[latex] File \;\;\; (z) \;\;\; directory \;\;\; (x,y) \\ (x1,y1,z1) \; (x2,y2,z2) \\ source \; directory \; and \; file \; (x1,y1,z1) \\ destination \; directory \; and \; file \; (x2,y2,z2) \\ A \;\; function \;\; \ f \ (x1,y1,z1) \;\; \longrightarrow \;\; (x2,y2,z2) [/latex]