\begin{graph}
    rankdir=LR
    node [shape=plaintext]
    $v_1$(2)
    $v_1$ -> $v_2$ [label=$\sqrt{2}+\frac{1}{x+5}$(5)]
    $v_2$ -> $v_3$ [label=$S \subseteq \{1,2,3\}^4$(4)]
    $v_3$ -> $v_1$ [label=$(f \circ g)^{-1}$(7)]
    A -> B [dir=none]
\end{graph}