Here is the question I am trying to solve:
I imagine that I would begin by trying to prove that:Let R be a relation from A to B and S be a relation from B to C
Prove that: Dom($\displaystyle S \circ R$) $\displaystyle \subseteq $ Dom(R)
$\displaystyle \varphi \in$ Dom ($\displaystyle S \circ R$) $\displaystyle \Rightarrow \varphi \in$ Dom(R)
however, I have no idea how to go about doing this. no doubt this stems from my inability to define the domain of a composite function
any help would be much appreciated!