1. The problem statement, all variables and given/known data This is a seemingly subtle point here, that would actually clear up both of the two previous posts I have made. A relation R is said to be defined on S and T if [tex] s \in S [/tex] and [tex] s \in dom(R) [/tex]. 2. Relevant equations na 3. The attempt at a solution Does this mean, that if I see a question that starts if R is defined on S ... that I can assume if I define a relation on S, call it T, that the domain of T must also be S. Or for any relation that we define on a set, it can be assumed that the domain of the relation is that set?