Graph of function

Graph of function --- граф функции.

Let [math]\displaystyle{ X }[/math] and [math]\displaystyle{ Y }[/math] be arbitrary nonempty sets and a function

[math]\displaystyle{ f: \; M \subseteq X \rightarrow Y. }[/math]

By [math]\displaystyle{ gr(f) }[/math] we denote the graph of funciton [math]\displaystyle{ f }[/math], i.e.

[math]\displaystyle{ gr(f) = \{(x, f(x)) | \; x \in M\} }[/math].