範疇的態射 f : X ⟶ Y {\displaystyle f:X\longrightarrow Y} 對應至以 ( x , y ) ∈ F ⟺ f ( x ) = y {\displaystyle (x,y)\in F\iff f(x)=y} 定義的關係 F ⊆ X × Y {\displaystyle