Given functions f A-B and g:C-D with ran(f)C,we can define a third function called the composite function from A to D.(We will usually call this the composition,rather than the composite function.This composition is the function g of:A-D defined by (g of)(x)=g(f(x)) Let R be a relation from A to B and S be a relation from B to C.Then we can define a relation,the composition of R and S written as SoR.The relations SoR is a relation from the set A to the set C and is defined as follows: If aA,and c A,then (a,c)SoR if and only if for some be B,we have (a,b)R and (b,c)eS. 问题7：这两个定义有什台关联？有区别吗？