Deg tusnakt, Tasɣent d tafekka tasnakant i d-isgensisen assaɣ imisin i teqqnen yal aferdis seg tagruma yettwassmman tagruma n tbadut neɣ tagrawt n tbadut neɣ taɣult X {\displaystyle X\!} s yiwen n uferdis deg tegrawt yettusemman tazdaɣult neɣ taɣult tamudemt. Neɣ s usemres n taftart tasnakant tamaddudt: f : X → Y , x ↦ f ( x ) {\displaystyle f\colon X\rightarrow Y,x\mapsto f(x)\!} Seg usenmel-a, ttwafarasen-tt-d waṭas n tɣawsiwin tigejdanin: I yal amsedfar tagrawt tabadut tettwasemma X {\displaystyle X\!} . I yal amsedfar n tegrawt n tezdaɣult tettwasemma Y {\displaystyle Y\!} . Ulamek ɣef uferdis seg tegrawt n tagruma X {\displaystyle X\!} ad tettwaqqen anagar s uferdis amyiwen seg tegrawt n tezdaɣult Y {\displaystyle Y\!} . Aferdis seg tegrawt n tezdaɣult Y {\displaystyle Y\!} yezmer ad yettwiqqen s yiwen n uferdis neɣ ugar seg tegrawt n tegruma X {\displaystyle X\!} .Ma tella tegruma d tagrawt n wazalen i yezmer umeskil imziregad yawi x {\displaystyle x} , ihi tazdaɣult d tagrawt n wazalen unẓiren i wazalen n tesɣent f ( x ) {\displaystyle f(x)\!} . Imedyaten Irmawen Tilmas n tesɣanin Amezruy Tiwlafin == Ẓeṛ daɣen ==