'(everywhere)function 令(1)D0m广=A; 令(2if(a,b)and(a,b)∈f, then b=b 令 Relation:(a,b),(a,b)∈R, 今 function:if(a,b)and(a,b)∈f, then b=b ☆ Relation: LorCa &(everywhere)function: DomR-A❖ (everywhere)function: ❖ (1)Domf=A； ❖ (2)if (a,b) and (a,b')f, then b=b‘ ❖ Relation: (a,b),(a,b')R, ❖ function : if (a,b) and (a,b')f, then b=b‘ ❖ Relation: DomRA ❖ (everywhere)function: DomR=A