If the function f {\displaystyle f} is thought of as a relation ( x , f ( x ) ) {\displaystyle (x,f(x))} on the Cartesian product E × F , {\displaystyle E\times F,} then the restriction of f {\displaystyle f} to A {\displaystyle A} can be represented by its graph G ( f | A ) = { ( x , f ( x ) ) ∈ G ( f ) : x ∈ A } = G ( f ) ∩ ( A × F ) , {\displaystyle G({f|}_{A})=\{(x,f(x))\in G(f):x\in A\}=G(f)\cap (A\times F),} where the pairs ( x , f ( x ) ) {\displaystyle (x,f(x))} represent ordered pairs in the graph G . {\displaystyle G.}